Some useful links

Perhapts you are familiar with these; I had looked at these websites before but not realized their breath until today. It will be nice to never have to check out a Maritian book again.

First Link: Aristotlian Thomism
Second Link: Natural Law

Via Resolutionis

In the prooemium to his commentary on the Metaphysics of Aristotle, St. Thomas explains the necessity for a master science, wisdom, which will order all the others to the one end of human happiness.[1] This ruling science will be the most intellectual, he argues, just as in political matters the men strongest in intellect are the most fit to rule. Furthermore, that science is the most intellectual which treats of the most intelligible things (maxime intelligibilia).[2]

St. Thomas then gives three different accounts of what makes a thing to be most intelligible. First, from the point of view of order of understanding (intelligendi), since understanding causes is the source of scientific certainty, the knowledge of causes is more intellectual than knowledge of effects. The most intellectual of all sciences, therefore, and the one most worthy of the name wisdom, is the one which studies the highest causes.[3]

Second, because the intellect differs from sensation by grasping universal objects rather than particular, the most intellectual objects are the most universal. Therefore, wisdom will treat of the most universal principles, such as being, one and many, act and potency.[4]

Third, from the point of view of the kind of knowledge had by the intellect, which is an immaterial power, those things are most intelligible - most suited to be known by an intellect - which are most separate from matter. God and separate substances are free, not only from signate matter like the objects of physics,[5] but from all sensible matter. Furthermore, they are not only free from sensible matter in thought, like the objects of mathematics,[6] but in reality (secundum esse). Therefore, the science that studies God and separate substances will be the most intellectual and will be regulative of the other sciences.[7]

But these are not three different sciences, each competing for the title of wisdom; rather, they are three different considerations of the same science, from which considerations it receives three different names. Because it studies God and separate substance, it is called theology;[8] because it studies the common notions of being and its consequents, it is called metaphysics;[9] because it studies the first causes of things, it is called first philosophy.[10]

Of interest to this paper is the account for the second name given to the science of wisdom, metaphysics. This name is appropriate, says St. Thomas, because the universal objects studied by wisdom are found after the study of physics by way of resolution (via resolutionis) to what is more common.[11] At first glance, specifying the path toward objects beyond physics as resolutory may seem like an interesting detail, but unrelated to the main argument that metaphysics is wisdom; however, a precise understanding of the sense of resolution employed here,[12] filled out by comparison to other texts of St. Thomas, reveals that his mention of resolution actually reinforces his notion of the sapiential character of metaphysics.


We begin by taking a closer look at the description of resolution given in the text of the prooemium itself. First, as we have seen, St. Thomas gives three accounts for what makes an object intelligible, corresponding to three names given to the science of wisdom. Only the second name is attributed to the science on account of its proper subject. In this text, wisdom is called both “theology” and “first philosophy” in virtue of its treatment of God and separate substances, which are both first among causes and the most immaterial of beings. But these are treated in the science only insofar as they are the causes of its subject. On the other hand, it is called “metaphysics” in virtue of the most universal principles, being and what follows being. These most universal principles are the proper subject of wisdom.[13]

The second point we can see in the text of the prooemium is that resolution leads us to more universal knowledge. The subject of metaphysics, being and its consequents, “are discovered by way of resolution, as the more common after the less common.”[14] Ens commune, which has the broadest reach of predicability, is the terminus of the via resolutionis.

Resolution for the Sake of Judgment

There is a rich discussion of resolution and its function within science in St. Thomas’ Commentary on the De Trinitate of Boethius. In q. 6, a. 1, St. Thomas sets out to defend Boethius' claim that natural science proceeds rationabiliter, mathematics proceeds disciplinabiliter, and metaphysics proceeds intellectualiter. He divides this article into three parts corresponding to each element of Boethius' assertion.

St. Thomas first defends calling the mode of natural science rationabiliter. In doing so, he lists three ways in which a scientific process can be called "reasonable": from the principles of the process, from the end of the process, or from the power of the soul which undergoes the process.

First, a mental process can be called reasonable if it proceeds from principles taken from works of reason, or logical intentions, such as genus, species, and opposite. This sense of "reasonable" applies when the principles of an argument are "beings of reason" as opposed to "real beings".[15] Second, a mental process can be called reasonable if it has not yet terminated in its ultimate goal of understanding principles. He contrasts the process of reasoning which is still moving, still seeking out middle terms, to the demonstration which has reached first principles. Only the former is called "reasonable", while the latter is more properly called "demonstrative".[16] Third, a mental process can be called reasonable insofar as it follows a mode proper to human way of knowing. This happens by following a course of reasoning from what is more known to us to what is more known by nature, as well as by moving discursively from one thing to another. It is this last sense of reasonable that St. Thomas says is proper to natural science, since both aspects of human reasoning are most properly displayed in physics.

The second reason St. Thomas gives for calling a mental process reasonable is the first mention in this text of resolution. St. Thomas says that we judge by resolving into first principles.[17] He is pointing out that the conclusions of reason are judged to be true only by seeing in them the power of the first principles, which are known immediately to be true.[18] This resolution is what gives solidity to the final conclusion, rendering the knowledge scientifically certain rather than probable.

This account of reasonable which distinguishes a process from demonstrative is rejected as an interpretation of Boethius’ description of physics as rationabiliter. Since any science requires the completion of this process of reason such that its conclusions are firmly tied down to self-evident truths, this account cannot be proper to natural science. Neither, then, can it be identical to the via resolutionis which leads to metaphysics. For St. Thomas, physics and mathematics possess a scientific independence, since they each can resolve their conclusions to their proper first principles. If the via resolutionis were identical to the sense of resolution which links conclusions to principles, only a metaphysical consideration would render mathematics and physics demonstratively certain. Nevertheless, we will see later that resolution leading to judgment bears a certain similarity to the resolution leading to metaphysics. For now, it is enough to note that St. Thomas assigns the process of resolving to discursive reason, while the principles to which reason resolves are understood by the intellect.[19]

Metaphysics’ Relation to Other Sciences

After arguing for mathematics’ status as disciplinabiliter, St. Thomas turns to defending Boethius' claim that divine science proceeds intellectualiter. He first describes the difference between reason and intellect. Reason stands to intellect as multitude to unity. He posits this analogy as the basis for two others given by Boethius: reason is to intellect as time is to eternity and as a circle is to its center.[20] To explain this relationship further, he says that it is proper to reason to be diffused over many things, and from the many things to collect one simple apprehension. Intellect, however, considers first one simple truth in which it grasps a multitude of things.[21]

St. Thomas then draws the conclusion that rational activity finds its completion in intellectual activity according to the path of resolution (secundum viam resolutionis). This is due to what he said above, namely that reason draws one simple truth, the apprehension of which is the proper domain of the intellect, from many. On the other hand, intellectual understanding is the starting point of reasoning according to the path of composition or discovery (secundum viam compositionis vel inventionis). Intellect, then, stands to reason as principle and terminus. Therefore, drawing out the analogy, St. Thomas will argue that whichever science stands to the other sciences as principle by way of composition and terminus by way of resolution most deserves to be described as "intellectual."[22]

He then makes another distinction in the way reason proceeds. All rational activity is discursive, but this movement can be from one thing to another, according to extrinsic cause and effect, or from one intelligibility to another, according to intrinsic cause and effect.[23] There are, therefore, two modes of composition, and two mode of resolution.[24] Resolution secundum rem terminates in the separate substances,[25] while resolution secundum rationem terminates in being and its proper passions considered universally.[26] Since wisdom considers those things that are at the ultimate end of rational resolution, it stands to the other sciences as intellectual to rational.

According to the thought of St. Thomas, then, not only is wisdom the most intellectual of sciences,[27] but it relates to the other sciences as intellectual to rational. It is true that St. Thomas is careful to avoid identifying metaphysics with the act of the intellect: he does not claim that intellect operates exclusively in the domain of metaphysics, nor that metaphysics operates exclusively intellectually.[28] Nevertheless, St. Thomas has defended Boethius’ description of metaphysics as proceeding intellectualiter, and has argued for this appellation on the basis of its relation to other sciences. This analogy will enter into our solution of a difficulty, which will ultimately shed light on the via resolutionis and the ordering function of wisdom.

A Difficulty

The difficulty concerns what appears to be at the heart of the meaning of resolution: a movement toward what is more simple. We have seen that in q. 6, a. 1 of his commentary on Boethius’ De Trinitate, St. Thomas explicitly connects resolution with proceeding toward what is more simple, both in the case of resolution secundum rem and secundum rationem.[29] In both cases, in fact, simplicity of the terminus is the reason why St. Thomas calls the movement resolution. This argument is evidence that St. Thomas sees resolution generally as a movement to the more simple.[30] The simplicity of universals provides a terminus for a particular kind of resolution.

But in what way are universals simple? In other texts, St. Thomas speaks of more universal concepts as complex and confused compared to more particular concepts. For instance, in q.1, a.3 of the same commentary on Boethius’ De Trinitate, St. Thomas, in discussing the order in which things are abstracted by the intellect, speaks of universal concepts as composed wholes which are known before their simpler parts.[31]

Again, in the first lecture of his commentary on Aristotle’s Physics, St. Thomas not only describes the movement from universal to particular as a movement from confused wholes to simpler distinct elements, but even calls such a movement resolution. Aristotle had concluded that for a natural scientist “it is necessary to go from the universal to the particulars.”[32] St. Thomas explains the argument this way: it is natural for us to proceed from knowing those things that are more known to us, to those things that are more knowable in themselves. But since what is more known to us is more confused, and knowledge of universals is more confused than knowledge of particulars, therefore Aristotle’s conclusion follows and we must proceed from confused universals to distinct particulars.[33]

St. Thomas then argues for the second claim, namely that what is more known to us is more confused. What he means by confused knowledge is indistinct knowledge, which has some admixture of potency, as opposed to distinct knowledge which is the intellect fully in act. But our intellects proceed from potency to act; therefore, we must pass through confused and indistinct knowledge before arriving at distinct knowledge. He describes this process as a resolution (resolutionem), noting that by it we come to a perfectly actualized science when we have distinct knowledge of principles and elements.[34]

He then defends his previous assertion that universals are one kind of confused object of knowledge, since what is known through a universal is known indistinctly. The thing known universally is known in its species only potentially; for example, if someone knows what an animal is, he does not by this fact actually know what it is to be rational, even if some animals are rational. The rational sort of animal is contained under the notion of animal only potentially: if rational were known actually by knowing animal, there couldn’t be any non-rational animals; and if rational were in no way known by knowing animal, there couldn’t be any rational animals. Therefore, in this text, St. Thomas is clear that we must proceed from confused universal knowledge to distinct particular knowledge by way of resolution.[35]

In his commentary on Aristotle’s Metaphysics, he references the same text from the Physics, again associating it with “resolution.” Here, he is explaining in what sense it is difficult to know the truth. The difficulty stems from our inability to grasp a whole and its parts at the same time.[36] He lays out two processes by which the mind progresses. Starting with some truth that is known to all, one searching for truth may proceed by way of resolution (per modum resolutionis), which he describes as a movement from composite to simple, and from whole to part. He then connects this process of resolution to that mentioned in the text from the Physics which we have already discussed. The end and perfection of this path to the truth is reached with the distinct knowledge of the parts of what was first known confusedly. The way of composition (via compositionis), by contrast, proceeds from the simple to the composed, and is perfected when the whole is grasped.[37]

Universals as Causes

We can perhaps discern in what way St. Thomas views universals as more simple than the particulars contained under them from his response to q. 7, a. 8 of the De Potentia.[38] St. Thomas is asking whether there are any relations between creatures and God. It seems that the main objection to affirming such relations is that they would do violence to God’s simplicity. On the contrary, St. Thomas declares that the simpler something is, the more relations it will have due to its less limited power.[39] He resolves the same problem in a similar way in chapter 13 of the second book of his Summa Contra Gentiles.[40] Although both this text and the previous one are discussing God as the cause who extends His power over all, it seems to be a general principle that more common causality is a sign of simplicity. St. Thomas applies the principle to mathematics, remarking that a point, the simplest mathematical, is a principle of more things than a line.[41] In fact, it is a commonly repeated principle of St. Thomas, that causal extension toward many things is a sign of simplicity.[42]

At this point we should recall the relation of wisdom to other sciences as intellect to reason. Reason draws one from many in the process of resolution according to intrinsic and extrinsic causes.[43] Ens commune, therefore, which is the completion of resolution secundum rationem, is not considered as a confused whole which stands to its distinct parts as complex to simple, as it is in the passages where St. Thomas speaks of a resolution from the universal to particular. It is, rather, considered as an intrinsic formal principle, relating as a principle to more things than less universal principles. It is in this way that universals are simple.[44]

Nevertheless, although each can be said to be simple and extend their causality over all things, we must insist that St. Thomas emphatically denies the position that ens commune is God.[45] There is a great gap between resolution secundum rationem and secundum rem.[46] For, as we have seen, the terminus of resolution secundum rationem forms the proper subject of metaphysics; God and separate substances, however are studied as the causes of ens commune at the culmination of wisdom.


St. Thomas has drawn an analogy between the parts of an individual science and the sciences themselves. The role that the intellectual understanding of principles and the terminus of resolution play in any particular science, metaphysics plays with respect to the lower sciences. Furthermore, the via resolutionis is a movement according to intrinsic causes, which movement finally achieves the most universal, simple, and expansive formal causes: being, one and many, act and potency, and the like. It is not out of place, therefore, to speak of the role of resolution as it pertains to judgment in the context of this analogy. Just as the ultimate grounding of any particular science is a product of resolution to first principles, so the whole course of human knowledge is completed and grounded in the science of metaphysics. Without doing violence to the scientific certainty obtainable in mathematics and physics prior to a metaphysical grasp of being, St. Thomas is able to say that without knowledge of these ultimate formal principles, the knowledge of any particular kind of thing is not complete.[47] The resolution to self-evident principles in any particular field of study provides the basis for judging and ordering the conclusions of that science; similarly, the via resolutionis which obtains the most universal principles allows metaphysics to take its privileged place among the sciences, ordering and judging its inferiors as wisdom.


Aertsen, Jan A. "Method and Metaphysics: The via resolutionis in Thomas Aquinas." Modern Schoolmen 63, no. 4 (1989): 405-418.

Aquinas, St. Thomas. Expositio Super Librum Boethii De Trinitate. 2nd ed. Edited by B. Decker. Leiden: E.J. Brill, 1965.

—. In Duodecim Libros Metaphysicorum Aristotelis Expositio. Edited by M. R. Cathala and R. M. Spiazzi. Turin-Rome: Marietti, 1950.

—. In octo libros Physicorum Aristotelis expositio. Edited by M. Maggiòlo. Taurin: Marietti, 1954.

—. Liber de veritate catholicae Fidei contra errores infidelium seu Summa contra Gentiles. Edited by C. Pera, P. Caramello P. Marc. Taurini-Romae: Marietti, 1961.

—. Opera omnia iussu impensaque Leonis XIII P. M. edita, t. 4-5: Pars prima Summae theologiae. Romae: Ex Typographia Polyglotta S. C. de Propaganda Fide, 1888-89.

—. Opera omnia iussu Leonis XIII P. M. edita, t. 1*/2: Expositio libri Posteriorum. 2nd ed. Roma-Paris: Commissio Leonina-J. Vrin, 1989.

—. Quaestiones disputatae, t. 2: Quaestiones disputatae de potentia. 10th ed. Edited by P.M. Pession. Taurini-Romae: Marietti, 1965.

—. Scriptum super libros Sententiarum magistri Petri Lombardi episcopi Parisiensis, t. 2. Edited by P. Mandonnet. Parisiis: P. Lethielleux, 1929.

Aristotle. Physics. Translated by Glen Coughlin. South Bend, Indiana: St. Augustine's Press, 2005.

Boethius. The Consolation of Philosophy. Translated by Richard Green. New York: Macmillan, 1962.

Oeing-Hanhoff, L. "Die Methoden der Metaphysik im Mittelalter." In Die Metaphysik im Mittelalter, Ihr Ursprung und ihre Bedeutung, edited by P. Wilpert, 71-91. Berlin, 1963.

Régis, L. M. "Analyse et synthèse dans l'œuvre de Saint Thomas." In Studia Mediaevalia in honorem admodum Reverendi Patris Raymundi Josephi Martin, 303-330. Brugge, 1940.

Sweeney, Eileen C. "Three Notions of Resolutio and the Structure of Reasoning in Aquinas." The Thomist 58 (1994): 197-243.

Wippel, John F. "Aquinas and Participation." In Studies in Medieval Philosophy, edited by John F. Wippel, 117-158. Washington, DC: Catholic University of America Press, 1987.

—. "'First Philosophy' According to Thomas Aquinas." In Metaphysical Themes in Thomas Aquinas, by John F. Wippel, 55-67. Washington, DC: Catholic University of America Press, 1984.

[1] In Duodecim Libros Metaphysicorum Aristotelis Expositio, ed. M. R. Cathala and R. M. Spiazzi (Turin-Rome: Marietti, 1950), proem., 1: “Omnes autem scientiae et artes ordinantur in unum, scilicet ad hominis perfectionem, quae est eius beatitudo. Unde necesse est, quod una earum sit aliarum omnium rectrix, quae nomen sapientiae recte vindicat. Nam sapientis est alios ordinare.”

[2] Ibid.: “Sicut enim, ut in libro praedicto Philosophus dicit, homines intellectu vigentes, naturaliter aliorum rectores et domini sunt: . . . ita scientia debet esse naturaliter aliarum regulatrix, quae maxime intellectualis est. Haec autem est, quae circa maxime intelligibilia versatur.”

[3] Ibid.: “Unde, cum certitudinem scientiae per intellectum acquiratur ex causis, causarum cognitio maxime intellectualis esse videtur. Unde et illa scientia, quae primas causas considerat, videtur esse maxime aliarum regulatrix.”

[4] Ibid.: “Unde et illa scientia maxime est intellectualis, quae circa principia maxime universalia versatur. Quae quidem sunt ens, et ea quae consequuntur ens, ut unum et multa, potentia et actus.”

[5] See Aquinas’ Expositio Super Librum Boethii De Trinitate, 2nd ed., ed. B. Decker (Leiden: E.J. Brill, 1965), q. 5, a. 3.

[6] Ibid.

[7] In Meta., proem., 1: “Nam cum unaquaeque res ex hoc ipso vim intellectivam habeat, quod est a materia immunis, oportet illa esse maxime intelligibilia, quae qunt [sic] maxime a materia separata.”

[8] Ibid., 2: “Dicitur enim scientia divina sive theologia, inquantum praedictas substantias considerat.”

[9] Ibid.: “Metaphysica, inquantum considerat ens et ea quae consequuntur ipsum.”

[10] Ibid.: “Dicitur autem prima philosophia, inquantum primas rerum causas considerat.” But St. Thomas gives a different account of the name “first philosophy” in q.5, a.1 of his Commentary on the De Trinitate of Boethius. For a discussion of these different accounts, see John F. Wippel, "’First Philosophy’ According to Thomas Aquinas," in Metaphysical Themes in Thomas Aquinas, by John F. Wippel, (Washington, DC: Catholic University of America Press, 1984), 55-67.

[11] Ibid.: “Haec enim transphysica inveniuntur in via resolutionis, sicut magis communia post minus communia.”

[12] There have been several attempts to collect and categorize the various uses of resolutio in St. Thomas’ works: L. M. Régis, "Analyse et synthèse dans l'œuvre de Saint Thomas," in Studia Mediaevalia in honorem admodum Reverendi Patris Raymundi Josephi Martin (Brugge, 1940), 303-330; Jan A. Aertsen, "Method and Metaphysics: The via resolutionis in Thomas Aquinas," Modern Schoolmen 63, no. 4 (1989): 405-418; Sweeney, Eileen C. "Three Notions of Resolutio and the Structure of Reasoning in Aquinas," The Thomist 58 (1994): 197-243. Régis, after examining the senses of resolution (or analysis) and composition (or synthesis) in various writers prior to St. Thomas, divides his discussion of St. Thomas’ use of resolution and composition according to the three acts of reason (simple apprehension, judgment, and reasoning). He also has a distinct section on their role in practical knowledge. Aertsen, unlike Régis, is not so much trying to make a complete treatment of St. Thomas’ use of resolution as argue against L. Oeing-Hanhoff, "Die Methoden der Metaphysik im Mittelalter," In Die Metaphysik im Mittelalter, Ihr Ursprung und ihre Bedeutung, edited by P. Wilpert (Berlin, 1963), 71-91. To that end, he distinguishes resolution secundum rem and secundum rationem. Sweeney attempts to trace three different senses of resolution in St. Thomas’ works to three different sources in ancient writers. She also argues that each sense is particularly associated with a different science.

[13] In Meta., proem., p.2: “Ex quo apparet, quod quamvis ista scientia praedicta tria consideret, non tamen considerat quodlibet eorum ut subiectum, sed ipsum solum ens commune. Hoc enim est subiectum in scientia, cuius causas et passiones quaerimus, non autem ipsae causae alicuius generis quaesiti. Nam cognitio causarum alicuius generis, est finis ad quem consideratio scientiae pertingit.” See Sweeney, p.239, where she associates the sense of resolution drawn from Neoplatonic thinkers to the light under which metaphysics studies its subject.

[14] In Meta., proem., p.2: “Haec enim transphysica inveniuntur in via resolutionis, sicut magis communia post minus communia.” Translation mine.

[15] Ex. De Trin., p. 205, 6-17.

[16] Ibid., p. 205, 18–p. 206, 6.

[17] Ibid., p.205, 19-22: “Ultimus enim terminus, ad quem rationis inquisitio perducere debet, est intellectus principiorum, in quae resolvendo iudicamus; quod quidem quando fit non dicitur processus vel probatio rationabilis, sed demonstrative.”

[18] See, for instance: In II Sent., d.9, q.1, a.8, ad 1; De Verit., q.12, a.1, co.

[19] “Ultimus enim terminus, ad quem rationis inquisition perducere debet, est intellectus principiorum, in quae resolvendo iudicamus . . .” Ex. De Trin., p.205, 19-20 (emphasis mine).

[20] “Therefore, the changing course of Fate is to the simple stability of Providence as reasoning is to the intellect, as that which is generated is to that which is, as time is to eternity, as a circle to its center.” The Consolation of Philosophy, trans. Richard Green (New York: Macmillan), Bk. IV, prose 6, p.92.

[21] Ex. De Trin., p.210, 29–p.211, 14.

[22] Ibid., p.211, 15-20.

[23] Ibid., p.212, 3-5 and 10-11: “Ratio enim, ut prius dictum est, procedit quandoque de uno in alius secundum rem, ut quando est demonstratio per causas vel effectus extrinsecos…quandoque vero procedit de uno in aliud secundum rationem, ut quando est processus secundum causas intrinsecas.”

[24] For discussion on these various modes of discursive reasoning, especially as they provide two different accounts of the name “first philosophy”, as well an account for the name of “metaphysics”, see the article by John F. Wippel cited in note 8.

[25] Ex. De Trin., p.212, 8-10: “Ultimus ergo terminus resolutionis in hac via est, cum pervenitur ad causas supremas maxime simplices, quae sunt substantiae separatae.”

[26] Ibid., p.212, 15-16: “Et ideo terminus resolutionis in hac via ultimus est consideratio entis et eorum quae sunt entis in quantum huiusmodi.”

[27] See note 2 above.

[28] Wisdom is a science, and like every human science, moves discursively through reason. See Ex. De Trin., p.207, 18-22.

[29] Ex. De Trin., p.212 6-7 and 13-14: “. . . resolvendo, cum proceditur ab effectibus simpliciores ad causas, eo quod causae sunt effectibus simpliciores . . . resolvendo autem quando e converso, eo quod universalius est simplicius.”

[30] See Edmund Dolan quoted by Sweeney in the work cited in note 10 above, p.203. See also Sweeney, p.217, where she attributes a movement toward simplicity to the first two senses of resolution she has discerned in St. Thomas’ writings: "It is in one sense like the first type of resolution in that it moves from complex to simple; however, the metaphysical character of that simplicity is different in each case; one is the simplicity of parts, the other the simplicity of seamless unities."

[31] Ex. De Trin., p.72, 11-14: “Haec autem sunt quae plura comprehendunt vel per modum totius universalis vel per modum totius integralis, et ideo magis universalia sunt primo nota intellectui et composita componentibus, ut diffinitum partibus diffinitionis.”

[32] Physics, trans. Glen Coughlin (South Bend, Indiana: St. Augustine's Press, 2005), Bk. I, Ch. 1 (184a 24).

[33] In octo libros Physicorum Aristotelis expositio, ed. M. Maggiòlo (Taurin: Marietti, 1954), Bk. I, lect. 1, n.6: “Innatum est nobis ut procedamus cognoscendo ab iis quae sunt nobis magis nota, in ea quae sunt magis nota naturae; sed ea quae sunt nobis magis nota, sunt confusa, qualia sunt universalia; ergo oportet nos ab universalibus ad singularia procedere.”

[34] Ibid., n.7: “Ad intellectum autem secundae propositionis, sciendum est quod confusa hic dicuntur quae continent in se aliqua in potentia et indistincte. Et quia cognoscere aliquid indistincte, medium est inter puram potentiam et actum perfectum, ideo, dum intellectus noster procedit de potentia in actum, primo occurrit sibi confusum quam distinctum; sed tunc est scientia completa in actu, quando pervenitur per resolutionem ad distinctam cognitionem principiorum et elementorum. Et haec est ratio quare confusa sunt primo nobis nota quam distincta.”

[35] Ibid.: “Quod autem universalia sint confusa manifestum est, quia universalia continent in se suas species in potentia, et qui scit aliquid in universali scit illud indistincte; tunc autem distinguitur eius cognitio, quando unumquodque eorum quae continentur potentia in universali, actu cognoscitur: qui enim scit animal, non scit rationale nisi in potentia. Prius autem est scire aliquid in potentia quam in actu: secundum igitur hunc ordinem addiscendi quo procedimus de potentia in actum, prius quoad nos est scire animal quam hominem.”

[36] In Meta. II, lect.1, n.6.: “. . . hoc ostendit difficultatem quae est in consideratione veritatis, quia non possumus habere circa veritatem totum et partem.”

[37] Ibid.: “Est autem duplex via procedendi ad cognitionem veritatis. Una quidem per modum resolutionis, secundum quam procedimus a compositis ad simplicia, et a toto ad partem, sicut dicitur in primo physicorum, quod confusa sunt prius nobis nota. Et in hac via perficitur cognitio veritatis, quando pervenitur ad singulas partes distincte cognoscendas. Alia est via compositionis, per quam procedimus a simplicibus ad composita, qua perficitur cognitio veritatis cum pervenitur ad totum. Sic igitur hoc ipsum, quod homo non potest in rebus perfecte totum et partem cognoscere, ostendit difficultatem considerandae veritatis secundum utramque viam.”

[38] Quaestiones disputatae, t. 2: Quaestiones disputatae de potentia, 10th ed., ed. P.M. Pession (Taurini-Romae: Marietti, 1965).

[39] Ibid.: “Ex hoc autem apparet quod non est contra rationem simplicitatis alicuius multitudo relationum quae est inter ipsum et alia; immo quanto simplicius est tanto concomitantur ipsum plures relationes. Quanto enim aliquid est simplicius, tanto virtus (eius) est minus limitata, unde ad plura se extendit sua causalitas.”

[40] Liber de veritate catholicae Fidei contra errores infidelium seu Summa contra Gentiles, ed. C. Pera, P. Caramello, and P. Marc (Taurini-Romae: Marietti, 1961).

[41] Ibid., Bk. II, ch.13, n.5: “Et quanto aliquid est magis simplex, tanto est maioris virtutis et plurium principium, ac per hoc multiplicius relatum intelligitur: sicut punctum plurium est principium quam linea, et linea quam superficies.”

[42] See, for instance, De veritate, q. 8, a. 14, ad s. c. 6; De veritate, q. 5, a. 2, ad 2.

[43] See note 22 above.

[44] St. Thomas argues elsewhere that universals may be considered as parts of an intelligible structure: “Ad secundum dicendum quod universale magis commune comparatur ad minus commune ut totum et ut pars. . . . Ut pars autem, secundum quod minus commune continet in sui ratione non solum magis commune, sed etiam alia; ut homo non solum animal, sed etiam rationale.” Opera omnia iussu impensaque Leonis XIII P. M. edita, t. 4-5: Pars prima Summae theologiae (Romae: Ex Typographia Polyglotta S. C. de Propaganda Fide, 1888-89), q. 85, a. 3, ad 2, p. 337. Since parts are simpler than the wholes composed of them, this seems to another way in which universals are simple. However, the terminus of the via resolutionis is the most universal concept, being in general. Since being is not a genus, and does not receive a difference from outside itself, it cannot be said that the less universal contains more than being. Therefore, I have chosen to focus on the universal as simple in virtue of its broader extent of formal causality.

[45] See John F. Wippel, "Aquinas and Participation," in Studies in Medieval Philosophy, ed. John F. Wippel (Washington, DC: Catholic University of America Press, 1987), 117-158.

[46] Aertsen, arguing against Oeing-Hanhoff, insists that St. Thomas does not mean to reduce resolution secundum rationem to logic, or the analysis of concepts; rather, the distinction between resolving secundum rationem or secundum rem is the different ontological “direction” of each movement (Aertsen, p.414). Sweeney disagrees, claiming that resolution secundum rationem and secundum rem are both to be found in two different senses of resolution she has perceived which move in different directions (Sweeney, p.228). In any event, it is agreed that, for St. Thomas, there is a distinction between resolution according to intrinsic and extrinsic causes and the ens commune is not God.

[47] In Meta., proem., 1: ”Huiusmodi autem non debent omnino indeterminata remanere, cum sine his completa cognition de his, quae sunt propria alicui generi vel specie, haberi non possit.”

Here is my term paper on Edmund Husserl's notion of idealization in "The Crisis of the European Sciences."

Idealization is a key theme in Edmund Husserl’s unfinished, posthumous work The Crisis of European Sciences and Transcendental Phenomenology. I will investigate its function in the argument of Crisis and argue for its importance generally in understanding science. For Husserl, idealization is the process by which men achieve concepts of exact essences. The clarification of this activity is required to carry out what Husserl terms the epoché of the objective sciences, his first step in the recovery of science in its original philosophical meaning as properly inclusive “of all that is.”[1] I shall examine (I) the context, (II) the account, and (III) the function of idealization in Crisis; finally, from a comparison to the Thomistic account of idealization (IV), I will argue that Husserl notably supplements an understanding of how to avoid errors when considering man’s scientific involvement in things, chiefly in regard to modern physics.


The intention of Crisis is to manifest the need for and way to phenomenology “by way of a teleological-historical reflection upon the origins of our critical scientific and philosophical situation.”[2] I will consider these last two (crisis and origin), and, in addition, life-work or vocation.[3]

The crisis is the inability of the modern sciences—the objective sciences of physics or the modern humanities—to ask (and, a fortiori, answer) “questions of the meaning or meaninglessness of the whole of this human existence.”[4] They study the ‘objective world,’ an account of things sought in separation from the activity (and hence subjectivity) of reason. Therefore, an evaluation of idealization is required, for, “Ideal essences strive to exclude any reference to an agent or observer,”[5] and, insofar as questions concerning meaning (and their answers) bespeak consideration of the rational agent, an investigation restricted to ideal essences will fail in regard to both. This objectification as a crisis separates “reason and that-which-is . . . where reason, as knowing, determines what is.”[6] To resolve this crisis, its origin must be uncovered.

‘Origin,’ as Husserl uses it here, is considered in The Origin of Geometry.[7] The origin of a science is its “meaning-origin,”[8] its source in the order of being able to ground an articulated human theoretical work or praxis. Hence, the origin is not temporal as such, about “the first geometers who actually uttered pure geometrical propositions,” but is still used in time as that from which truth is achieved in the habitual perfection of science. Now, any such origin, since it must be articulated in time, bears two marks. First, tradition hands the origin, and progress made in the science, first in speech, then writing,[9] to later scientists. This becomes a ready-made sum total, a “pregiven.”[10] Second, a pregiven tradition entails the mark of reactivatability:

…the writing-down effects a transformation of the original mode of being of the meaning-structure, [e.g.,] within the geometrical sphere of self-evidence . . . . It becomes sedimented, so to speak. But the reader can make it self-evident again, can reactivate the self-evidence.[11]

Later scientists can arrive at the same knowledge that has been handed down through tradition by reactivating the original meaning of the sedimented science. This is possible because what science articulates is eternal: “The Pythagorean theorem, [indeed] all of geometry, exists only once . . . identically the same . . . ,” in all its traditional presentations (e.g., regardless of language). There is a danger in tradition, however, for if the origin is lost, then tradition hands down an imperfect or meaningless science.[12] This occlusion of the meaning-origin is the definition of a scientific crisis.

Finally, there is the notion of the life or work of reason: “Conscious of the world as a horizon, we live for our particular ends, whether as momentary and changing ones or as an enduring goal that guides us.”[13] The world (“. . . the totality of objects that can be known through experience . . . .”[14]) and various worlds, e.g., the natural or arithmetical,[15] are sorts of experienceable wholes that, insofar as each has a certain goal, gives a boundary to each activity of reason. As whole to part, this account of human life also characterizes the activities of the scientist. His vocation is delimited by his end of theoretical work; the end guides him actually (during the times he pursues his life-work) or endures as a habituality at other times (affecting other areas of his life). Such activities beget and add to tradition and constitute culture.[16] In this way men add to and depend upon the world. Hence, Husserl concludes that science, as a cultural influence on a man’s life, is disastrous if the reason for such an influence (its origin) is lost. Husserl’s claim is that such is the case with idealization and the objective sciences.


Husserl’s account of the process of idealization starts with the bodies given to sensible experience and ends in a theoretic achievement, an exact essence, or “identity,” or “pole,” from which empirical bodies decline.[17] Measurement is essential to this process, for it is “the praxis that links the real and the ideal,” (and in either direction).[18] Geometry will be taken as the exemplar of how men learn to consider exact essences.

The beginning of the process lies in what is given to experience: the bodies of the natural world. The sides and aspects of these empirical shapes can be considered and varied in imagination, but this only gives rise to further variations of the same: “Fantasy can transform sensible shapes only into other sensible shapes.”[19] Such transformations, however, evidence the ‘perfectibility’ of such shapes, “the capacity to make the straight straighter and the flat flatter,” which sensible or imaginable perfection (‘smoothness’) is distinct from the abstract perfection of the ideality; thus:

. . . out of the praxis of perfecting, of freely pressing toward the horizons of conceivable perfecting “again and again,” limit-shapes emerge toward which the particular series of perfectings tend, as towards invariant and never attainable poles.[20]

The key here is “out of.” The sensible experience of ‘these’ and ‘such’ variably perfect, material shapes motivates another kind of givenness. The exact essences of ‘triangle’ or ‘line,’ and other, “geometrically ‘pure’ shapes,”[21] are given only to reason. Reason depends upon the continuous and variable space of sensible experience to arrive at such exact essences, but it prescinds from the material imprecision of empirical shapes. Once the curved as ideal is known, it is recognized in the snub-nose; one sees the “ghostly presentation of the ideal essence” in all of the particulars.[22]

Husserl distinguishes between ideal (or exact) and morphological essences.[23] The latter are “vague” for they retain what is experienced indeterminately and variably in individuals albeit in a “fixed” way. The morphological essence of man cannot prescind from height or eye color, but only a particular experienced man has ‘this’ height and ‘such’ an eye color. A morphological, unlike an ideal, essence, “is not constructed or conceived as an ideal limit.”[24] This construction or “pressing toward” the one identity (limit shape) given in all declining instances allows exact essences to exclude vagueness. The difference is due to the nature of quantity. The parts of a body must be approached externally in touching, shaping, and primitive measurement. Such experiences, and imaginative variation, find in quantitative parts and wholes a consistency or style that allows for the exact identity in the variations to be seen. This ‘seeing,’ is definitional, not perceptual. Reason does not attain a ‘perfect image’ of triangle, but its account.

Husserl notes that the transition to geometric considerations is further articulated by the praxis of measurement, “surveying and measuring in general . . . .”[25] Farmers measuring fields to predict crop yield or masons their stone (with a ‘line’) to fit the parts of building together both achieve an objectivity beyond the subjective experience of perfectible shapes, for these measurements are available to all. “The art of measuring thus becomes the trail-blazer for the ultimately universal geometry in its ‘world’ of pure limit-shapes.”[26] Farmer and mason as ‘earth-measurers’ become plane and stereo-geometers.

The process of idealization, therefore, serves an activity of human reason with a delimited end. The practical art of measurement and the empirical and technological abilities that arise from such arts are carried over to an ideal realm, “In place of real praxis . . . we now have an ideal praxis of ‘pure thinking’ . . . .”[27] Idealization is required to provide the way to this activity.


The main function of idealization in the argument of Crisis is threefold: it first serves as the occluded element in the meaning-origin of modern science. In clarifying this, the relationship between the method of reason in mathematical physics and the concrete setting of such work, the “life-world,”[28] is also revealed. Husserl then uses this as the first step into phenomenology.

Towards the first, idealization is used to encapsulate the direction of the argument of Part II (§8), in its use towards the different ends of the ancient and modern ideas of mathematics. The ancient conception “knows only finite tasks, a finitely closed a priori,”[29] that is, an idealization to an immediate consideration of quantity alone (continuous or discrete). The modern age recasts this end, developing “a formal mathematics,” (Descartes’ analytic geometry) which approaches the quantitative realm as an infinite ideal system, for its logistic is a set of second intentions combinable and recombinable, according to rule, ad infinitum. This introduces the tempting “idea that the infinite totality of what is in general is intrinsically a rational all-encompassing unity that can be mastered, without anything left over, by a corresponding universal science.”[30] Koyré brings out the difference in these two approaches in this way:

The disappearance—or destruction—of the [ancient conception of] cosmos means that the world of science, the real world, is no more seen, or conceived, as a finite and hierarchically ordered, therefore qualitatively and ontologically differentiated, whole, but as an open, indefinite, and even infinite universe, united not by its immanent structure but only by the identity of its fundamental contents and laws . . . .[31]

When extended to natural science, this method redefines “philosophy in general” as conceived by the ancients.[32] The key to finding the origin of this transformation is Galilean science.[33] Two traditions are pregiven a Galilean that guide his interpretation of nature. The first is an advanced geometric tradition (inclusive of calculus); the second is the practical arts of measurement and mechanics.[34] He assumes the origins of these traditions, and seeks to apply them to the study of nature, his particular “life-work.”[35]

The first pregiven, however, deals only in exact essences; it cannot treat the concrete world of “empirical shapes,” for morphological essences cannot be treated quantitatively.[36] Yet, the experienced world exhibits a “universal causal style.”[37] Since the second pregiven shows that the universal style of idealized empirical shapes can be reintegrated into the empirical world (the classical intermediate sciences: astronomy or, as Husserl cites, Pythagorean tonality),[38] this leads the Galilean to ask, “Must not something similar be possible for the concrete world as such?”[39] This is the problem of the indirect mathematization of the sense-plenum. This sought extension differs from the classical intermediate sciences for the sense-plenum “as such” is to be quantified; mathematics will not be the formal aspect in a demonstration leading to science of sensible quantity; rather, the sense-plenum will be considered formally as quantity.

Galilean science approaches the solution to this problem by noting that the universal styles of “the specifically sensible qualities . . . are closely related in a quite peculiar and regulated way with the shapes that belong essentially to them.”[40] This regularity, however, is measurable. Therefore, by extension, exact essences can be assigned to the sense-plenum in proportion to its measurable dependence upon quantity. This “mathematical index” takes heaviness, time, warmth, or color and idealizes them to numbers, lines, “warmth-vibrations” or electromagnetic frequencies.[41]

This new mathematization, Husserl concludes, gives a meaning-origin to natural science that is both a discovery and a concealment.[42] One the one hand, a new rational science of nature is possible; on the other hand, a mathematical nature and its systematic laws of a priori causality are substituted for ‘nature’ in the old (Aristotelian) sense. This has been termed the hypostatization of geometry.[43] This concealment only becomes a problem, however, when its origin is lost.

This occlusion of the meaning-origin, “technization,”[44] occurs in conjunction with two elements. First, the hypothetical-verificational character of the new science, which ascends to constructed ideal models and descends to compare these to empirical evidence, contains a deceptive iterative perfectibility. One begins to take the limit of this process as “‘ultimate’ true being, that it gives us a better and better ‘representation’ of what ‘true nature’ is.”[45] Second, the proliferation of algebraic method in physics’ formulae brings with it “almost automatically” an “emptying of meaning.”[46] This occurs through an exclusion of what Vieté called the final stage of algebra, the exegetic, which interprets the obtained formula as second intention in terms of the primary intentions (shape, number). Influenced by these two, the physicist lapses into a “technization” of his method and the idealized models achieved by it; he “[construes] them independently of their references to the lifeworld,” which is “to empty them of meaning.”[47] One must distinguish, then, between hypostatization, tolerable as method, and its technization.[48] Under the latter’s influence

. . . the reflection back upon the actual meaning which was to be obtained for nature through the technical method stops too soon. It no longer reaches far enough even to lead back to the position of the idea of mathematizing nature sketched out in Galileo’s creative meditation, to what was wanted from this mathematization by Galileo and his successors and what gave meaning to their endeavors to carry it out.[49]

When combined with a third element, “Galileo’s famous doctrine of the merely subjective character of the specific sense-qualities,”[50] the method becomes “a garb of ideas, or the garb of symbols of the symbolic mathematical theories, . . . It is through the garb of ideas that we take for true being what is actually a method . . . .”[51]

The sedimentation of technized science precludes the attempt to lead the individual scientist to reflect upon the original meaning of his mathematical-physical work. After all, “The professional who has dedicated his life to these sciences must . . . know best what he is attempting and accomplishing in his work.”[52] The scientist is blind to a broader context of truths beyond physico-mathematical ones.

While it is beyond the scope of this paper to provide Husserl’s argument in the remainder of Part II of Crisis, it follows from technization that the knower (scientist or learner) is occluded as the subject of knowledge: idealization applied to the natural world has led to a rift between the mind and its object. Furthermore, any attempt to study subjectivity in tradition objectifies it (psychologism). The divide between mind and world introduced by Descartes spawns failed transcendental and skeptical approaches to the ego as subject.[53] “This is the tragedy of modern mind which ‘solved the riddle of the universe,’ but only to replace it by another riddle: the riddle of itself.”[54] Husserl’s solution is to overcome the restrictions of the objective sciences (reasoning in “the life of the plane”) with a recovery of subjectivity (reasoning in “the life of depth”).[55]

This is the second major role of idealization, for the clarification of idealization as giving meaning to the origin of the objective sciences shows it to be caught up in subjective human achievements. Properly understood, idealization does not reveal that “science itself is ‘subject-relative,’” which the objective scientist would grant as a lamentable weakness, but rather that “the subject-relative, far from being the diminishing of objectivity, is the very condition for the possibility of the manifestation of the sense of the objective as a positive human experience.”[56]

Husserl begins this phase by noting that the objective sciences achieve

. . . a theoretical-logical substruction, the substruction of something that is in principle not perceivable, in principle not experienceable in its own proper being, whereas the subjective, in the life-world, is distinguished in all respects precisely by its being actually experienceable.[57]

Galilean science ‘builds-under’ the world given in common experience.[58] While these substructs cannot be experienced as the given world can be, they are nevertheless “‘grounded’ in the self-evidence of the life-world.”[59] The theoretic activity involved in making these substructions are “phenomena in the life-world,”[60] the achievements of the people who carry out such activities. This leads Husserl to ask:

The concrete life-world, then, is the grounding soil . . . of the “scientifically true” world and at the same time encompasses it in its own universal concreteness. How is this to be understood?[61]

This subjectivity of experience in the life world cannot be treated in the manner of objective science (exclusion of psychologism). This leads Husserl to the epoché of the objective sciences, a suspension “in regard to all objective theoretical interests, all aims and activities belonging to us as objective scientists . . . .”[62] As Husserl emphasizes here, this epoché of the attitude directed to carrying out the objective sciences is not a doubt of their validity. It is merely an abstention from their exercise for the purpose of approaching a solution to the problem of subjectivity.

This first epoché leads to the transcendental epoché. The middle term between the two, however, is the clarification of what Husserl terms the life-world a priori, what belongs to it as a general, non-relative structure, e.g., that it is, “Prescientifically . . . already a spatio-temporal world.”[63] The most fundamental apriority of the life-world, however, is as the context in which anything is given correlatively to understanding (§37). This leads to the full transcendental epoché and reduction to the transcendental attitude (§§38-55).[64] Hence, the clarification of idealization serves a third function, for it leads mediately to the second epoché and beginning of phenomenology.

After all this, what is life-world? “[T]he life-world . . . is not simply the world in which we live; it is the world we live in as contrasted to the world of exact science,” and “as named by phenomenology.”[65] Yet this can seem circular.[66] One must distinguish between: “life-world as naïvely appropriated and as appropriated critically.”[67] The former contains the bias of the technized, sedimented objective sciences, it is a ‘life lived in crisis.’ This begins to be removed by the epoché of objective sciences. As the first epoché leads to the second, the life-world can then be appropriated critically in retrospect.


A comparison of Husserl’s examination of idealization and St. Thomas’ defense of physics in De Trinitate shows the importance of understanding how reason affects what it knows in its very act of knowing. The premise for comparison is that the concept correlates of morphological essences are to those of exact essences as the consideration of the essence of a thing in total abstraction is to its consideration in formal abstraction.[68]

The essence of a natural substance considered in total abstraction, e.g., ‘man’ or ‘horse,’ includes the account of common but not individuating matter. This conclusion explains how men can know beings in matter and motion without falsifying their consideration. Plato’s account, however, errs by fallacy of the accident.[69] Since the species of ‘man’ or ‘horse’ is incorruptible, and the experienced, individual ‘man’ or ‘horse’ is generated and corrupts, he concludes from this that the eternality of the species is due to its separate existence. This is a fallacy of the accident for the species of a thing corrupts only per accidens, while the composite corrupts per se (‘man’ does not die, but ‘this man’ does). The failure to distinguish the per accidens corruption of the species in the individual composite from its per se incorruptibility in the intellect (due to its immaterial mode of reception), is thus a failure to properly distinguish how the man affects what he knows in knowing.

Husserl uncovers the Platonism of modern science, and corrects a similar fallacy. Taken with St. Thomas’ position on idealization,[70] this is a noteworthy supplement. Formal abstraction accounts for man’s ability to consider mathematicals without falsity. Since the mind can consider what is prior without what is posterior, and as “accidents accrue to substance in a certain order, for quantity comes first to it, then quality, then passions and motions,”[71] the mathematical consideration of quantity alone (formal abstraction) is a truthful act of reason. Insofar as Galilean physics methodically attains an indirect mathematization of accidents posterior to quantity,[72] it considers the physical world through such substructions, a methodically applied formal abstraction. These exact essences are per se to the mind, and the sense-plenum they substruct is per accidens to them as kinds of givenness. When technized, however, this method and its constructs become the “garb of ideas that we take for true being . . . .”[73] The mind’s mode of considering exact essences is taken for the being of things. Husserl’s correction in regard to the tradition of modern physics thus functions analogously to St. Thomas’.

It is important to understand idealization, for one will most likely err by inattentively considering it. Husserl sees that the technization of natural science leads to an unsolvable problem when one recognizes that “‘world’ is a validity which has sprung up within subjectivity . . . ,”[74] for the bond is no longer preserved between reason and what is. Care is required to restore reason in the world, and the world in reason.

[1] Edmund Husserl, The Crisis of the European Sciences and Transcendental Phenomenology: An Introduction to Phenomenological Philosophy, trans. D. Carr (Northwestern University Press: Evanston, 1970) 23. Hereafter, Crisis.

[2] Ibid., 3. Carr’s contention (see Crisis, “Translator’s Introduction,” xxix) that Husserl considered this explication of the way to transcendental reduction (the ontological way through the life-world) as definitive (for which he draws support from Crisis, §43) will not be considered here.

[3] I exclude a discussion of “teleological-historical” for two reasons: (1) it is more important to understand how “origin” connects to idealization in Husserl’s argument; (2) because the tension in Husserl’s presentation of phenomenology between origin and this unusual sense of history could not be satisfactorily explored here. The resolution of this tension has several difficulties. Carr wonders at its Hegelian roots (Crisis, “Translator’s Introduction,” xxxiii); Ricoeur presents four arguments for the incompatibility of phenomenological origin and history: (i) the latter is accidental to the concerns of the former, (ii) historical concern is eliminated by the transcendental reduction, (iii) it belongs to a consideration of phenomenological time to explain history as a given experience, not the converse, (iv) the intersubjectivity of phenomenology varies from that dealt with in history due to difference in attitude. (Paul Ricoeur, Husserl: An Analysis of His Phenomenology, (Evanston: Northwestern University Press, 1967), 145-150). Husserl in his earlier writings excluded consideration of history to begin phenomenology, but later allowed for it, Carr contends (ibid., xxxvii-iii), because of the need of ‘historical’ reflections to ground the philosophical epoché, which is prior to the transcendental epoché; hence, by discussing origin and idealization, I will be assuming this latter development, which appears to rename philosophical epoché as epoché of the objective sciences. The shift is justified by taking history in an unusual sense as a sort of eidetic reduction (Carr, ibid., xxxvi-ii).

[4] Husserl, Crisis, 6; also, ibid.: “The mere science of bodies clearly has nothing to say; it abstracts from everything subjective. As for the humanistic sciences . . . their rigorous scientific character requires . . . that the scholar carefully exclude all valuative positions, all questions of the reason or unreason of their human subject matter and its cultural configurations.”

[5] Robert Sokolowski, Pictures, Quotations, and Distinctions (Notre Dame – London: University of Notre Dame Press, 1992) 162-3.

[6] Husserl, Crisis, 11 (italics omitted).

[7] See ibid., Appendix VI, The Origin of Geometry, 353-78.

[8] Ibid., 353.

[9] See ibid., 360-1. Tradition is what one unpacks by examining history in its “unusual sense” (Origin, 354). See Patrick A. Heelan, “Husserl’s Later Philosophy of Science,” Philosophy of Science 54 (1987): 369: “[History in the unusual sense] is not the story of the past as past, but of the present as carrying forward in our own time projects shaped by past interests and events.”

[10] Husserl, Crisis, 24.

[11] Husserl, Origin, 361.

[12] See ibid., 367, “The inheritance of propositions and of the method of logically constructing new propositions and idealities can continue without interruption from one period to the next, while the capacity for reactivating the primal beginnings, i.e., the sources of meaning for everything that comes later, has not been handed down with it.”

[13] Husserl, Crisis, Appendix VII, The Life-World and the World of Science, 379. Also, ibid., §§35, 40.

[14] Husserl, Ideas I, trans. W. R. Boyce Gibson, (New York: The Macmillan Company, 1952), 52.

[15] See ibid., 103-4.

[16] See Husserl, Origin, 354, “The whole cultural world, in all its forms, exists through tradition.”

[17] Husserl, Crisis, 26, 27, respectively.

[18] Patrick A. Heelan, “Husserl’s Later Philosophy of Science,” Philosophy of Science 54 (1987): 376. It is important to note that this link is bidirectional. See James W. Garrison, “Husserl, Galileo, and the Processes of Idealization,” Synthese 66 (1986): 330: “The processes of idealization have two distinct directions: one ascending from the life-world, the other descending and applying to it.” While this use of ‘life-world’ must be qualified (see III, end), this bidirectionality obtains the Galilean hypothetical-verificational character.

[19] Husserl, Crisis, 25.

[20] Ibid., 25, 26, respectively.

[21] Ibid., 25.

[22] Sokolowski, Pictures, 158.

[23] See Husserl, Ideas I, 207-8: “The geometer is not interested in actual forms intuitable through sense, as is the descriptive student of nature. He does not, like the latter, construct morphological concepts of vague types of configuration, which on the basis of sensory intuition are directly apprehended, and, vague as they are, conceptually or terminologically fixed. . . . Geometrical concepts are “ideal” concepts, they express something which one cannot “see”; their “origin,” and therefore their content also, is essentially other than that of the descriptive concepts as concepts which express the essential nature of things as drawn directly from simple intuition, and not anything ‘ideal.’”

[24] Robert Sokolowski, Husserlian Meditations: How Words Present Things, (Evanston: Northwestern University Press, 1974), 78.

[25] Husserl, Crisis, 27.

[26] Ibid., 28.

[27] Ibid., 26.

[28] See ibid., p.51, and §§33-36.

[29] Ibid., 21.

[30] Ibid., 22.

[31] Alexandre Koyré, “The Significance of the Newtonian Synthesis,” in Problems in European Civilization: The Rise of Modern Science, ed. G. Basalla (Lexington, Mass.: Raytheon Education Co., 1968), 98; reprinted from Newtonian Studies (Cambridge, Mass.: Harvard University Press, 1965), 3-24.

[32] Husserl, Crisis, 23.

[33] Husserl seems most often to use ‘Galileo’ synecdochically for the philosophical position, not especially the man, which fits the mode of his eidetic, origin-driven view of history in Crisis. I accordingly use the abstract ‘Galilean’ to convey this. Husserl takes this notion of Galilean science from his colleagues at Göttingen school of mathematical physics; see Heenan, “Husserl’s Later Philosophy,” 371-373.

[34] Husserl, Crisis, 28-29. One recalls that the setting of Galileo’s Two New Sciences is an armory.

[35] Ibid., 29.

[36] Ibid., 29-30.

[37] Ibid., 31.

[38] Ibid., 37. See St. Thomas, Super Boetium de Trinitate, q.5, a.3, ad v & vi.

[39] Ibid., 33.

[40] Ibid., 35.

[41] Ibid., 37, 36, respectively. Husserl does not expound cases of idealization as regards Galileo himself. See Garrison, “Husserl, Galileo, and the Processes of Idealization,” 333-5, where Galileo’s analysis of freefall is an example. Galileo idealizes the medium of fall to one that offers no resistance in order to argue that all bodies fall at the same rate.

[42] Husserl, Crisis, 52-3.

[43] See Koyré, “The Significance of the Newtonian Synthesis,” 99.

[44] Husserl, Crisis, 46.

[45] Ibid., 42. The direction of Husserl’s claim here must be clarified. He is warning against a naïve scientific realism, not arguing against it as such (as long as it is meaning as a method is retained). Some mistake this, see G. Gutting, “Husserl and Scientific Realism,” Philosophy and Phenomenological Research 39 (1978): 42-56; and the reply by J. Rouse, “Phenomenology and Scientific Realism,” Philosophy of Science 54 (1987): 222-32.

[46] Ibid., 44, 46.

[47] J. Rouse, “Phenomenology and Scientific Realism,” 224.

[48] See Husserl, Crisis, 53.

[49] Ibid., 48.

[50] Ibid., 54

[51] Ibid., 51.

[52] Ibid., 57.

[53] This failure, when “. . . joined with the project of confirming objective science, explains the strange destiny of Cartesianism, which engendered the rationalism of Malebranche, as well as that of Spinoza, Leibniz, and Wolff [from whom Kant takes his beginnings, §25ff], all turned entirely towards absolute knowledge of being in itself, and also engendered skeptical empiricism, which draws out all the consequences of the psychologistic interpretation of the cogito [Locke, Berkley, Hume]. The first current eliminated the motif of doubt and the ‘reduction to the ego’; the other grossly deluded itself about the nature of founding subjectivity and destroyed truth entirely [Hume, §23].” Ricoeur, Husserl, 165.

[54] Alexandre Koyré, “Significance of the Newtonian Synthesis,” 104.

[55] Husserl, Crisis, 120-1, 100, 118ff, respectively. Kern labels this realization (plane-depth) the end of the “first thrust” in Husserl’s advance towards the ontological way to reduction through the life-world; Iso Kern, “The Three Ways to the Transcendental Phenomenological Reduction in the Philosophy of Edmund Husserl,” Husserl: Expositions and Appraisals, ed. F. A. Elliston and P. McCormick (Notre Dame, ID: University of Notre Dame Press, 1977), 142ff.

[56] James Dodd, Crisis and Reflection, (Dordrecht: Kluwer Academic Publishers, 2004), 150.

[57] Husserl, Crisis, 127.

[58] See ibid., 128-9. Consider the substruction of experienceable space and time, e.g., “Minkowski’s ‘world’ . . . a four-dimensional Euclidean space (with imaginary time coordinate) . . . ,” which provides the basis of the Lorentz transformation equations in the special theory of relativity through a four-dimensional version of the Pythagorean theorem with a time constant √-1(ct) where c = speed of light and t = time as measured in the given frame of reference; see Albert Einstein, Relativity, trans. R. W. Lawson (New York: Wing Books, 1961), 140.

[59] Husserl, Crisis, 130.

[60] Kern, “The Three Ways,” 142.

[61] Husserl, Crisis, 131.

[62] Ibid., 135.

[63] Ibid. It is important to note that this a priori of the life world is not a conceptual framework that is “transported” into the mind in knowing.

[64] See Kern, “The Three Ways,” 143-44.

[65] Sokolowski, Pictures, 155.

[66] See Carr, Crisis, “Translator’s Introduction,” xli: “Husserl frequently insists that the theories of our scientific culture ‘flow into’ the life-world; compounded of such theories, it forms the traditional Boden of both our theoretical and our extratheoretical life and is thus certainly pregiven. But in this case it could not be described as pretheoretical. This seems to contrast sharply with repeated descriptions of the life-world as one whose very essence is to envelop or underlie all theoretical interpretations of it.”

[67] Heelan, “Husserl’s Later Philosophy of Science,” 380.

[68] See St. Thomas, Super Boetium de Trinitate, q.5, a.3 (Roma – Paris: Commissio Leonina - Éditions du Cerf, 1992) 144-151. I emphasize the comparison (correction of a fallacy) while submitting contrasts here: (1) The concept correlates of morphological essences have a broader range than essences considered in total abstraction, for morphological essences retain reference to the subject, and can include non-substances, whereas ideal essences seek to prescind from the subject and attain perfect objectivity. However, insofar as morphological essences and exact essences are differentiated by the former’s inability to consider measurable essential parts, I will use the analogy. (2) Husserl’s idealization is a process that spans many categories, involving the practical, experiential, and rational aspects of arriving at such a knowledge (and borrows heavily from calculus), while St. Thomas considers only the formal account of the act of the intellect. Hence, under the latter’s consideration, if the intellect “fixed” or “perfected” quantitative essences through formal abstraction, this abstraction would be false. This abstraction would also be present (granted in a very confused degree) even in small children; what Husserl’s account brings out are the various mature experiences required to formulate geometric statements scientifically. “Idealization” for St. Thomas, therefore, refers only to the end product of what Husserl’s idealization attains. (3) I will abstain from considering here the validity of indirect mathematization for St. Thomas’ conception of physics, taken strictly as a speculative science (note, e.g., the difficulties in accepting Galilean void); but remark that such an “indirect mathematization” would take on the aspect of a conglomerate: an intermediate science conjoined to an art (experimental method). This agrees (at least prima facie) with Husserl’s characterization of idealized substructs within the method of modern physics.

[69] See St. Thomas, de Trinitate, q.5, a.2, c. “This failure occurs because [Plato] did not distinguish what is per se from what is secundum accidens. In fact many are deceived, even the wise, according to the accidental, as is said in Sophistical Refutations I.” (Leon.50.143:62-66).

[70] See fn.67, (2).

[71] St. Thomas, de Trinitate, “[Set] accidentia superueniunt substantie quodam ordine: nam primo aduenit ei quantitas, deinde qualitas, deinde passiones et motus.” (Leon.50.148:188-191).

[72] See fn.67, (3).

[73] Husserl, Crisis, 52.

[74] Ibid., 96.

Here is the term paper which I wrote for my class on the "De Anima," entitled "Utilitas Psychologiae: An Investigation Into the Usefulness of the Science of Soul for the First Philosopher"

With characteristic swiftness and lucidity, St. Thomas draws out of the prooemium to the De Anima the Philosopher’s intent to render his student benevolent by an exposition of the utility of the science of soul.[1] While it may seem odd that one speculative science is useful to another, psychology is so, for, “‘It gives occasions to all other notable parts of philosophy.’”[2] One most eminent part is first philosophy, for, “we are not able to come to knowledge of the divine and highest causes except by those which we first acquire of the power of the intellect.”[3] Naturally one asks: how exactly does psychology accomplish this? In reply, our inquiry will take three parts. First, the question will be determined more precisely. Second, from these precisions, the road from psychology to first philosophy will be found out. From this, an instance of such an “occasio” will be advanced: the psychologist develops the notions of potency and act as received from the general definition of motion[4] in his investigation of the grades of living things. This road of investigation leads him to the doorstep of first philosophy.


St. Thomas’ only suggestion about to the nature of the occasio provided to first philosophy is preparation to know divine and highest causes. By examining the other occasiones we can understand this one more fully.[5] First, for ethics, a lack of knowledge of the powers of the soul leads to an imperfect knowledge of virtue, for the excellence of these powers is integral to the account of virtue.[6] However, only those parts “[are] to be used” that show “that a certain part of the soul is rational,” i.e., capable of the command required for voluntary action, and “a certain part irrational . . .”[7] and thus capable of obedience. Details such as the rational or real separation of the powers can be ignored. Such imprecision is fitting, for ethics requires only factual knowledge of the powers’ accounts to teach human happiness.[8] Second, since the greater part of nature is ensouled[9] and soul is the principle and source of movement, physics as a speculative science requires psychology as a perfective part. Therefore, generally, an occasion provides beginnings to another science according to the scientific mode of such a receiver.

An explicit connection between psychology and first philosophy is found in St. Thomas’ prooemium to De Sensu. In comparing the general study of soul (the most abstract) to the posterior studies in biology that consider soul as enforming body and the various species of living beings, which are more concrete, and hence more particular,[10] St. Thomas excepts one grade of living being from this more concrete mode of study:

However, of these [grades of living beings], the intellect certainly is the act of no part of the body, as is shown in De Anima III. Whence, it cannot be considered through concretion or application to body or to some corporeal organ, for its greatest concretion is in the soul. Moreover, its highest abstraction is in the separate substances, and therefore Aristotle did not write, besides the De Anima, a book on the intellect and the intelligible (or if he had done so, it would not pertain to natural science, but rather to metaphysics, to which the consideration of separate substances belongs.)[11]

While the term ‘metaphysics’ is used here, and not first philosophy, this difference is nominal.[12] This passage, then, indicates that the proof of the human intellect’s immateriality is the beginning (in some way) of another science, for psychology cannot treat of separable being within its own scientific formality. Hence, the road psychology takes to arrive at this point is one aspect of its utility.

To understand the nature of this road, we must recall the difference in the mode of definition between physics and metaphysics. Physics studies beings in matter and motion and defines in a corresponding mode, while metaphysics knows being qua being and abstains from matter and motion as such in its mode of defining.[13] Further, physics demonstrates through all four causes, but metaphysics though only three.[14] Since man knows corporeal things first, and only those comprehensively,[15] the principles of his knowledge of such things (definitions) are at first insufficient as principles of knowledge of beings existing apart from matter or motion. For psychology (and consequently the psychologist) to provide occasions to first philosophy,[16] it must extend its principles. As St. Thomas’ prooemium to the De Sensu implies, this occurs along with the scientific discovery of grades of living beings that require such extensions in order to be known: the vegetative, sensitive, and intellectual souls.

Now, among the inferior living things (as opposed to separate ‘living’ beings) there is a two-fold manner of being: one is material, in which things are contracted to a single species; the other is immaterial, meaning that such things can receive other species in addition to their own.[17] This immaterial being is itself two-fold:

. . . for one is completely immaterial, namely intelligible being, for in the intellect a thing has being both without matter and the individuating conditions of matter, and also apart from a corporeal organ. However, sensible being is a mean between the two, for in sense a thing has being apart from matter, yet apart from neither the individuating conditions of matter nor apart from a corporeal organ, for sense is of particulars, while the intellect is of universals. And it is with respect to this twofold being the Philosopher says in the third book of this [treatise] that the soul is in a certain way all things.[18]

Hence, there are two levels above material living being—to which the vegetative soul is limited—and three grades in all. The vegetative soul retains all three conditions: an enmattered form, consequent individuating conditions, and an organic body. Sensitive material souls can receive additional sensible forms without matter, but still receive according to individuating conditions and with organs. The intellectual soul, however, “a form of matter but not a material form,”[19] receives being and additional forms apart from all three conditions.[20] Granted that this mode of ranking is metaphysical (for to consider an immaterial order among beings as such falls under a metaphysical mode of definition), nonetheless, it indicates the two key scientific moments in the road from psychology to first philosophy: the consideration of potency and act as belonging to sensation (DA II.5), and the analogous discussion about the intellect (DA III.4).[21]


The first, De Anima II.5, serves as preamble to the treatise on the sensitive soul. St. Thomas marks three stages in the argument: first, it is shown that the senses admit of being in potency and in act; second, precisions are advanced by illustration from the intellect concerning the manner of reduction from potency to act; third, these precisions are applied to sensation.[22] These can be treated in four parts: first, the reason that the extension must be made; second, the preparation to understand the extension; third, the distinction itself; and finally, how this leads to the first grade of immaterial being.

What demands this extension as solution is the problem that entangled the ancient physicists, who attempted to explain sensation by alteration. To approach a resolution, Aristotle first what notes most characterizes the case: “Sensation occurs to something being moved and suffering.”[23] The opinions of his predecessors are mentioned to frame the query for the sake of the learner: “Moreover, some even say that like suffers by like,”[24] which he states is only qualifiedly true, alluding to De Generatione I.7.[25] This position of the ancients concerning alteration generally serves as a point of departure for the more particular problem of alteration in sensation, for it specifies to “like is sensed by like.”[26] Now, alteration strictly speaking is change from one qualitative species to the intermediate or contrary within the same genus: what is cold becomes warm or hot.

Given this beginning, in what way is sensation alteration? The ancient view, that sensation is alteration simply, where a like thing senses its like, cannot be true for this reason at least, that the need for something beyond the sense powers to cause actual sensation would be obviated: the sense power, like itself, would cause actual sensation of itself.[27] Since some otherness is required, the senses are in potency towards their objects. Furthermore, they are only intermittently in act, for a sleeping man and a waking man are both called sensing, the former in potency and the latter in act. This conclusion (that the senses admit of both act and potency) raises the issue of extension. How are the senses said to be in act when they suffer something from the sensible object? Recalling the received definition of motion from the Physics (“. . . as was said in another place.”), Aristotle points out that sensation can be called a sort of motion, although he insists that this is a preliminary and imprecise way of speaking.[28] St. Thomas notes that, “by this that [Aristotle] says ‘First,’ he indicates that after a certain while he will supply some things to show how sense becomes actual.”[29] Aristotle’s intention here is that “concerning both potency and act a distinction must be made, for now we are speaking of them simply.”[30] Aristotle thus warns his student to be attentive.

The preparation for this distinction is the second step in Aristotle’s argument (417a21–417b16). This is accomplished “using the intellect as an example.”[31] This example, by considering how men speak about knowers and knowing, distinguishes three stages: the ability to know that follows upon human nature, the state of actual consideration, and the in-between state, or the acquired ability to consider knowledge. Thus, a man is at first ignorant of the science of grammar, but able to learn it. Once he learns it, he can consider it at will. This yields the traditional “triple scheme”[32] of first and second potency and actuality. However, since the science of grammar is preserved in the active grammarian, these three stages are unlike the act and potency involved in substantial and accidental (take alterative) change. In the latter case, the second potency of a subject is the disposition of the present alterable quality, which is destroyed when altered: a cold thing’s potency to be hot, once actualized, is gone, and can only be regained by return to the contrary. By contrast, the habit of science is a disposition which, when in act, is not lost in comparison to its activity. Not thinking is not a strict contrary to thinking. The habit principles consideration, and it merely progresses “into itself.”[33]

Hence, while “one sort” of alteration “is a certain corruption by the contrary, the other however is rather [a] a saving of it that is in potency by that which is in act and [b] thus by a similar thing just as potency has itself to act.”[34] With this obscure sentence Aristotle at once reveals the difference and similarity involved. The difference [a] is this: “that which is in act” (a grammarian considering) preserves “it that is in potency” (the habit of grammar), unlike the potency to be hot, which is exhausted when actualized. The similarity [b] is that the first still bears to the second the relationship of potency to act. The difference obtains the extension, while the similitude retains the account to motion. Whence it is not alteration strictly, but rather another kind of alteration.

The third and final step (417b6–418a6) St. Thomas describes thus, “What [Aristotle] had said about the intellect he fits to the senses.”[35] After the determination is applied, it is clarified by giving exceptions. The application is as follows:

The first change of the sensitive, however, comes about by generation. But when a thing is generated, it has sensing already, just as knowledge; which [sensing] however according to act is said similarly to considering.[36]

In the analogy, the habit of knowledge and its actual consideration align with the generated animal soul (with its sense power) and the exercised sense power. As the ability to sense is not lost during sensation, the extended, qualified notion of alteration fits, for “the sensitive in potency is like the sensible already in act, as was said.”[37]

This conclusion is qualified, for sensation concerns particulars and science universals. Additionally, the former are “outside the soul,” while the latter are “in a way inside;”[38] hence the former objects cannot be actually considered at will as the latter can. Therefore, while Aristotle actually achieves in DA II.5 three distinctions in alteration (namely among the material, sensitive, and intellectual), the difference between intellect and sensation must be made clearer, “namely in the third book where [Aristotle] treats of the intellect and of the comparison of the intellect to sense.”[39]

However, due to this last mark, an objection arises. The way in which the extension has been made seems circular, for psychology’s consideration of the senses is a preamble to the consideration of intellect—what is determined about sensation is later used to understand intellection (DA III.4, 429a13ff). However, no vicious circle exists. At this point in the scientific order of psychology the difference between intellect and sensation has not been argued for (this comes at III.3, 427a17-b14). Whence, the experience used to manifest the difference between material alteration and sensitive operation need not be known distinctly in itself, only better known to us. Now, the experience of learning and considering is more known to us, for it occurs at will and is interior. Thus Aristotle uses it in the extension, but marks these very differences at the end of his treatment. When the extension is used to examine each particular sense, these examinations start from other more known experiences. Thus, no vicious circle obtains.

It remains to show how these distinctions lead to the first grade of living being that St. Thomas calls immaterial. Now, in the De Anima’s subsequent particular considerations of each sense, the account of each power is determined via its object. Whence, each power is of a sort that is actualized by its proper object in the mode of that second actuality which preserves the power: the reception of the sensible species is such that it preserves the potency ordered to such reception. However, this reception must take place without the matter of the object acting upon the sense power, for such a manner of material alteration was excluded by the arguments in II.5. The ordinary mode of alteration, as experience shows, consumes the potency towards the contrary once the contrary is led into act. The sensitive mode of alteration must involve a different kind of potency since this does not occur. In view of this, Aristotle begins his summary of the treatise on the external senses by observing that, generally, “sense is what is receptive of the species without the matter . . . .”[40]

This is clear also from St. Thomas’ concern in the same place, for, “it seems that this is common to all passion,” namely to be receptive of the form without the matter:[41] for even “air does not receive matter from the fire acting upon it, but form.”[42] However, the mode of reception of form depends upon the disposition of the receiving matter. The reception of sensible qualities in things and in sense powers is thus differentiated:

. . . the senses receive the form without the matter, because the form has a different mode of being in the sense [power] and in the sensible thing, for in the sensible thing it has natural being, but in the sense [power] it has intentional or spiritual being.[43]

Hence, reception “without the matter” must be taken according to another manner of material disposition. The first level of immaterial being is thus established, for metaphysics (in its mode of definition) can name such reception immaterial.[44] Psychology (in its mode) must name this reception with reference to matter, i.e. as regarding the preservation of the potency in question, defining the intrinsic formal cause of the enmattered power by denomination from its extrinsic formal cause: the object.[45]

Since the account of intellect is preliminarily determined through a comparison to sensation, the claimed extension of potency and act regarding intellection is made easily. With this extension comes the second grade of immaterial being. The beginning of this further distinction is DA III.4, the treatment of the possible intellect. The agent intellect will be excluded from the current consideration, for whatever applies to the possible intellect is found even more so in the agent, for the agent is nobler than the patient.[46] Further, the detailed argument for the difference between sensation and intellection will be assumed (DA III.3, 427a17-b14).[47]

The first half of DA III.4 (429a10-b9) “shows the nature of the possible intellect”[48] in two parts: first, the nature of the power, and second, “how it is reduced to act.”[49] While intellect occupies Aristotle from III.4-7, he wastes no words up front; he “reaches these determinations about the mind and its operation by reference to its object” namely all things, before the discussion “becomes more specific,” later on (429b10ff).[50] Since the nature of the intellect is obtained from its object within the first half of III.4; this part can be focused on while maintaining completeness. It has three sections:

[Aristotle] first proposes the likeness of intellect to sense; second, from such likeness he concludes to the nature of the possible intellect. [T]hird, he shows the difference between intellect and sense from the things he had proved of the intellect . . .[51]

With an air of déjà vu, the intellect’s similitude to sense serves as the entry-point to understanding its nature. This amounts to a simple analogy: “[J]ust as the sensitive is to sensibles, likewise is the intellective to the intelligibles, for either one is in potency to its object and receptive of it.”[52] However, and St. Thomas reminds the reader of this (“[E]ven sensing, as was said above in Book II, is not properly a passion.”[53]), the ‘suffering’ of the intellect must be understood analogously; further, as sensation and intellection differ, this analogous sense of passion may require distinction.

This second distinction is confirmed once the nature of the possible intellect is shown. In short, “because [the intellect] understands all things, it is unmixed.”[54] Since the reach of mind is so broad, as power it must be a proportionate receptacle, lacking in any incumbent species. Hence, the intellect “is not something bodily or mixed with bodily things . . . nor does it have a corporeal organ,”[55] for in either case its cognitive range would be hindered.

This unmixed nature of the intellect allows the difference between it and the senses to be shown, which provides the complete account of the two grades of immaterial being. For the senses powers, as acts of organs, have a certain “annexed material change,”[56] and are thus impaired in their reception of lesser sensibles after having received an intense sensible species (think of the ‘ghost colors’ seen after staring at bright objects). Further, they cannot sense the excessively sensible without damage or destruction. The intellect, however, understands lesser intelligibles better, and not worse, “when it understands something greatly intelligible.”[57]

This difference between sense and intellect in the reception of their respective objects (borne out by experience) indicates a difference in their ‘material’ dispositions. On the one hand, the preservation of the potency of the sense powers is limited or destructible (noise can temporarily or permanently deafen); on the other hand, the preserved potency of the intellect is not. Hence, “lest some believe that there is the same grade of impassibility in sense and intellect,”[58] this shows that “since [the intellect] lacks an organ, it is thus passible neither per se nor per accidens.”[59] This distinct grade of reception corresponds to the second immaterial grade of being indicated by St. Thomas, for, since the intellect is immaterial, it must receive other forms accordingly.


We now see how the road through psychology provides occasions for first philosophy. Insofar as psychology establishes the specific account of the sensitive and intellectual souls, and realizes an extension of the physicist’s notions of potency and act, it touches upon grades of being that it can only name as less passible than its first notion of material change. However, the metaphysician or first philosopher, who defines in an immaterial mode, can name these as diverse grades of being as being, as St. Thomas does: they comprise a two-fold immaterial being, intelligible and sensible.

Aristotle, in his prooemium, does not render his students benevolent in vain. Psychology indeed has its pride of place among the parts of physics. Just as the general physicist perfects his science by demonstrating the First Mover, which he shows to be “partless”[60] and outside his subject genus, so also the general psychologist reaches the height of his considerations when proving the immateriality of the intellectual soul. While the former demonstration shows the existence of a complete substance, and the latter of a substance qualifiedly complete, these qualifications can only be given by metaphysics, for its purview is substance as such. The metaphysician also sees that the physicist reaches a total separation from matter and a perfect distinction between metaphysics and physics, but the psychologist only a partial one, as the human soul is an incomplete substance. Nevertheless, the psychologist’s demonstration is somewhat superior, for it shows the formal cause of a separate being that is still part of physics’ subject, even if this very demonstration also shows that man is a part of the subject as a “limit” is part of the thing.[61] The philosopher locates himself, via soul, “on the border of corporeal and separate substances.”[62] He simultaneously reaches wisdom’s doorstep, but with “equipment” sufficient to continue “the journey to the whole of truth.”[63]

[1] See St. Thomas Aquinas, Sentencia Libri de Anima, c.1 (Roma – Paris: Commissio Leonina – J. Vrin, 1984) t.45, v.1, p.3-7. I will call this science of soul ‘psychology,’ meaning primarily that integral part of natural science that first studies the soul in itself “as if in a certain abstraction.” See St. Thomas, “. . . primo quidem considerauit de anima secundum se quasi in quadam abstractione . . . . Prima igitur consideratio continetur in libro De Anima . . .” Sentencia Libri de Sensu et Sensato (Roma – Paris: Commissio Leonina – J. Vrin, 1985) (45/2.4:40-1, 47-8).

[2] St. Thomas, SLDA, “‹‹Ad omnes enim partes philosophie insignes dat occasiones.››” (Leon.45/1.5:117-8); Gauthier notes that St. Thomas is quoting Themistius, see fn.5 below.

[3] Ibid., “Quia . . . non possumus deuenire in cognitionem diuinorum et altissimarum causarum nisi per ea que ex uirtute intellectus primo acquirimus.” (Leon.45/1.5:118-122).

[4] This definition is established by the general introduction to physics, i.e. the properly first, holistic, and general study of mobile being (Aristotle’s Physics).

[5] St. Thomas follows other commentators in detailing such occasions in Aristotle’s prooemium, although his specifics vary somewhat from others in the tradition. Themistius, comparing the habit of psychological science to equipment needed on the journey to all truth, holds that, “. . . if [the soul] knows itself, it is credible on other [matters] too; but if misled about itself, on what else could it be considered credible?”a He gives the same uses of psychology to ethics and natural science, and adds only that the soul may be the source of movement “for all bodies,” but does not mention here his view on the intellect. Averroes distinguishes between a strict utility towards physics and that offered other sciences: towards concrete biology, psychology is not merely useful, but necessary, whereas it provides assistance (iuvamentum) to other sciences in three ways. One is as the “noblest” part of a science, due to the nobility of its object. Another is a “common help” since it provides knowledge of causes. He also notes the help provided to moral science and to divine science, by giving beginnings: “Divine science however, takes from it the substance of its subject. Indeed it will be shown here, seeing that the separate forms are intelligences . . .”b

a Themistius, On Aristotle’s On the Soul, trans. R. B. Todd (New York: Cornell University Press, 1996) 15 (1,24). b “Divinus autem suscipit ab ea substantiam sui subiecti. Hic enim declarabitur quoniam forme abstracte sunt intelligentie . . .” Averroes, Commentarium Magnum in Aristotelis De Anima, ed. F. Stuart Crawford (Cambridge, Mass.: Medieval Academy of America, 1953) (5:28-30).

[6] St. Thomas, SLDA, “Si uero attendatur quantum ad moralem, non possumus perfecte ad scienciam moralem peruenire nisi sciamus potenciis anime; et inde est quod Philosophus in Ethicis attribuit quaslibet uirtutes diuersis potenciis anime.” (Leon.45/1.6:122-6). See Aristotle, Nicomachean Ethics, 1102a16-31.

[7] St. Thomas, Sententia Libri Ethicorum (Romae: Ad Sanctae Sabinae, 1969), “est utendum . . . quod quaedam pars animae est rationalis, quaedam irrationalis . . . .”(Leon.47/1.69:103-4).

[8] See Ibid., (Leon.47/1.68:72-85).

[9] Following the classical view that the realm of nature (phusis) is limited to the sub-lunar sphere. Therefore, of such species, the majority of them are alive. To investigate a modern recovery of this position would be beyond the scope of this paper.

[10] See St. Thomas, SLDS, c.1, (Leon.45/2.4:41-7).

[11] Ibid., “Horum autem intellectus quidem nullius partis corporis actus est, ut probatur in III De anima; unde non potest considerari per concretionem uel applicationem ad corpus uel ad aliquod organum corporeum: maxima enim concretio eius est in anima: summa autem eius abstractio est in substanciis separatis; et ideo preter librum De Anima Aristotiles non fecit librum de intellectu et intelligibili (vel si fecisset, non pertineret ad scientiam naturalem, sed magis ad methaphisicam, cuius est considerare de substantiis separatis.)” (Leon.45/2.5:68-79).

[12] See John F. Wippel, Metaphysical Themes in Thomas Aquinas (Washington DC: CUA Press, 1984) 55-67, “‘First Philosophy’ According to Thomas Aquinas,” where he argues that divine science’s various names signify one science from diverse aspects or accounts. The consideration of the human intellect as immaterial has the notion of “metaphysics” insofar as it is posterior to physics in the order of sciences with respect to us, and the notion of “first philosophy” insofar as it is a separate being (albeit the lowest and only incompletely immaterial).

[13] See St. Thomas, Super Boethium de Trinitate, q.5, a.1, 2, &4; also SLDA, I.2, (Leon.45/1.11-2); also De Unitate Intellectus contra Averroistas, (Roma: San Tommaso, 1976) c.1, (Leon.43.297:514-8).

[14] The material cause is considered only under the account of potency, which, along with act, divides being per se, and thus falls under the scope of metaphysics.

[15] See St. Thomas, Summa Theologiae, Ia., q. 84, a. 7, c., “Huius autem ratio est, quia potentia cognoscitive proportionatur cognoscibili . . . Intellectus autem humani, qui est coniunctus corpori, proprium obiectum est quidditas sive natura in materia corporali existens.” (Leon.5.325). See also ST, Ia., q.88, a.2; Expositio Super Boethium De Trinitate, q. 1, a. 3, c.

[16] It must be recalled that psychology is properly a part of physics (see DA I.1). Hence, it considers soul insofar as it is a form of matter and principle of motion. How this extension retains the unity of psychology within physics will become clear. Also, it must be kept in mind that the physicist’s naming and knowledge of corporeal things that have greater degrees of immateriality is, strictly speaking, negative.

[17] See St. Thomas, SLDA, II.5, (Leon.45/1.88:55-70).

[18] Ibid., “. . . nam quoddam est penitus inmateriale, scilicet esse intelligibile, in intellectu enim res habens esse et sine materia et sine condicionibus materie indiuiduantibus et etiam absque organo corporali; esse autem sensibile est medium inter utrumque, nam in sensu res habet esse absque materia, non tamen absque condicionibus materie indiuiduantibus neque absque organo corporali; est enim sensus particularium, intellectus uero uniuersalium; et quantum ad hoc duplex esse dicit Philosophus in III huius quod anima est quodam modo omnia.” (Leon.45/1.88:70-83)

[19] B. C. Bazan, “The Human Soul: Form and Substance? Thomas Aquinas’ Critique of Eclectic Aristotelianism” Les Archives d'histoire doctrinale et littéraire du Moyen Âge, 64 (1997): 95-126. See St. Thomas, Quaestiones Disputatae de Anima (Roma – Paris: Commissio Leonina, 1996) q.1, 2. Bazan’s thesis is qualified by methodological studies; see M. J. Sweeney, “Soul as Substance and Method in Thomas Aquinas’ Anthropological Writings,” Les Archives…, 66 (1999): 143-187.

[20] How the intellectual soul is receptive of being in the sense meant here is proved in metaphysics. It does so receive, for it is in potency towards its act of being (esse). See St. Thomas, QDA, q.6, “Cum igitur anima sit quedam forma per se subsistere potens, est in ea compositio actus et potentie, scilicet esse et quod est, non autem compositio materie et forme.” (Leon.23.51:255-8). The major premise is that all subsistent forms have a composition of potency and act, excepting God.

[21] In the sequel, the two central methodological principles of physics will be at work (See Physics, I.1, 184a17-24 and De Anima, II.4, 415a15-24, respectively). The first is a progression from the more to less general. Psychology assumes the general definition of motion (Physics III.1-3) and must determine how soul is such a principle of the motion in living beings, a more specific kind of mobile being. Second, the account of the essence and powers of this soul must come through that of objects and acts. Thus precisions are achieved from consideration of the objects and operations of sensation and intellection, which require a subject that does not principle motion in the usual sense.

[22] St. Thomas, SLDA, “. . . ostendit quod sensus sit in potencia; secundo quod quandoque est in actu . . .” (Leon.45/1.108:39-40); “. . . distinguit potenciam et actum et ostendit quomodo diuersimode aliquid educatur de potencia in actum, utens exemplo intellectu . . .” (Leon.45/1.110:5-7); and “. . . ostendit propositum circa sensum . . .” (Leon.45/1.110:8).

[23] Aristotle, De Anima, 416b33-34, “Sensus autem in moueri aliquid et pati accidit . . .” (Leon.45/1.107). We shall use the translatio nova of De Anima, as we are attempting to follow Aristotle through St. Thomas.

[24] Ibid., 416b35, “Aiunt autem quidam et simile a simili pati.” (Leon.45/1.107).

[25] See Aristotle, De Generatione et Corruptione, 323b1-324b24. St. Thomas notes, as Aristotle does in DA 417a17-21, that it is qualifiedly true for “id quod patitur a principio dum patitur est contrarium agenti, set in fine quando iam est passum est simile; agens enim agendo assimilat sibi paciens.” (Leon.45/1.108:33-6). Commentators both ancient and modern agree to the reference: Gauthier includes Themistius, Averroes, St. Albert, and two anonymous ones; see also M. Burnyeat, “De Anima II.5,” Phronesis, 47 (2002): 38. “It is entirely appropriate, then, that Aristotle’s next move . . . is to send us to De Generatione et Corruptione I 7 for a general account of [the ancients’ mistake.]” Burnyeat laments that a lack of attention to cross-references has caused many misinterpretations, see 31-2.

[26] St. Thomas, SLDA, “. . . quod simile simili sentitur.” (Leon.45/1.109:120)

[27] As a sign of the unity of this portion of psychology with the more general treatment of alterative motion, we can notice with Burnyeat (“De Anima II.5,” 39-40) the similarity of Aristotle’s second argument presented here (417a3-6) with that in De Generatione at (323b21-3), against the more general position.

[28] Aristotle, DA, 417a16, “. . . sicut in alteris dictum est.” (Leon.45/1.107). See Aristotle, Physics III.1, 201a11-2. Motion is the actuality of what exists in potency as such, which entails that it is the act of the imperfect, for it exists only while the potency of the subject is being reduced into act without remainder. Indeed, the burden of the current argument is to establish that that ‘motion’ which is sensation is the act of something perfect, i.e. whose potency remains or endures.

[29] St. Thomas, SLDA, “Per hoc autem quod dicit ‹‹Primum››, significant quod quedam alia postmodum subdet ad ostendendum quomodo sensus fiat in actu.” (Leon.45/1.109:114-117).

[30] Aristotle, DA, 417a21-22, “Diuidendum autem et de potencia et actu est. Nunc enim simpliciter dicimus que habemus de ipsis.” (Leon.45/1.110)

[31] St. Thomas, SLDA, “. . . utens exemplo intellectu . . .” (Leon.45/1.110:7).

[32] Burnyeat, “De Anima II.5,” 48.

[33] Aristotle, DA, 417b6, “. . . in ipsum . . .” (Leon.45/1.110).

[34] Aristotle, DA, 417b2-4, “. . . aliud quidem corruptio quedam a contrario, aliud autem salus magis eius quod potencia ab eo quod est actu et simili sic sicut potencia se habet ad actum.” (Leon.45/1.110).

[35] St. Thomas, SLDA, “. . . quod dixerat de intellectu adaptat ad sensum.” (Leon.45/1.114:4).

[36] Aristotle, DA, 417b16-18, “Sensitiui autem prima quidem mutatio fit a generante; cum autem generatum est, havet iam sicut scienciam et sentire; quod autem secundum actum similiter dicitur ipsi considerare.” (Leon.45/1.114).

[37] Ibid., 418a3-4, “. . . sensitiuum potencia est quale iam actu sensibile, sicut dictum est.” (Leon.45/1.114). It is absolutely crucial to recognize here that it is the capacity to see, hear, etc., that is shown to be a preserved potency, and not whatever concomitant material changes are annexed to such acts (retinal chemical alterations, eardrum vibrations). The sensitive experience and objects themselves are in question, not their corporeal underpinnings. Thus, this conclusion is prior to the issue of concomitant material changes, much debated by Thomists and Aristotelians alike, for the sense powers, certain forms, must be understood before their matter (organs) following the proper order of physics: the less to the more concrete.

[38] St. Thomas, SLDA, “. . . sunt extra animam. . . . quodam modo sunt in anima.” (Leon.45/1.115:46, 49).

[39] Ibid., “. . . scilicet in III ubi agetur de intellectu et de comparatione intellectus ad sensum.” (Leon.45/1.115:62-3).

[40] Aristotle, DA, 424a18-9, “. . . sensu quidem est susceptiuus specierum sine materia . . .” (Leon.45/1.168).

[41] St. Thomas, SLDA, “. . . uidetur hoc esse commune omni pacienti . . . non enim aer recipit ab igne agente materiam eius, set formam.” (Leon.45/1.169:18).

[42] Ibid., “(Leon.45/1.169:23-4).

[43] Ibid., “. . . sensus recipit formam sine materia, quia alterius modi esse habet forma in sensu et in re sensibili: name in re sensibili habet esse naturale, in sensu autem habet esse intentionale siue spirituale . . .” (Leon.45/1.169:52-6).

[44] It seems that metaphysics does so only in its peculiar mode of sapiential retrospection: in this comparison, the intellect (a wholly immaterial cognitive power) is taken as the first analagate, and the senses are compared to it insofar as they fall short of its spiritual mode of intentional reception.

[45] While “the object necessarily takes the aspect of agent and end,” insofar as its corresponding power is passive or active, respectively, it is nevertheless included under the aspect of extrinsic formal causality, for it does not treat of the existence of things (as do the efficient and final causes) but of their essence: “This specification will therefore obtain in the line of formal causality, but this will not be intrinsic formal causality, for the objects are exterior to the acts and powers, and the acts, in their turn, are exterior to the powers. It remains that it is but a sort of causality, the extrinsic formal cause.” Stanislas Cantin, Précis de Psychologie Thomiste, (Québec: Les Presses Universitaires Laval, 1960) 35-6, “[Cependant, il importe de remarquer que si] l’objet se prend nécessairement du côté de l’agent et de la fin…. Cette specification se tiendra donc dans la ligne de la causalité formelle, mais ce ne sera pas de la causalité formelle intrinsèque, car les objets sont extérieurs aux actes et aux puissances, et les actes, à leur tour, sont extérieurs aux puissances. Il ne reste qu’une sorte de causalité, la causalité formelle extrinsèque.”]

[46] See St. Thomas, SLDA, (Leon.45/1.219-20:64-86).

[47] We can note, however, that the argument depends upon the fact that there are some objects (judgments, opinions, and understood simples) that cannot be accounted for by the sensitive powers; therefore, some other power is required.

[48] St. Thomas, SLDA, “. . . ostendit naturam intellectus possibilis.” (Leon.45/1.202:24-5).

[49] Ibid., “. . . quomodo reducatur in actum . . .” (Leon.45/1.201:25-6). These two parts correspond to the first chapter and first part of the second chapter, respectively, of SLDA III.

[50] Kurt Pritzl, “The Cognition of Indivisibles and the Argument of De Anima 3.4-8,” Proceedings of the American Catholic Philosophical Association 58 (1984): 141. St. Thomas agrees: see SLDA 216:81-5. The position of this reference requires that the first half of DA III.4 is meant, as Gauthier notes.

[51] St. Thomas, SLDA, “. . . primo proponit similitudinem intellectus ad sensum; secundo ex huiusmodi similitudine concludit naturam possibilis intellectus . . . tercio ostendit ex hiis que de intellectu probauerat differenciam inter intellectum et sensum . . .” (Leon.45/1.202:56-61).

[52] Ibid., “. . . sicut se habet sensitiuum ad sensibilia, similiter se habere intellectum ad intelligibilia, quia utrumque est in potencia ad suum obiectum et susceptiuum eius.” (Leon.45/1.202:87-90).

[53] Ibid., “. . . nam sentire, ut supra in II ditum est, non proprie pati est . . .” (Leon.45/1.202:76-7).

[54] Aristotle, DA, 429a18, “. . . quoniam omnia intelligit, inmixtum esse . . .” (Leon.45/1.201).

[55] St. Thomas, SLDA, “. . . non est aliquid corporeum uel commmixtum ex rebus corporalibus . . . neque habet organum corporale . . .” (Leon.45/1.203:94-6).

[56] St. Thomas, QDA, q.13, c., “. . . materialem immutationem annexam . . .” (Leon.24/1.118:309-10).

[57] Aristotle, DA, 429b3, “. . . cum intelligit aliquid ualde intelligibile.” (Leon.45/1.201). Generally, an example of this can be found whenever the mind rests in a cause, for causes are more intelligible than their effects, and the effects are better understood in them. An example is when Aristotle arrives at the definition of place in Physics IV (no pun intended). This understanding not only dispels the difficulties (confusions, a kind of lesser intelligible) concerning the definition of place, but it also allows local motion (less intelligible in itself experientially) to be understood scientifically. Whence, “greatly intelligible” must be taken to mean what is better known in itself, not what is better known to us. The intelligibles notior naturae are bright lights that shed light on and intensify the lesser lights that guide our first, obvious experiences.

[58] St. Thomas, SLDA, “Ne ergo aliquis crederet quod in eodem gradu inpassibilitatis esset sensus et intellectus . . .” (Leon.45/1.205:243-4).

[59] Ibid., “. . . cum organo careat, under nec per se nec per accidens passibilis est.” (Leon.45/1.205:250-1).

[60] Aristotle, Physics, translated R. Glen Coughlin (South Bend: St. Augustine’s Press, 2005) 190.

[61] See St. Thomas, De Unitate Intellectus, “Therefore the limit of the consideration of the physicist concerning forms is in forms which are in matter in a certain way, and in another way not in matter; for such forms are on the border of the separate and material forms.” [“Terminus ergo considerationis phisici de formis est in formis que sunt in materia quodammodo, et alio modo non in materia; iste enim forme sunt in confinio formarum separatarum et materialium.”] (Leon.43.297:518-522).

[62] St. Thomas, QDA, q.1, “. . . in confinio corporalium et separatarum substantiarum [constituta].” (Leon.24/1.10.340-1). Compare De Unitate Intellectus, fn.61 above.

[63] Themistius, On Aristotle’s On the Soul, 15.

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