A heads up for those interested in critiquing my understanding of evolution.

- Prolegomena, a general thought:
Where philosophers disagree most is about the principles of things, and the order in which to apply principles when giving a causal explanation of common experience. An example of this is the order between things known and concepts of things known: St. Thomas Aquinas and Immanuel Kant give diametrically opposed accounts of the order between these ‘things’. Another example, it seems, is how to give a principled account of the natural law. A list of goods, specifically human goods, requires a principle by which to judge the fittingness of the list.


- Notes about first readings into the new natural law theory (NNLT):
1) Tollefsen states that the thesis of the NNLT is “that the foundation of practical reason is in a foundational practical recognition of certain basic goods, and that no inference from theoretical truths concerning human nature is necessary or possible.” (1) This is not a view to be taken lightly: “inference from theoretical truths” is the basis for ethical thought. For example, Aristotelian psychology provides a “launching point” or occasio to ethical considerations because it gives an account of the parts of the human soul and the hierarchy among its powers (see St. Thomas, Sententia Libri de Anima, I, l.1). It seems that Hume’s guillotine is not something to be avoided, but refuted. The ‘ought’ is derived from ‘is’ when the ‘is’ is descriptive of the finality that shapes the very definition, ratio, or raison d’etre of a being, in this case a human being.

2) Rowland makes several interesting comments. (2) First, as an introduction to his attempt to establish a “theological natural law” he states that in an attempt to dialog with non-believers, it has been conceived possible “to sever [natural law] from its theological roots.” (3) It is true that the context of St. Thomas’s treatise on law makes a separation from the mode of the science of theology a risky undertaking. However, (provided the distinction between revealed and natural theology), an account of natural law can be given by a science strictly philosophical in order and mode, which conclusions and arguments can be reaffirmed by a higher science (theology), which reaffirmation is no vain attempt because of the diverse ways in which the two sciences conceive of their scientific objects and the natural law as a part of that object.
Second, Rowland indicates the heart of the issue:

Cardinal Ratzinger . . . described natural law as a “blunt instrument” in dialogues with secular society. This was not because he personally rejects belief in natural law, but because he believes that it presupposes a concept of nature in which nature and reason overlap, a view which he further claims was “capsized” with the arrival of the theory of evolution. Without a foundational belief in a divinely created cosmos, the doctrine falls on incredulous ears. It lacks persuasive force. Post-moderns will never buy it because they have rejected a notion of nature that includes stable essences, and Liberals will never buy it because individual autonomy occupies such a high place in their hierarchy of goods that it trumps any appeal to a notion of there being one single vision of a “good life.” . . . Reason has been truncated to finding efficient ways of achieving ends and nature is now subject to scientific manipulation so neither reason nor nature is a strong foundation upon which to build a bridge to the contemporary Liberal tradition. (4)

This is the basis upon which all discussion of “natural law” hinges. First, there is the understanding of “nature” and its correlative, “reason.” These are the touchstones upon which any account of a natural law for man (the being rational by nature) must be based. Furthermore, to obtain the full ratio of law, this natural law must be “theologically” derived in the sense that it is placed within the context of a (divinely) rational legislator, i.e. a cosmos (cosmein: order, marshalling troops) with a super-cosmic origin and source of direction or finality. This requires neither revelation strictly speaking nor does it invalidate the conclusions of natural ethics, which would only imperfectly attain to the full ratio of law.) Third, this cosmic order is eternal, but not necessarily in an immutable Stoic sense, and hence can give an account which utilizes evolution as instrumental principles (satisfying the concerns of the post-modern) which instrumentality requires direction by a non-instrumental source. This introduces a hierarchy of goods (for a hierarchy or subordination of instrumental operations to primary causes by nature must be an order of goods insofar as it imports final causality) within a natural order (satisfying the concerns of the liberal). Natural science in a classical sense (Aristotelian/Thomistic) can adequately ground an account which serves as a “launching point” to ethics and natural law (5). Reason is not and cannot be truncated by science.

+Endnotes+

(1) Christopher Tollefsen, “The New Natural Law Theory,” Lyceum 10.1 (2008): 1. Tollefsen refers to Germain Grisez’s foundational essay: “The First Principle of Practical Reason: A Commentary on the Summa Theologiae, 1-2 Question 94, Article 2,” New Natural Law Forum 10 (1965): 168-201.
(2) Tracey Rowland, “Natural Law: From Neo-Thomism to Nuptial Mysticism,” Communio 35.3 (2008): 374-396.
(3) Rowland, “Natural Law,” 374.
(4) Rowland, “Natural Law,” 374-75.
(5) See Charles de Koninck, Le Cosme, and Richard Hassing, “Darwinian Natural Right?” Interpretation 27.2 (2000): 129-60. (http://philosophy.cua.edu/faculty/rfh/)

This is the revised draft of the preface to my thesis. I might not include it at all, but it was helpful pre-writing. Please let me know what you think, including whether or not I should include this, or something like this. Thank you!


The following thesis is admittedly much influenced by the thought of Aristotle. While Aristotle's influence can be seen in many ways in this thesis rather overtly, nevertheless there is an underlying principle which is at work that cannot (and should not, to my mind) be addressed during the course of the thesis properly speaking. Most generally this principle is that there is an order to the various philosophical disciplines. While there is much to be said about this order, most specifically the order with which I am concerned is the Philosophy of Nature precedes Metaphysics, or first philosophy, in the order of learning.
As contemporary commentator Glen Coughlin claims, “If there is to be any understanding of metaphysics as Aristotle conceived it, or even of Aristotle's conception of metaphysics, it will have to be preceded by a careful study of natural philosophy...” This is for the simple truth that immaterial being does not evidently exist and according to Aristotle “If there were no substances other than those formed by nature, physics (natural philosophy) would be the first science.” Further, it is through the study of mobile being that we arrive at our understanding of immaterial being, as in Aristotle's De Anima, that presupposes much of the Physics. Also at the end of the Physics Aristotle concludes to the first mover and states “Therefore it is apparent that it is indivisible and partless and a thing having no magnitude.” Our knowledge of immaterial being is largely knowledge by negation. The Physics, therefore, concludes to immaterial being, and can say no more about it since its object if mobile being. It is from here that one is must begin first philosophy, or metaphysics.
From these considerations it is clear that in the order of learning, Natural Philosophy must precede Metaphysics. This is simply how to move from the more known to the less known. This is a formative principle behind this thesis.
Throughout this thesis I will be focused on treating the methodology of Natural Philosophy as a natural philosopher, not a metaphysician. The principles I intend to resolve to in order to make my argument will belong to the disciplines of Logic and Natural Philosophy. This approach has both weaknesses and advantages, yet it is important to maintain.
The possible weaknesses that can be encountered by such an approach is that there may be metaphysical objections or problems to some arguments, that will not be sufficiently dealt with. This does not mean that the arguments should lack their proper certainty, or not conclude properly, but rather that there may be what Aristotle terms, ἀπορία, that cannot be resolved, which nevertheless does not disprove what was said.
The great advantage of this approach is that it will assure a narrow and focused discussion that will not be weighed down by digression or confusing side arguments that do not immediately pertani to the task at hand. This will mean that this thesis will likely end with more questions than it began with, but as long as the questions with which I end are different from the ones I began with, I shall consider my work successful.

Below is a first draft of the preface to my thesis. I would appreciate your thoughts and input on it. At this point I feel like it is rather clumsy, and lacks the proper rhetorical flair. Please let me know if anything about it sounds to overbearing, unnecessary, etc.

In the many conversations that I have had concerning this paper I have encountered certain questions and difficulties that this paper presents, and yet are not addressed within the scope of the paper. The questions of which I speak, pertain to the foundations on which this paper, and my own ideas proceed. This foundation can be described (if you will pardon the cliché) as my “world-view,” or as it has elsewhere more aptly been described, my intellectual custom.
By referring to this intellectual custom I do not mean to suggest that I have some wholly unique perspective, nor do I propose to say that different intellectual customs are wholly alienated from one another such that communication is impossible between them (hence I am writing this preface). Rather, I believe that while my perspective, in one sense, is necessarily unique since I am unique. It is likewise necessarily part of a broader community in which I have been formed, raised, and influenced, since it is impossible for us to exist, separated from any outside influence. This broader community is that wherein the intellectual custom I share in exists. (What Aristotle says about arguments)
Judging, therefore, from the sorts of questions I have encountered regarding this paper, I assume that many of those with whom I have conversed come from a somewhat different intellectual custom. Perhaps this means that I am part of some sort of minority, or that I have merely encountered a peculiar sample. Whatever the case may be, I will endeavour to use this preface as an occasion to sketch, as it were, a backdrop for the following paper. This will not be so much argumentative as descriptive, and all this is done with a view to obviating the objections that would not be so much against the thesis as against the approach that is being taken to this thesis.
I want to acknowledge further, that some intellectual custom may be superior to another and that there are somethings that belong to this intellectual custom about which arguments can be made, and about which I can be in error. I wish merely to establish clearly the pertain aspects of the foundation from whence I am proceeding so that questions and objections might be distinguished accordingly.
Chief among my principles is the conviction that Philosophy is about things and attempts to speak of things in so far as they are universal and unchanging. It follows, therefore, that I am more interested in ideas than in those that held the ideas. In this way, the title of this thesis may be somewhat misleading. I am not actually concerned with the thoughts that went through Aristotle or Newton's minds except accidentally. I trust the interpretations of the texts will not be too far from what they think, but nevertheless I must confess that it is possible they would object to the way I portray their thoughts. Nevertheless, this is not a court where persons are being tried, it is a philosophical treatise where ideas are considered, and these ideas are held to be better or worse to the extent they correspond to the way things are. A further consequence that will be noted is how I blithely and liberally use the commentaries of St. Thomas Aquinas to understand Aristotle. I do this because St. Thomas seems to make the best sense of the texts of Aristotle. By makes “the best sense” I mean that he reads them in such a way as they make sense of things and make sense to me. Using the names of Aristotle and Newton, therefore, should be taken as more of a short-hand way of referring to their works.
This chief principle, as I have designated it, presupposes another: that things are intelligible. By many this claim is challenged. If it is not questioned that things can be known at all, there is great debate about to what extent things can be known. As important and interesting as these questions are, they have to be put aside. Unless I am to begin every work with an epistemological treatise, I must take it as given that I am able to know things. (Though how and to what extent merits discussion.)
Another frequent concern that has been brought to my attention is that in comparing Aristotle and Newton I am holding one as better than the other, as if I were pitting them against one another in some intellectual boxing match and that I grant victory to the one I favor. I will here give a glimpse of the following thesis: I will use terms such as “prior” and “more proper.” These are not intended to mean “better,” simply speaking. They will mean better in a certain respect. Prior means that it is better for this one to proceed the other. More proper means that it better suited to this end than the other, and this will be largely due to the other having a different end altogether. In essence, therefore, by saying prior and more proper, I am saying let the first is before that which follows, and that each is better suited to its proper rather than the end of the other.
Having laid down these prefatory remarks, I hope that I have sufficiently established the thought behind my thesis. That philosophy is about things, and that things are intelligible form the cornerstone of my philosophical approach. My clarifications about what it means to be prior and proper are to make clear the rhetorical approach that this thesis intends.

Aristotle gives the proper order of investigation in 415a 15-23: object, operation, power, soul. But in considering the intellect, he first considers the power (429a 10 – 430a 26), then its operation (430a 27 – 431a 4). Again, in considering the possible intellect, he first considers the power of the possible intellect (429a 10 – 429b 9), then its object (429b 10-23). Any thoughts?

An Inquiry into the Question of Inertia

You will notice that there is much in this article that was taken from my previous post on the definition of motion. I decided to re-direct my ideas and focus on method, more than the actual question of motion and inertia.

St. Thomas Aquinas makes a bold claim concerning Aristotle’s definition of motion saying, “And therefore it is wholly impossible to otherwise define motion through what is prior and more known, but as the philosopher has here defined it.”i Such a claim, from such a mind, warrants a careful look as to the reasons behind a claim of this force. The significance of this inquiry is great. Aristotle's definition of motion is challenged by a fundamental principle of modern day physics, inertia. How to reconcile these ideas or change them is, therefore, an important question for those who do not wish to simply abandon Aristotle and St. Thomas.
We are left then with the quandary of what to do. Modern day thought on the whole encourages us to scorn ancient thought and embrace the current understanding of things. After all, modern science has taken us to the moon. Even so, there is a puzzle. When Aquinas made his bold claim, was he merely stuck in the world of own limited science? Did he make this claim based upon the poor and limited scientific data available at the time? It is interesting to note, that neither he nor Aristotle bring up the importance of accumulating more “data” at all in their explanations. Probably most striking to our modern sensibilities is that neither of them even mentions the idea of force or anything like it in their accounts.
The differences between the present day approach to the physical world and in particular to motion, and the ancient and medieval approach explains many of these difficulties. The modern day physicist proceeds according to what is commonly known as the scientific method. I here define it as a systematic method of inquiry proceeding according to hypothesis and experiment. Consequently, modern scientists establish various models to explain what they experience and then abandon them for another, better model when one should come along.
Aristotle and St. Thomas were engaged in a much different enterprise as can be clearly seen in their works. The classical approach was one that sought, first of all knowledge, or as St. Thomas would have said scientia. This cognate is obviously related to our modern day word for science, but its meaning is much different. Aristotle defines such knowledge in his Posterior Analytics,
“We think we know each [thing] without qualification, but not in the sophistical manner with respect to an attribute, when we think that we know the cause through which the thing exists as being the cause of that thing and that the thing cannot be other than what it is.”ii
As he will later show in his De Anima this knowledge comes from the abstraction of the forms of things by the agent intellect, so that the mind truly knows things.iii
As is clear, the two approaches to understanding the physical world are vastly different. While the differences between these two approaches are such that it seems impossible to say whether one is better than the other, it does seem that we may argue for one being prior to the other. This brings us to the purpose of this paper. While it would be a great task to once and for all settle the question about inertia and the classical definition of motion, at least we can here argue for where we ought to begin looking. My thesis is two-fold: Aristotle's definition of motion is prior to the account of inertia in the order of knowing in that it is self-evident. Consequently, any account of inertia must be able to keep this definition if it is to be taken as true.
To proceed I will first argue that the only valid way to proceed in any inquiry is as Aristotle states in the beginning of the Physics “The natural path is to go from things which are more known and certain towards us toward things which are more certain and more knowable by nature.”iv I will then address some preliminary concerns to the definition of motion. After this, I will examine Aristotle's definition of motion and how he argues that it is true showing that it is in fact self-evident, given Aristotle’s principles of nature. This being shown, I will conclude by claiming that this definition must be held if one is to investigate the physical world, in particular in examining the principle of inertia.

Beginning
In every inquiry in which there are principles or causes or elements, understanding and science occur from knowing these. For we think we know each thing when we know the first causes and first principles and have reached the elements. It is clear, then, that in natural science as well one must try to determine first what concerns the principles.v

So Aristotle opens the physics and directs us to examine the principles of natural philosophy. It is then that he enunciates the principle which will be our primary concern in this essay, “The natural path is to go from the things which are more known and certain to us toward things which are more certain and more knowable by nature.” There are some questions that the formulation of this principle brings up. In particular, the distinction between what is more known to us and what is more known by nature, for this is the principle by which Aristotle justifies this mode of proceeding. In this section I will argue that there is no other way to proceed with certainty and scientia except by this path that Aristotle lays forth. While such an inquiry belongs properly to epistemology, we will be able to touch on this matter briefly.
It is sufficient here to see that there are some things that we are able to see more immediately than others. For instance, I know that the whole is greater than the part, or that equals added to equals are equal. Such axioms are certain and clear to our minds. Further claims, such as the interior angles of a triangle equal two right angles, are true, but certainly cannot be grasped with the immediacy of the afore mentioned axioms. In fact, following Euclid's Elements there are various definitions, axioms and postulates, let alone propositions that I must comprehend before I can see that the interior angles of a triangle are equal to two right angles.vi
The movement in mathematics, however, is simpler than that of Aristotle’s Physics. Aristotle, since he is dealing with physical and therefore sensible realities, must move from his experience of things to the principles, and then from principles to demonstrations. The greater part of the Physics is dedicated to the discussion of principles. It is not until the sixth book (of eight) that Aristotle even begins to do demonstrations, properly so called. Therefore we see that the philosopher of nature must spend time examining his experience, moving from the more known to the less known.
He gives three analogies by which to understand this method. The first: “For the whole is more known according to sensation, and the universal is a certain whole. For the universal embraces many things within it as parts.”vii This analogy allows us to consider our experience in a way like the universal and particular. In our experience of things, say a tree, we realize that this is a kind of whole that is composed of other things which are themselves able to be known. We must be attentive to our experience to see what things might be contained therein.
This idea is further elaborated when Aristotle gives the second analogy, “In a way the same thing happens in the relation of a name to its account. For the name signifies indistinctly some whole, as circle, but the definition of this divides into the single parts.”viii Therefore, given that sensible whole, with its various parts, we see that the whole is grasped by the intellect as something indistinct. To better understand this whole we name and define the parts which are less obvious to us, but simpler and clear ideas in themselves. So in the case of the circle, we see that its principles are the point and the line, and these are more simply intelligible in themselves, but we first know the circle.
Aristotle then gives his final analogy, “And children at first call all men “fathers” and all women “mothers” but later they distinguish each of them.”ix Children take time to distinguish between adult males and adult males with offspring. So also we need time to distinguish those things that look the same to us, so that we must see their differences. As we are defining and seeing parts we will come to distinguish some things that were confused before.
Using these three examples Aristotle establishes that the confused whole that we first grasp, is in fact confused. It is what we know better, but it is not as intelligible on its own as the parts. We must grasp the parts and define and distinguish them in order to understand our experience. We must wade through the various sensations that we have received, and Aristotle gives us an ordered means by which to do so. Start with what we know, and then move forward. To abandon what we knew at first leaves us lost and adrift in the wild ocean of natural philosophy. We see therefore, that the “natural path” is the only path on which we can proceed with certainty. Therefore, it is the only path by which we can proceed scientifically.

Preliminary Considerations
It is well that we should first make a note regarding the most jarring part of my claim about motion that it is self-evident. Something can be self-evident in many ways. There are principles which the mind grasps immediately, and as obvious, such as “the whole is greater than the part.” There are also principles which St. Thomas calls “self-evident to the wise.”x What is characteristic of such principles is that they are not obvious to everyone. However, both kinds share in common that the mind immediately grasps them. What this means is that there is no middle term showing that they are the case, but rather, through sufficient reflection on experience one sees that it is true. This is to say, there is no proper demonstration of the definition of motion.xi (ref.)
It is nonetheless true that Aristotle's definition of motion, “the actuality of what exists in potency, as such,”xii provides challenges. Prima facie, this definition seems incomprehensible. This is because he is defining motion by what is prior to motion. While it seems reasonable enough that we must define motion in terms of something prior to motion, it challenges us, because there does not seem to be motion in the definition. This difficulty can be surmounted, only if we are able to understand how act and potency are prior to motion.
One final note about Aristotle's definition of motion before we proceed: he is not only defining locomotion, that is, motion from place to place. He certainly sees this as the paradigm of motion and will even say that it is at the base of all other kinds of motion, but he will consider growth and diminution, alteration, and locomotion as kinds of motion. Therefore he will speak of motion in very general terms, which is at once an excellence of his account, and a challenge to we who would understand him.
There are certain principles Aristotle assumes that his readers have at this point grasped and understood. I will not here argue to these principles, but take them as given. First of all we should know that there is such a thing as change and what a change is. If one denies that there is change then natural philosophy can have nothing more to say to him. Such an objection is for metaphysics. According to Aristotle, we must understand change to be, generally speaking, the loss or reception of a substantial or accidental form by some substance. Likewise, we must accept that there is such a thing as a nature. Again, the denial of this brings us to metaphysics. Aristotle defines nature as “a certain principle and cause of moving and of resting in that which it is, primarily, in virtue of itself, and not accidentally.”xiii
Aristotle comes to the principles of nature and change and calls these matter, form and privation. These again are taken as given. It is worthwhile here to point out though that these are indeed principles. There is no demonstration that these are true; they are manifested by reflections upon experience. Finally, Aristotle expects us to have some idea of potency and act. While these are likewise principles and therefore indemonstrable, we will pause briefly to see how Aristotle is able to come to the ideas of potency and act.
Aristotle first mentions the ideas of actuality and potentiality as a proper consideration of natural philosophy in Book II chapter 1. Here we are introduced first to potentiality when he says, “We would not yet claim, in the former case, that the bed has anything according to art if it is only a bed potentially and had not yet the species of a bed.”xiv He is here setting up an analogy between nature and art. The timber is potentially a bed just as matter is potentially flesh. This analogy is very similar to the one he uses to show that there is prime matter. There he argues that as the timber is to the bed, so is there some underlying principle that stands to formxv. He thus moves from matter to see that there is potency, a more general idea that something can be something, but is not. The idea of actuality immediately follows as a correlative. Therefore, when the timber is, the bed, it is no longer the bed potentially but actually.

Definition of Motion
When beginning his inquiry into the definition of motion Aristotle lays out those things that are concomitant to motion.xvi This should make us realize that a complete understanding of what motion is, will be impossible until we have considered the continuous, the infinite, place, void, and time. Having given us this context Aristotle makes a division between potency and act. “There is, then, something which is only in actuality and something in potency and actuality.”xvii This is the first of three divisions that he makes in his search for the definition of motion. As Glen Coughlin points out in his appendix on the definition of motion, it is important to note what is meant by potential.xviii He is dividing act from potency and for this division to be helpful, and then there must be things that stand in opposition to one another. For instance, it does not aid our inquiry to say that I have the potency to stand because I am standing. Therefore, we must understand potency together with privation of some act. However, we cannot confuse potency and privation.
Aristotle proceeds to explain the basis for relations as excess and defect, action and passion, the mover and the mobile. He leaves this aside at this time, but he will return to this consideration when discussing the relation between the mover and the moved. We shall also take this up below.
The second distinction is made when Aristotle states, “motion is not beyond things.”xix That is to say, that it is not beyond any of the categories. The final distinction points out that in every genus there is a being and privation of that being.
We see from the first division that motion must belong to what can be in potency and act. This is clear if we consider that motion is a kind of change, which is obvious from experience. What does not have potency (and this is potency understood with privation, as was said) is unable to change, for there is, as it were, nowhere for it to go. Therefore, motion must pertain to what can be in potency and act.
The second distinction, that motion belongs to the categories, must be understood in two ways. First, that motion cannot be some super genus since “one can grasp nothing common.”xx Second, we must understand that motion is not some eleventh category since there is “nothing beyond the things named.”xxi We may therefore conclude from this that motion is going to be understood in the context of a genus.
The third distinction concerning the being and privation in each genus indicates where to look for motion in a genus. That is, it is going to be somewhere between the being and privation, the white and the black or the perfect and imperfect, etc. It must be clear that when Aristotle says that “the species of motion and change are as many as are those of being,”xxii it does not mean that there is motion in every genus, as he will later deny, but he is claiming that as many categories as admit of motion, so many will the species of motion be. There will not be one kind of motion for multiple categories.
From the above we may conclude that motion belongs to those things that are in act and potency in some genus, according to the mode of that genus. We must take this together with our common experience of motion. We know motion as that which is between its two ends, “that from which” and “that towards which.” For we see the apple moving from green to red, or the child growing to his full height when a man, or the cup being here, and then being there. Such is out experience of motion.
What we know about motion at this point is its ends. For I know that the mobile is here or there, but when it is here or there I do not say that it is in motion. Therefore, since we know the ends of motion and we must always proceed from what is more known to the less known, then we must define motion in terms of its ends. For the sake of generality we will names these ends, “that from which” and “that towards which”
The end “from which” is what the mobile posses now, before it has gone somewhere. It is the end that is held in act. The end towards which is what is held in potency, the mobile is not there. We also see that there are any number of points in between these two at which the mobile could be said to be if its motion did not continue on. The mobile has no intrinsic order away or towards either end if it comes to rest at one of these points. If I get up and walk to the doorway and stop, I do not belong to either room more than the other. It is only in motion that I have an order towards or away from some point.xxiii
From these considerations we see that motion is a kind of potency, since it does not possess its end. We see also that there is a kind of actuality to motion. The points at which the motion could stop are closer to the end, so long as we take the order provided by the motion, than the point from which the motion began. Therefore, as long as it is moving it is becoming the end towards which.
Now, the end that towards which is what the mobile holds in potency, before and during the motion. Once the mobile holds the end towards which in act the motion is completed. However, we may still define this in terms of the end from which as the end from which. In order to do this in the language of act and potency, we say that mobile at the end “towards which” is the actuality of the potency. Or in a parallel formulation to Aristotle's definition, it is the actuality of what existed in potency.
So far, we are still speaking of the ends and not of what lies between them. We therefore want to understand the end “towards which” as it exists in potency, not as it existed. Therefore we must understand that potency insofar as it is still in potency. This is our definition: the actuality of what exists in potency, as it is in potency. As Aristotle phrases it, “the actuality of what exists in potency, as such, is motion.”
We see therefore, that Aristotle proceeds by starting with what is prior and more known, namely potency and act. We then consider what is “in between” these and this is what gives us motion. The argument works by the mode of manifestation. If something is in potency it is not moving, and if it is in act it is done moving, we therefore must look to what is between. There is however, no cause of this definition given. We do not see why motion is this way; we see only that it must be this way. This is what is proper to a principle, that there is no cause of it that the mind can grasp; we see only that it is.
Inertia
Sir Isaac Newton first introduced the world to the idea of inertia in his treatise Natural Philosophy’s Mathematical Principles. Right away we see that his conception of natural philosophy is different that Aristotle’s, given that he is searching for its mathematical principles. For Aristotle, mathematics and philosophy of nature were two very different things. We will discuss more of these differences below. In this section I will argue that Newton’s approach to natural philosophy is positivist in nature and that he proceeds as a mathematician.
Newton introduces us to the idea of inertia in the third definition. “Innate force of matter is the power of resisting, by which and body whatever, as much as is in it, perseveres in its state either of resting or of moving uniformly in a directed line.”xxiv By innate force of matter I am understanding inertia. This understanding seems to hold weight given the first sentence of the explanation of his definition, “This force is always proportional to its body, and does not differ in anything from the inactivity {inertia} of the mass except in the mode of conceiving it.”xxv At this point, there is not much to say regarding his method, only that he has proposed definitions of things that may or may not exist and that these definitions bring up questions them.
After his definitions Newton expounds the philosophical framework in which theses definitions are to be understood. In his Scholium Newton explains his understanding of “Time, space, place, and motion.”xxvi There is much that can be questioned in his accounts but to do so would divert us from our purpose. We will here only note what he does.
After his Scholium Newton introduces us to his “axioms or laws of motion.”xxvii The first law is that which interests us, as it is the law of inertia. “Every body perseveres in its state of resting or moving uniformly in a directed line, except insofar as it is compelled to change its state by impressed forces.” immediately there seem to be difficulties. First of all questions arise such as “What does it mean for a body to be in a state of motion?” and “What is force?” These questions should then lead us to wonder what Newton could mean by calling these axioms. This law seems to be a far cry from “The whole is greater than its parts.”
We see that this proceeds very much like Euclid’s Elements. Euclid first lays down his definitions postulates and common notions and then proceeds. There is no discussion of these principles. This seems to be more acceptable since most of these seem fairly straightforward.However, when Newton begins a study of natural philosophy thus, it seems to beg many questions that are not here addressed. What Newton has effectively done is proposed a model by which to understand the phenomena. The certainty that we have in his explanation comes from seeing how effectively it explains the phenomena. This is what has become known as positivism.
In his highly influential work The Structure of Scientific Revolutions, Thomas Kuhn undertakes to describe the process of scientific revolutions and points out that they are essentially changes of what he calls “paradigms”xxviii That is, someone posits another model by which to understand the phenomena and the majority take hold of it. This is essentially what Newton has done. He has put forth a way of understanding the world. This includes the definitions and the Scholium which we mentioned earlier. This world view and the laws by which he describes it are far from axiomatic. This is not to say that they are false, merely that are not immediately grasped by the mind, and that a great amount of discussion should be gone through before accepting these ideas as true. We must work through our experience to see these as principles.
It seems right that Einstein has improved on Newton and his theories have taken precedence.xxix We will not, however, go on to discuss Einstein, because it is beyond our purpose. It is of concern here to put forth the way in which modern empirical science ought to proceed, not to describe how it has proceeded. What is more, I am not here going to criticize the principle of inertia, but only provide certain requirements which adherents to this principle must meet. This is the subject of the final section.
Conclusion
Newton's method fails to proceed according to the natural path as laid down by Aristotle. The language he uses seems to indicate that he is, but on a closer examination, we see that there are significant gaps. The difficulties with Newton's method are that he treats physical objects mathematically and that he does not proceed from what is more known to us, to what is more known by nature. What follows is that his method is not scientific in the classical sense.
The argument about treating physical objects mathematically has hitherto only been implied in this paper. A further discussion of this question would belong to a different study that would examine the various degrees of abstraction, and to what extent certainty can be had in these various degrees and whether there can be any overlap. Since this would take us beyond our primary purpose, we will leave this discussion aside and attend to the second difficulty raised, namely, Newton's invalid mode of proceeding.
Given that Newton is discussing natural philosophy he should proceed in the manner the Aristotle did, moving from the confused whole to principles, and from principles to demonstrations. As we saw above, Newton instead posits his principles, much like the mathematician. The difficulty here is that these principles are not axiomatic as we saw. There needs to be arguments to manifest that these are in fact principles.
There are two ways to go from here, one is to supply the missing dialectic of Newton’s Principia, and try to manifest his principles, or to say that Newton's project is wholly other than that of Aristotle's and that we ought not to hold him to the same standards. It is a different method. Given that Einstein does improve on Newton and effectively throw out Newton's world view, I will take the harder case, that Newton is undertaking a wholly different project.
This position is lent credence by examining the very title of the work, where it speaks of mathematical principles. Throughout his work Newton will express phenomena in a mathematical way. This seems to be vastly different than the way Aristotle speaks of motion and comes to his definition. If this is the case, as it seems that it is, then the question resolves back to the first difficulty raised regarding Newton's method, namely treating physical objects mathematically.
What can be said here is that this may in fact be a valid means of proceeding. The modern scientific hypothetical-deductive method has seemingly accomplished much and we should be loath to abandon it simply because it does not seem to conform so precisely to Aristotle's “natural path.” However, despite the great ability of this method to accomplish things, we must also be wary not to throw out the method of Aristotle. To use contemporary terminology, Aristotle is doing philosophy and Newton is doing science. Aristotle's method provides certainty, while Newton's does not seem to do so. If then we are to proceed effectively and with knowledge, then any account of inertia and inertial motion should be informed by what is held with certainty by following Aristotle. Aristotle's definition of motion is therefore prior in the order of knowing, as it is held with certainty and to further understand inertia and the world about us, we must hold on to what we know and proceed to into the unknown.

NOTES
i Thomas Aquinas In Pysicam bk. 3, lectio 2
ii Aristotle, Posterior Analytics, 1.2.71b10-2
iii Aristotle, De Anima, 2.5.
iv Aristotle Physics 1.1.184a17-19
v Ibid., 184a9-16
vi Euclid, Elements bk.1
vii Aristotle, Physics 1.1.184a25-27
viii Ibid., 184b9-11
ix Ibid., 184b12-13
x Thomas Aquinas, Summa Theologiae, I, Q.1, a1
xi Thomas Aquinas, In Physicam, bk.III, lectio 2
xii Aristotle Physics 3.1.201a11-12
xiii Ibid., 2.1.192b21-23
xiv Ibid., 193a34-36
xv Ibid., 1.7.191a9-11
xvi Ibid., 3.1.200b16-26
xvii Ibid., 200b26-27
xviii Aristotle. Physics Or On Natural Hearing, ed. and trans. Glen Coughlin, William of Moerbeke Translation Series, (South Bend IN :St. Augustine’s Press, 2005), App. 6, 246.
xix Aristotle Physics 3.1.200b33
xx Ibid., 200b34-35
xxi Ibid., 201a3
xxii Ibid., 201a9
xxiii Aristotle. Physics Or On Natural Hearing, ed. and trans. Glen Coughlin, William of Moerbeke Translation Series, (South Bend IN :St. Augustine’s Press, 2005), App. 6, 248.
xxiv Isaac Newton Natural Philosophy’s Mathematical Principles, ed. Chris Decaen, trans Ronald Richard , (Thomas Aquinas College, 1996) 3.
xxv Ibid.
xxvi Ibid., 6.
xxvii Ibid., 11.
xxiii Thomas Kuhn, The Structure of Scientific Revolutions 3rd ed., 10
xxix Antonio Moreno, “The Law of Inertia and the Principle Quidquid Movetur ab Alio Movetur,” Thomist 38 (1974) 313-316.

In the following essay I briefly explicate the definition of motion as given by Aristotle. This is an excerpt from a larger work that has been modified to stand on its own. This will be the first in a series of articles that is concerned with motion. In particular we will discuss inertia and its validity as a principle, especially in light of the definition of motion and the principle, "omnia quod movetur ab alio movetur"

Defining motion poses a daunting task for any thinker. This is for two reasons: First, motion is not very much of a being. As will be shown below, it has only a kind of potential, or imperfect being and this is the the reason that Aristotle notes that “it is difficult to grasp what motion is.”i . Second, it is very much a principle of our coming to understand nature, and as such, it is one of those things that is more known by nature, and less known to us. On account of these difficulties, definitions tend to fail in one of two ways. They end up being circular, such as Descartes' and Newton ii after him, or they end up neglecting the continuity of motion as notably done by Bertrand Russell.iii Aristotle's definition is the only definition that obviate these difficulties and comes to the truth. As St. Thomas says, “It is altogether impossible to define motion through what is prior and more known accept as the philosopher defines it here.”*
It is nonetheless true that Aristotle's definition of motion, “the actuality of what exists in potency, as such,”iv provides its own challenges. Prima facie, this definition seems incomprehensible. Indeed, Descartes remarked famously about this passage, “Who understands theses words?”v In addition to the difficulties that we are confronted with above, Aristotle's definition is hard because he is defining motion by what is prior to motion. While it seems reasonable enough that we must define motion in terms of something prior to motion, it challenges us, because there does not seem to be motion in the definition. This difficulty can be surmounted, only if we are able to understand how act and potency are prior to motion.
One final note about Aristotle's definition of motion before we proceed: he is not only defining locomotion, that is, motion from place to place. He certainly sees this as the paradigm of motion and will even say that it is at the base of all other kinds of motion, but he will consider growth and diminution, alteration, and locomotion as kinds of motion. Therefore he will speak of motion in very general terms, which is at once an excellence of his account, and a challenge to we who would understand him.
When beginning his inquiry into the definition of motion Aristotle lays out those things that “are concomitant to motion.”vi This should make us realize that a complete understanding of what motion is, will be impossible until we have considered the continuous, the infinite, place, void, and time.vii Having given us this context Aristotle makes a division between potency and act. “There is, then, something which is only in actuality and something in potency and actuality.”viii This is the first of three divisions that he makes in his search for the definition of motion. As Glen Coughlin points out in his appendix on the definition of motion, it is important to note what is meant by potential.ix He is dividing act from potency and for this division to be helpful, then there must be things that stand in opposition to one another. For instance, it does not aid our inquiry to say that I have the potency to stand because I am standing.x Therefore, we must understand potency together with privation.
Aristotle proceeds to explain the basis for relations as excess and defect, action and passion, the mover and the mobile.xi He leaves this aside at this time, but he will return to this consideration when discussing the relation between the mover and the moved. We shall also take this up below.
The second division is made when Aristotle states, “motion is not beyond things.”xii That is to say, that it is not beyond any of the categories. The final distinction points out that in every genus there is a being and privation of that being.xiii
We see from the first division that motion must belong to what can be in potency and act. This is clear if we consider that motion is a kind of change, which is obvious from experience. What does not have potency (and this is potency in the sense of privation, as was said) is unable to change, for there is, as it were, no where for it to go. Therefore, motion must pertain to what can be in potency and act.
The second distinction, that motion belongs to the categories must be understood in two ways. First, that motion cannot be some super genus since “one can grasp nothing common.”xiv Second, we must understand that motion is not some eleventh category since there is “nothing beyond the things named.”xv We may therefore conclude from this that motion is going to be understood in the context of a genus.
The third distinction concerning the being and privation in each genus, indicates where to look for motion in a genus. That is, it is going to be somewhere between the being and privation, the white and the black or the perfect and imperfect, etc. It must be clear that when Aristotle says that “the species of motion and change are as many as are those of being,” it does not mean that there is motion in every genus, as he will later deny, but he is claiming that as many categories as admit of motion, so many will the species of motion be. There will not be one kind of motion for multiple categories.
From the above we may conclude that motion belongs to those things that are in act and potency in some genus, according to the mode of that genus. We must take this together with our common experience of motion. We know motion as that which is between its two ends, “that from which” and “that towards which.” For we see the apple moving from green to red, or the child growing to his full height when a man, or the cup being here, and then being there. Such is out experience of motion.
It is worthwhile to point out that to a large extent our current question focuses on this claim precisely, that is, must motion have an end. For now, it is important to see what we experience simply of motion, such as in the examples given. Moreover, even inertial motion must be defined in terms of non-motion. Finally, inertial motion is certainly less known than the above examples and is consequently not profitable to examine at this point. We must proceed from what is more known to what is less known.xvi Therefore we will begin here and see if we need to clarify our definition later.
What we know about motion at this point is its ends. For I know that the mobile is here or there, but when it is here or there I do not say that it is in motion. Therefore, since we know the ends of motion and we must always proceed from what is more known to the less known, then we must define motion in terms of its ends. For the sake of generality we will names these ends, “that from which” and “that towards which”
The end “from which” is what the mobile posses now, before it has gone somewhere. It is the end that is held in act. The end towards which is what is held in potency, the mobile is not there. We also see that there are any number of points in between these two at which the mobile could be said to be if its motion did not continue on. The mobile has no intrinsic order away or towards either end if it comes to rest at one of these points. If I get up and walk to the doorway and stop, I do not belong to either room more than the other. It is only in motion that I have an order towards or away from some point.
From these considerations we see that motion is a kind of potency, since it does not posses its end. We see also that there is a kind of actuality to motion. The points at which the motion could stop, are closer to the end, so long as we take the order provided by the motion, than the point from which the motion began. Therefore, as long as it is moving it is becoming the end towards which.
Now, the end that towards which is what the mobile holds in potency, before and during the motion. Once the mobile holds the end towards which in act the motion is completed. However, we may still define this in terms of the end from which as the end from which. In order to do this in the language of act and potency, we say that mobile at the end “towards which” is the actuality of the potency. Or in a parallel formulation to Aristotle's definition, it is the actuality of what existed in potency.
So far, we are still speaking of the ends and not of what lies between them. We therefore want to understand the end “towards which” as it exists in potency, not as it existed . Therefore we must understand that potency insofar as it is still in potency. This is our definition: the actuality of what exists in potency, as it is in potency. As Aristotle phrases it, “the actuality of what exists in potency, as such, is motion.”xvii
We have therefore defined motion. The definition is good insofar as it is in terms of what is prior and what is more known. Indeed St. Thomas claims that it is wholly impossible to define motion in another way, by what is prior and more known, than as the philosopher defines it here.xvii This does not mean that all of our difficulties are resolved. However, we have perhaps narrowed down what the difficulties are. Aristotle's approach seems reasonable enough and he is certainly proceeding from common experience. Our question then must turn towards inertial motion. We must see how inertial motion influences our definition. The definition can change by expanding, and going beyond what have said, certainly. However, any sort of claim made by inertial motion which contradicts what has been said, should straight away be seen as an error, for this would be to contradict our experience. The other logical possibility is that inertial motion is not motion, but this would be strange. We speak about these things now, in a vague and indistinct way. For now, let what has been said suffice for our present consideration, and we shall take up these further difficulties later.


xviii omnino impossibile est aliter definire motum per priora et notiora, nisi sicut philosophus hic definit. (In Physicam, Lib. III, lectio 2)

I am looking for some help as I am mulling over inertial motion. Taking Aristotle's definition of motion and Newton's account of inertial motion, there seems to be an inherent contradiction.

In analyzing the account of inertial motion, I am struck by Galileo's thought experiment of the sphere rolling down a plane on one side across the floor and up similarly inclined plane on the other. He posited that if this could be done without friction, the sphere would return to the same height on the opposite plane, and so back again, ad infinitum.
I am struck, however, by several questions when I consider this case. First of all, can there be motion without "friction?" I am inclined to think that it is a necessary condition of motion that it be through a medium which at once inhibits and allows for the possibility of motion. This idea is encouraged by the impossibility of a vacuum. Moreover, (and I know that is an area which you have studied Vincentius) is it right to make such an "abstraction" from motion that we see? Indeed, can the idea of inertial motion even be called abstraction? It seems to be a mathematical fiction, useful for calculation. It is hard for me to see that inertial motion is contained virtually in mobile objects the way mathematicals are contained in bodies. A sign of this is that I see nothing in the nature of matter that makes it impossible that there be a perfect sphere or cube. With inertia, on the other hand, there seem to be many impossibilities. One of which is an infinite effect from a finite agent.
Having laid these questions and considerations before you venerable brethren, I eagerly await your comments, questions and guidance.

I have a question regarding a property of artifacts.

I was pondering this evening about one of the artifacts touched on in Physics II.1, vis. Antiphon's bed. While it is obviously true to say that it has its form qua artifact extrinsically, that is, from the artist, could it also further be said that if there was no one to use a bed, it would merely be shaped wood? In what way does the artificial form exist if the intention of the artist/users of the artifact is lost or absent? I am inclined to say the artificial form no longer exist, or only in a sort of potency, as 'shaped wood.' But I am not sure. How are we to name the 'bed' shape of the bed apart from the artist intention?

An area of both classical and contemporary dispute in interpreting Aristotle’s theory of perception is with regard to how perception involves the sense-organ taking on the sensible form of the perceived object without its matter.[1] In this paper I will consider St. Thomas’ interpretation of Aristotle on this matter with regard particularly to the sense of sight.


It is a noteworthy fact that Aristotle did not see the study of the soul as strictly speaking an independent science.[2] Aquinas was certainly cognizant of this.[3] The study of the nature of the soul is allocated to natural philosophy (phusikoς), which provides the account for the natural principles of the living.[4] Aquinas takes the methods given when natural philosophy is accounted for in principle and applies them to the study of the soul.

Natural philosophy’s common method of beginning from the confused universal and moving to the particular universal is that which explains both the order of Aristotle’s general exposition of sensation, and specifically the sense of sight.[5] It is through Aquinas’ particularly astute exposition of this procedure that we arrive at an account of how the case of sight involves the sense-organ taking on the sensible form of the perceived object without its matter.

Most generally, the powers of the soul are defined by their activities, and these are likewise defined by their objects. Thus objects are the first things which ought to be considered in the study of the soul.[6] So also Aquinas recognizes Aristotle to begin with the sense-objects when explaining the senses because “objects are prior to faculties.”[7]

The sense objects which are most important for Aquinas’s exposition are the special sense objects: “The very essence and definition of each sense consists in its being naturally fitted to be affected by some such object.”[8] These are the objects which are directly and properly perceived (proprie per se sensibilia). Related to this, Aquinas notes that although we cannot but use these terms, the senses are not properly said to be ‘acted on’ by these objects, but are acted on secundum modum of a sensible. Hence the faculty becomes like the object in sensing, but only sensitively and not substantially.[9] This is a key point Aquinas applies to all the senses. At the same time, Aquinas asserts the sense faculties are the acts of bodily organs and, following the principle “whatever is received is received in the mode of the receiver,” the sense faculties receive a similitude of the thing sensed in a bodily and material way.[10] Reconciling these seemingly incongruous principles, namely that the senses sense in a material and bodily way, and also that they are not acted on in the strict sense of the way body acts on body is at the heart of Aquinas’s interpretation of how the sense organ taking on the sensible form of the perceived object without its matter. Showing how Aquinas proposes to resolve this incongruity for all of sensation is outside the purpose of this paper. But I will next examine Aquinas’ subtle exposition of Aristotle which resolves this incongruity in the sense of sight. This exposition, it seems to me, provides the key to explaining how sight involves the eye taking on the sensible form of the perceived object without its matter.

Aquinas, following Aristotle,[11] notes first that “the proper sense-object being that which each sense perceives of itself exclusively, the sense object of which the special recipient is sight is the visible.”[12] The ‘visible’ is simply a broad term used to include both colour and the translucent visible object without a name for things such as glow-worms and certain fungi. This is straightforward enough.

The difficulty is how the visible object (most importantly colour) [13] acts on the sense of sight. Aquinas sees Aristotle’s foundation for the answer to this particular problem in his first showing what colour has to do with visibility, and secondly in settling what is required for colour to be seen.[14] With regard to the first, Aquinas notes along with Aristotle that the object of sight, namely colour, as such is essentially visible.[15] However, colour is essentially visible not in the sense that it is always visible, but insofar that it possesses the intrinsic qualities to be visible. This is clear from the fact that colour manifest itself only in the right conditions. These right conditions are what Aristotle calls the “transparent” and light.[16] Aquinas’ explanation of these conditions settles the second task of explaining what is required for colour to be seen.

The “transparent” are any substances under the ratio of possessing the quality of being receptive to colour, such as air, water, and solids such as glass. These substances are receptive of colour “from without” such that they render themselves visible vis-à-vis the concomitant colour, and hence are not visible per se. Because the presence of light renders this quality actual, light is defined as the act of the transparent as such; that is, it is light which makes this quality of transparency to be in these things.[17] For example, air is a medium between some coloured thing and my eyes, and when light is present in the air, I can see the coloured thing.[18] From this it is clear that the nature of light must be centrally related to how the eye in seeing takes on the colour of the perceived object without its matter. Appropriately Aquinas next carefully examines the nature of light.

Aquinas thus states that it is clear enough that light cannot be a body, because it would follow that the body of light would coexist in the body of the transparent-- an impossibility.[19] Aquinas points out that on the other hand, “it is impossible that any spiritual nature should fall within the apprehension of the senses, whose power, being embodied, cannot acquire knowledge of any but bodily things.”[20] In other words, the light which is perceived by sense is not spiritual [21](natura spiritualis).[22] This seems to open Aquinas to an obvious difficulty: If light is neither a body nor spiritual, then what is it? His reply runs as follows. Though strictly speaking light is not spiritual (in the sense it does not need matter), it is the spiritual or formal quality of light which brings the transparent into act and consequently is the cause of seeing. Seeing is the reception of the form of colour through light; to bring the transparency into act is the formal quality of light.[23] This is to say that it is primarily light as a form which disposes the act of colour to be visible through transparency.[24] But just as light is a formal quality, there must be some matter in which the light exists, albeit the most subtle form of matter, the “most spiritual.”[25] This matter acts on the eye, but not precisely so as to make the eye to see, but merely to act on the matter of the eye which is seeing due to another principle. What is this matter? It is nothing other than the “transparent body.”[26]

This is amendable with modern physiology and optometry which has explained how light waves act on the eye. Light-waves can be understood as the transparent formed by light, i.e. the matter simultaneous with but nevertheless different than the formal of aspect seeing which is the reception of colour through the transparent.[27] This two-fold way the sense is acted upon can be made clearer by taking the easier parallel case of touch. In the act of touching, the object touched makes an indentation on the skin. This indentation is precisely how the sensible matter is materially affected when sensing, but the indentation as such made by the object is clearly not the sensation.[28]

Admittedly, Aquinas seems a bit hesitant in his interpretation here. On the one hand he calls sight the “most spiritual” and “maximum spiritually,” which implies a comparative order with the other senses, such that sight has the same material/formal aspects as the lower senses.[29] On the other hand, he also states in the same place that light is “only a spiritual change,” implying sight is sui generis apart from the other senses.[30] However, in light of Aquinas’ universal statements made about sensation being bodily and his direct arguments against light being strictly speaking spiritual, it seems more reasonable to take him to be formally restating the point that the proper ratio when considering the cause of sight is the formal quality of colour through light and not its material aspect of the transparency.[31] Light acts on transparency, thus enabling the colour to be such that of itself it has its power to impress its likeness on the medium, and also then on the eye. This principled explanation seems best to answer how the sense organ of sight takes on the sensible form of the perceived object without its matter: the matter the eye is affect by is the transparency, which is accidental to sight. It is the colour which is able to impress its formal quality on the eye through the transparency in act, and this is vision.

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[1] Considered by Aristotle in De Anima (hereafter DA) 416b32-418a6. Aristotle, De Anima, Transl. H.G. Apostle (Iowa: The Peripatetic Press 1981).

[2] As Amelie Oksenberg Rorty points out in “De Anima: Its Agenda and Recent Interpreters.” Essays on Aristotle's De Anima, eds. M. Nussbaum and A.O. Rorty (USA: Oxford University Press 1995).

[3] The order of the sciences is the first thing he mentions at the beginning of his commentary on the DA.

[4] I.e. the physical study is concerned with the principles of the living (arche ton zion), c.f. DA 412a7, 403a27-28. If there are any powers of the soul which are able to exist outside the provenance of natural philosophy they then are the concern of the metaphysician, c.f. DA 403b15.

[5] C.f. Physics 184a10-15. Aristotle, Physics, Transl. H.G. Apostle (Iowa: The Peripatetic Press 1980).

[6] DA 415a14-416b31.

[7] Book II Lectio XIII, para. 383. Aquinas, Commentary on Aristotle’s De Anima (hereafter CDA), Transl. By K. Foster and S. Humphries (Indiana: Dumb Ox Books 1994).

[8] Ibid. Book II Lectio XIII, para 387. Thus I am putting aside Aquinas’ explanation of the sensus communis sense objects which are part of sense but not in the same essential way.

[9] Ibid. Book II Lectio XIII, para 381. Aquinas notes that because the pre-Socratics failed to see this distinction they thought the sense-faculties were composed of the same elements as their objects.

[10] CDA Book II Lectio XII, para. 377.

[11] DA 418127-29.

[12] CDA Book II Lectio XI, para. 399.

[13] Aquinas claims the unnamed glowing object of sight is only mentioned by Aristotle incidentally, and that such creature are the way they are due to a certain weakness of not being able to actualize their proper colors seen during the day. The basic point seems fair enough, namely that the glowing object of sight is a certain exception, and thus I will set aside a consideration of it here. At any rate, it turns out that it is in virtue of the normative relationship of colour to seeing that this exception is explained. See CDA Book II Lectio XV, para. 430.

[14] In DA 418a29-418b4 and DA 418b4-9 respectively; c.f. CDA Book II Lectio XIV, para. 400.

[15] DA 418a31 and CDA Book II Lectio XIV, para. 400.

[16] DA 418b1-3.

[17] Again, “it is evident that neither air…nor anything of the sort is actually transparent unless it is luminous.” CDA Book II Lectio XIV, para. 405.

[18] Conversely the transparent in potency is darkness.

[19] DA 418b17. Aristotle gives further arguments for this position in DA 418b20-26, but the force of the above argument is strong enough to prove his point.

[20] CDA Book II Lectio XIV, para. 415-416. This further point is interestingly left unstated in Aristotle, but seems indirectly affirmed in DA 419a25-31.

[21] Ibid. Book II Lectio XIV, para. 416.

[22] Ibid. Book II Lectio XIV, para. 424.

[23] Thus Aquinas places light in the third species of quality, affective quality. C.f. Book II Lectio XIV, para. 420.

[24] This can conversely be said the way Aristotle states it: “to be a color is to be that which causes motion in that which is transparent when in activity.” DA 419a10-11.

[25] “Sed in immutatione visus est sola immutatio spiritualis: unde patet, quod visus inter omnes sensus est spiritualior, et post hunc auditus.” Ibid. Book II Lectio XIV, para. 418.

[26] Ibid. Book II Lectio XIV, para. 421.

[27] This is clearly Aristotle’s conclusion in DA 419a7-15.

[28] As drawn out by Aquinas in Ibid. Book II Lectio XIV, para. 418.

[29] See footnote 80; Ibid. Book II Lectio XIV, para. 418.

[30] Certain contemporary philosophers have focused too much on this apparent hesitancy in Aquinas and have gone on to argue that for Aquinas sensation must be wholly spiritual and in no way material. See for example, Burnyeat, Myles, “Is an Aristotelian Philosophy of Mind Still Credible?,” Essays on Aristotle's De Anima, eds. M. Nussbaum and A.O. Rorty (USA: Oxford University Press 1995). According to Burnyeat, Aristotle thinks the sense-organ taking on a sensible form is nothing more or less than the awareness of that form. He asserts that there is “no physiological process which stands to a perceiver’s awareness of colour or smell as matter to form.” (pg. 15) Because this is open to obvious refutation by modern biology, Burnyeat ultimately proposes to “junk” Aristotle. (pg. 26)

[31] Likewise one would read Aristotle’s arguments against Empedocles: light as a vulgar material body would indeed be “extravagantly postulated” to move instantly across the horizon. Rather, with light’s more formal nature it would seem to move very, very quickly: 186,282.397 miles per second, to be exact.