Jacques Maritain Center: Thomistic Institute

Thomas Aquinas on Phantasia:
Rooted in But Transcending Aristotle's De Anima

Anthony J. Lisska
Denison University

Recent work in analytic philosophy has focused much attention on issues in the philosophy of mind. Part of this attention has been directed towards the philosophy of mind articulated by Thomas Aquinas. That Aquinas is a principal player in issues in the philosophy of mind is not debated.

This interest by analytic philosophers probably goes back to Brentano, whose work, Psychologie vom empirschen Standpunkt, brought the medieval concept of intentionality theory into mainstream analytic philosophy. Brentano wrote the following about intentionality:

The data of our consciousness make up a world which, taken in its entirety, falls into two great classes, the class of physical and the class of mental phenomena . . . . Every presentation of sensation or imagination offers an example of the mental phenomena . . . . Thus hearing a sound, seeing a colored object, sensing warm or cold, and the comparable states of imagination as well, are examples of what I mean . . . .

Examples of physical phenomena, on the other hand, are a color, a shape, a landscape, which I see; a musical chord which I hear; heat, cold, odor, which I sense . . . . These examples may suffice as concrete illustrations of the distinction between the two classes. (1)

Much of this renewed interest in Aquinas in analytic philosophy, in turn, is due to two English philosophers, Peter Geach and probably his most illustrious student, Anthony Kenny. Commenting on Aquinas's contribution to the philosophy of mind, Kenny once wrote the following:

Aquinas's doctrine of the intentional existence of forms remains one the most interesting contributions ever made to the philosophical problem of the nature of thought. (2)

What is important about the intentionality issues in Aquinas is that this is, I submit, one arena in which Aquinas can be considered as a Philosopher. One need not take sides in that wrenching set of issues on whether Aquinas was in fact a theologian whom just happened to be saying a few things of philosophical interest. This claim, of course, I need to spell out in this paper. Furthermore, I wish to establish that not only is Aquinas deeply indebted to Aristotle for his take on the philosophy of mind, but in an important and significant sense, Aquinas moves beyond what I suggest are severe limits in Aristotle's own account, especially involving inner sense.

My approach in dealing with this set of issues in Aquinas's philosophy of mind is much like those claims articulated so well by John Haldane in what he has termed recently, "Analytical Thomism." (3) Moreover, at last November's ACPA meetings, Haldane ended his plenary session paper on contemporary naturalist epistemology with the following suggestion:

What is now needed, however, is a fully perspicuous philosophical account . . . of the nature and operations of what in the Aristotelian-Thomistic tradition are spoken of as the "cogitative powers" and the "active intellect." That might be one of our tasks for the next century." (4)

It is to help move along this project Haldane identified that forms the driving force behind this paper this morning.


Aquinas on Inner Sense.

The particular set of issues I wish to address this morning concern Aquinas's account of sensation and perception. In this analysis, I am interested in concept-formation and the process of abstraction through the intellectus agens only in a periphery way. To be more specific, I am addressing my attention to Aquinas's fascinating and, I think, much neglected account of inner sense, especially the wonderfully interesting analysis of the vis cogitativa.

Right from the beginning, I must indicate what I take to be two different interpretations of inner sense in Aquinas. The text of the Summa Theologiae suggests one account of the concept of phantasia, while Aquinas's Commentary on Aristotle's De Anima offers a different account.

1. In the Summa Theologiae, the inner sense faculty of phantasia is identical with the imagination or Vis Imaginativa. Aquinas writes: "Ad harum autem formarum retentionem aut conservationem ordinatur phantasia, sive imaginatio, quae idem sunt." [I, Q. 78, art. 4.]

2. In the Commentary on the Soul, phantasia is, I suggest, used as a generic concept or "place-holder" covering three distinct faculties of inner sense: the imagination, the vis cogitativa and the sense memory. Aquinas does, nonetheless, mention each of these faculties in his Summa Theologiae account.


The Sententia Libri "De Anima"

The analysis of the vis cogitativa I propose this morning depends on our working through parts of Aquinas's fascinating Commentary on Aristotle's De Anima, whose Latin title is the Sententia Libri "De anima." This book is a wonderful "explicatio textus" of the many issues central to the philosophy of mind. I suggest, furthermore, that in this Commentary, Aquinas develops more fully his account of sensation and perception than one finds elsewhere in his writings. Recently, philosophers have paid more attention to the Commentary. The Leonine edition of the Commentary, edited by the French Dominican, Father Rene-Antoine Gauthier, appeared in 1984. (5) Bob Pasnau has recently published a new translation of the Commentary, (6) which is the first fresh translation of this important work since the classic Foster/Humphries edition first published nearly a half century ago, but thoughtfully re-issued several years ago by Ralph McInerny's Dumb Ox Press. (7) Writing on Aquinas's Commentary in her work on Aristotle's De Anima, Martha Nussbaum, commenting on the issues of functionalism in Aristotle's philosophy of mind raised by Myles Burnyeat, recently wrote the following:

Aquinas' commentary, . . . produced in the thirteenth century, is one of the very greatest commentaries on the work. . ., (and) Aquinas's commentary itself is very insightful; so too are the extensive remarks about Aristotelian soul-body issues contained in the Summa Theologiae." (8)

The dating of the Commentary is a fascinating puzzle-like project in itself. I claim no expertise on these arcane, albeit important matters, to be sure. Nonetheless, recent scholarship by Gauthier suggests that Aquinas at least began if not completed this Commentary, probably in late 1267, while in Rome before leaving in the autumn of 1268 for his second stint at the University of Paris. About this time, he undertook concurrently, so it appears, the composition of the Prima Pars of the Summa Theologiae, where, as we know, Aquinas's account of his philosophy of mind appears in Questions 78-79 and 84-89. Hence, Aquinas was figuring out his own take on issues in the philosophy of mind while wrestling with Aristotle's De Anima. Gauthier and Simon Tugwell both suggest that this was the first of Aquinas's Aristotelian commentaries. (9) I refer those interested to Gauthier's work, and/or to Bob Pasnau's introduction to his own translation of Aquinas's Commentary. (10)

In my judgment, one needs to read carefully Aquinas's exposition and commentary on Aristotle's De Anima in order to witness Aquinas's wrestling at his best with issues in sensation, perception and concept formation. The account of Aquinas's philosophy of mind normally referred to in contemporary discussions is the short analysis in the Prima Pars of the Summa Theologiae, Questions 78-79 and 84-89, plus occasional references to the somewhat whimsical discussions in the Summa Contra Gentiles. While the account of intellectual knowledge found in the Prima Pars of the Summa Theologiae is moderately developed, nonetheless Aquinas treats the important issues of sense knowledge in but two articles of Question Seventy-Eight: Article Three for the external senses and Article Four for the internal senses. Given the interest in philosophy of mind issues revolving around sensation and perception in both modern and contemporary philosophy, one needs to see where Aquinas considers these issues in more detail. And it is to the Sententia libri "De anima" where one turns, especially the exposition and commentary from Chapter/Lectio Ten of Book Two forward and in major sections of Book Three. This corresponds to Book Two, Chapter Five and following in Aristotle. This account of a realist theory of sensation and perception is, in my judgment, more fully developed in this Aristotelian Sententia than in any other place found in the Aquinian corpus.


Aquinas as Dependent Upon Yet Distinct from Aristotle

To begin our discussion, I suggest that Aquinas, in his analysis of inner sense in his Commentary on the De Anima, in at least one important way, differs from Aristotle's own analysis in the De Anima. In discussing phantasia, Aristotle appears to use this term as a generic concept covering any mental act of inner sense. Aristotle, in this conceptually muddy account, does not articulate any differentiated or separable faculties of inner sense. Aquinas, on the other hand, does render a three-fold set of internal sense faculties in both the Commentary and in the Summa Theologiae. One finds this multiplicity of faculties as well in the Summa Contra Gentiles, especially Book Two. Aquinas uses phantasia in his Commentary as a generic term covering three distinct faculties of inner sense

1. Imagination [Vis Imaginativa]--which conserves the sensible forms [as a thesaurus] from the act of awareness of the sensus communis.

2. Vis Cogitativa--which is aware of an individual instance [primary substance] of a natural kind.

3. Sense Memory [Vis Memorativa]--which conserves [also as a thesaurus] the acts of awareness of the vis cogitativa.

Thus the imagination is to the sensus communis as the sense memory is to the vis cogitativa.

Moreover, there are, I suggest, at least three separate and distinct uses of the concept, phantasm. The three faculties of the phantasia--i.e., of inner sense--each have a distinct phantasm. Furthermore, a phantasm is only associated with a faculty of inner sense; it is never part of the external array of sense faculties. Hence, in opposition to some commentators on Aquinas like D. W. Hamlyn, I argue that a phantasm is not a sense datum in any sense of the term; it is never a direct object of sensation. If it were, this would destroy any sense of realism in Aquinas's philosophy of mind. Hamlyn, in Sensation and Perception, suggests a sense datum interpretation for a phantasm. Note the following passage:

On the Thomist view, the phantasmata set up are mental entities and for this reason are like the sensations which are produced by the stimulation of our bodily organs; yet, being somehow representative of the objects which produce them, they are more than mere sensations. They are indeed more like the ideas or impressions of the British Empiricists. . . . Phantasmata, then, are postulated as the mental products of the stimulation of our senses. (11)

This assimilation of a phantasm into a sense datum is, in my judgment, totally mistaken.

Parenthetically, one should note that there are significant differences in the various medieval accounts of inner sense derived from Aristotle. The path finding research undertaken in the first half of the twentieth century by Harry A. Wolfson unearthing how Aristotelian Philosophers in the middle ages discussed the faculties of inner sense is monumental. In his classic historical analysis, "The Internal Senses in Latin, Arabic and Hebrew Philosophic Texts," for instance, Wolfson indicated four different ways in which Albertus Magnus classified the internal sense faculties. (12) It almost appears like each Arabian, Jewish and Christian Philosopher had his own take on how to grapple with inner sense. Often faculties get multiplied. It is important to realize that in the writings of Aquinas, there seems to be no textual evidence that phantasia itself is a separate internal sense faculty along with the other faculties of inner sense. Julius Weinberg, however, once argued that in Aquinas's writings, the phantasia is a separate and distinct faculty of inner sense. Consider the following passage from his A Short History of Medieval Philosophy:

[T]he sensitive [powers] include the functions of the five exterior senses [sight, hearing, smell, taste, and touch] as well as the functions of the interior senses of the common sense, the phantasy, the imagination, the aestimative [or cogitative] capacity, and memory. (13)

This is a position held by several philosophers. As far as I can determine, however, there is neither textual nor structural evidence for this account of Aquinas on inner sense articulated by Weinberg.

In this discussion, I am--at least I think I am--in general agreement with Alasdair MacIntyre, who, in his recently published Dependent Rational Animals, writes the following:

I remain in general convinced by those commentators who have stressed the extent to which Aquinas in his philosophical enquiries was not just an Aristotelian, but often a keenly perceptive interpreter as well as an adapter of Aristotle. (14)

As this analysis unfolds, I intend to show how Aquinas is a "keenly perceptive interpreter as well as an adapter of Aristotle."


The Workings of the Vis Cogitativa.

We must now begin with the vis cogitativa. The incidental object of sense, mentioned but sketchily by Aristotle in the De Anima, is, I intend to establish, the direct object of awareness of the internal sense Aquinas calls the vis cogitativa. When discussing perception in Aquinas, most philosophers, scholastic and analytic, have not considered the exact nature of this faculty--the vis cogitativa--in detail. Some fifty years ago, the late Father George Klubertanz published The Discursive Power.(15) This is the only book length treatment of the vis cogitativa that surfaced during the research undertaken for this project on inner sense. Several articles have appeared, most written in the second quarter of the twentieth century. Leo White's recently completed dissertation at Catholic University is a welcome addition to these earlier studies. An article published in an early number of The Modern Schoolman probably best describes this situation: "A Forgotten Sense: The Cogitative according to St. Thomas Aquinas."(16) Christopher Martin, in his generally quite perspicuous commentaries on topics in Aquinas, shrugs his shoulders, it appears, by remarking that ". . . it is impossible here to enter into a discussion of Aquinas's views on (the vis cogitativa)." (17) Let us hope that this morning we may undertake a discussion of Aquinas on the vis cogitativa. This analysis will, I trust, assist immensely in our discussion of Aquinas's realist account of sensation and perception.

The vis cogitativa in Aquinas has, I submit, two functions.

1. To be aware of an individual as an individual.

2. To recognize an individual as a member of a natural kind.

As Aquinas writes: "Hence, the vis cogitativa is aware of a human person as this human person." In his Commentary on Aristotle's Metaphysics, Aquinas explains this facet of the mental act of the vis cogitativa in the following manner:

In human beings, the next thing above memory is experience, which some animals have only to a small degree. For an experience arises from the association of many singular [intentions] received in memory. And this kind of association is proper to human beings and pertains to the vis cogitativa [also called the particular reason], which associates particular intentions just as universal reason associates universal ones.

Commentary on the Metaphysics, # 15.

In discussing the structure of the vis cogitativa, Aquinas introduces the concept of what later commentators refer to as the intentiones non-sensatae or intentiones insensatae. These are acts of awareness to which there is not an object in the external world that acts causally on the sense faculty. Early on in the Summa Theologiae, Aquinas writes the following about the three general kinds of sensibles: the proper sensible, the common sensible, and the incidental object of sense.

Sense knows things from being impressed with their likeness. Now this likeness can be taken at three stages. First, immediately and directly [primo et per se], as when the likeness of color is in the sight; so also with the other proper sensibles in their appropriate senses. Secondly, directly but not immediately [per se, sed non primo], as when the likeness of bodily shape or size is in the sight; so also with the sense-objects shared through several senses--i.e., the common sensibles. Thirdly, neither immediately nor directly [nec primo nec per se, sed per accidens], as when the likeness of a person is in the sight. She is not there [ i.e., in the sight per se] because she is a human person, but because she is a colored object; [The incidental object of sense].

Summa Theologiae, Q. 17, a. 2. [Italics and underlining not in the original.]

Note here the third sense of awareness--the "likeness" [similitudo] is "neither immediately nor directly" impressed on the sense faculty. This is, I suggest, a very important part of Aquinas's analysis of sense perception.

In considering the workings of both the vis aestimativa and the vis cogitativa, Aquinas discusses the role of the intentio non-sensata. It is now time to look seriously at some Aquinas texts. Note the following passages, beginning with a text from the Summa Theologiae, where Aquinas writes explicitly about "intentions, which are not received through the senses":

Furthermore, for the apprehension of intentions, which are not received through the senses, the aestimative power is appointed; and for their preservation, the memorative power, which is a storehouse [thesaurus] for such intentions. . . .

Summa Theologiae, I, Q. 78, a. 4. [Italics not in the original.]

In De Veritate, Aquinas makes much the same point: "the imagination, which is the storehouse of forms received by the senses, . . . [and] . . . the memory, for particular apprehensions not received from the senses." De Veritate, Vol. II, Q. 10. [Italics not in the original.].

In discussing the vis aestimativa, Aquinas writes the following:

Again, we must observe that if an animal were moved by pleasing and disagreeable things only as affecting the sense, there would be no need to suppose that the animal has a power besides the apprehension of those forms which the senses perceive, and in which the animal takes pleasure, or from which it shrinks with horror. But the animal needs to seek or to avoid certain things, not only because they are pleasing or otherwise to the senses, but also because of other advantages and uses, or disadvantages; just as the sheep runs away when it sees a wolf, not because of its color of shape, but as a natural enemy. So too, a bird gathers together straws, not because they are pleasant to the sense, but because they are useful for building its nest.

Summa Theologiae, I, Q. 78. A. 4. [Italics not in the original.]

Another text makes much the same point:

Animals, therefore, need to perceive such intentions, which the exterior sense does not perceive. Now some distinct principle is necessary for this, since the perception of sensible forms comes by an immutation caused by the sensible, which is not the case with the perception of the above intentions.

Ibid., [Italics not in the original.]

In Aquinas's Commentary On the Soul, we find the following text:

But the lower animal's awareness of individualized notions is called natural instinct, which comes into play when a sheep, for example, recognizes its offspring by sight, or sound, or something of that sort.

Commentary on the Soul, # 397.

And in the Summa Theologiae, we read the following:

Now, we must observe that regarding sensible forms there is no difference between human persons and other animals. For they are similarly immuted by external sensibles. . . . But there is a difference as to the above intentions [i.e., of the internal senses and intentiones non sensatae]: for other animals perceive these intentions only by some sort of natural instinct, while human persons perceive them also by means of a certain comparison. Therefore, the power, which in other animals is called the natural aestimative, in humans is called the cogitativa, which by some sort of comparison discovers these intentions [homo autem etiam per quandam collationem]. Therefore, it is also called the particular reason, to which medical persons assign a particular organ, namely, the middle part of the head. For it compares individual intentions, just as the intellectual reason compares universal intentions [in homine dicitur cogitatva, quae per collationem quandam huismodi intentiones advenit.].

Summa Theologiae, I, Q. 78, a. 4.

The Commentary has the following text:

Having seen how we should speak of the absolute or essential sense objects, both common sensibles and proper sensibles, it remains to be seen how anything is a sense object "incidentally." Now for an object to be a sense object incidentally, it must first be connected accidentally with an essential sense object; as a human person, for instance, may happen to be white, or a white thing may happen to be sweet. Secondly, the one who is sensing must perceive it. If it were connected with the sense object without itself being perceived, it could not be said to be sensed incidentally. But this implies that with respect to some cognitive faculty of the one sensing it, it is known, not incidentally, but absolutely. Now this latter faculty . . . [is] the vis cogitativa.

Commentary on the Soul, # 395.

And the following:

Thus as soon as I see anyone talking or moving herself, my intellect tells me that she is alive and I can say that I see her alive. But if this apprehension is of something individual, as when, seeing this particular coloured thing, I perceive this particular person or this particular beast, then the cogitative faculty [in the case of human persons at least] is at work, the power which is also called the "particular reason" because it correlates individualized notions, just as the "universal reason" correlates universal ideas.

Ibid., # 396.

Throughout these texts, it is apparent that Aquinas links animal awareness with the rudimentary awarenesses of human beings. Again, this is not a Cartesian or dualist meta-philosophical move. In Dependent Rational Animals, Alasdair MacIntyre writes about this set of issues, which he believes philosophers have neglected for too long a time.

But some commentators . . . have failed to ask the relevant questions about the relationship between our rationality and our animality. They have underestimated the importance of the fact that our bodies are animal bodies with the identity and continuities of animal bodies, and they have failed to recognize adequately that in this present life it is true of us that we do not merely have, but are our bodies. (18)

Given these texts on inner sense, we note immediately that Aquinas pays special attention to the knowing apparatus and the mental acts of non-human animals. This suggests strongly the anti-dualist characteristic of Thomas's meta-philosophy. Aquinas once wrote that "Anima mea non est ego." (19) In no sense of the term is Aquinas a Cartesian dualist in his metaphysics or his philosophy of mind. The analysis of inner sense enables us to tease out these important non-dualist properties.


The Possibility of Perception of Individuals.

So far, I have argued that Aquinas indeed develops and pushes farther the analysis of inner sense that Aristotle suggests in the De Anima. This is an advance over the limited faculty psychology that Aristotle articulated. Furthermore, I have suggested that it is by the use of an intentio non-sensata that Aquinas comes to terms with the incidental object of sense. Now, why would Aquinas opt for this kind of analysis?

In responding to this question, I intend to show that Aquinas opts for a meta-philosophy totally at variance with what we find in modern philosophy. Aquinas builds his ontology first, and then his philosophy of mind and his epistemology follow from the ontological analysis already constructed. So, not only is Aquinas not a Cartesian in metaphysical dualism, but in a deeper sense, his approach to undertaking the activity of philosophy is worlds apart from the Cartesian method. There is, I suggest, a fundamental meta-philosophical difference between Aquinas and most practitioners of modern philosophy. In this, I am in agreement with Scott MacDonald who once wrote the following:

Aquinas does not build his philosophical system around a theory of knowledge. In fact, the reverse is true: he builds his epistemology on the basis provided by other parts of his system, in particular, his metaphysics and psychology. (20)

Writing about Aquinas, John Haldane argued in the same vein:

Our knowledge of the external world is the starting point for philosophical reflection, the task of which is not to justify this knowledge but to explain it; to give an account of the scope of cognition, its genesis and its operations." (21)

To paraphrase from the writings of the late Henry Veatch--Aquinas does not adopt the "Transcendental Turn" when doing his philosophy. He does not set up a set of epistemological criteria elucidating a "foundationalist epistemology." Aquinas does not attempt to justify our awareness, but rather to explain the possibility of those acts of awareness.


A World of Primary Substances.

I suggest that what is driving Aquinas at this point is the following issue in the philosophy of mind: what must be the case in order for us to be aware of primary substances? A primary substance--the individual of a natural kind--is the principal metaphysical category in Aquinas's ontological scheme of things. This is, as we know, a combination of materia prima and forma substantialis, modified by a set of accidental or incidental forms. Aquinas argues that this is the best metaphysical account available for the things of the world. Each individual thing naturally occurring in the world is an instance of a natural kind. The forma substantialis determines the set of necessary properties that "define" the category of the natural kind. And, as we know, materia prima is the principle of individuation.

Aquinas next asks--how can be we aware of these primary substances? It is through the process of the external sensorium--the external senses and the sensus communis--that we are aware of the set of incidental forms. It is through the rather complicated process of abstraction through the work of the intellectus agens and the intellectus possibilis that we are aware of the substantial form that determines the natural kind.

But, if the principal ontological category is the individual--the primary substance--then wouldn't it seem plausible that Aquinas would postulate some sort of process so that a human knower might be aware of this fundamental category? It is at this point that the vis cogitativa with its structured mental act of awareness using an intentio non-sensata comes into play.

I suggest, moreover, that it is through an analysis of the vis cogitativa that Aquinas can justify a distinction between sensation and perception. In one sense, Aquinas writes like Thomas Reid, who, as William Kneale once suggested, rescued the word, "perception" from the early modern philosophers who had played such havoc with this epistemological concept. (22) In early modern philosophy, Kneale further suggests, the term, "perception" ceased to have any clear meaning. Hence, an empiricist like David Hume thought himself entitled to use "perception" as an "omnibus word" for whatever goes on in the mind. On matters of perception, Aquinas differs radically, I suggest, from Hume. It is, furthermore, by means of the vis cogitativa that Aquinas offers and justifies a category difference between sensation and perception.


The Klubertanz/Kneale Analysis of the Vis Cogitativa

In his The Discursive Power, Klubertanz argued that the function of the vis cogitativa, in a manner analogous to the vis aestimativa, is that which recognizes the good to be done here and now in a particular situation. Kneale, in commenting on perception in Aquinas, offered the same suggestion regarding an elucidation of intentiones non-sensatae with the vis cogitativa. It is through these unsensed intentions, so Kneale argues, that a human perceiver discerns the useful or the good in particular situations. Kneale writes as follows.

Animals are said to have a faculty other than sense by which they perceive intentiones of usefulness and harmfulness. But the peculiar talk of perceiving intentiones into which St. Thomas falls here seems to have been suggested to him by the peculiarity of the mental occurrence we call seeing a thing as useful or harmful. (23)

The analysis suggested in this paper, however, is that the awareness of the individual as an individual is the first and primary purpose of the vis cogitativa. The apprehension of "the useful or the good" is a second order awareness following upon the primary awareness which is of a specific individual primary substance. This is how Aquinas accounts for the awareness of the principal ontological category in his metaphysics--the primary substance. In his classic account of sensation and perception in Albert, Aquinas and Siger, Edward Mahoney appears to agree with the Klubertanz and Kneale account of the intentional awareness of the vis cogitativa. (24)


The Importance of This Account.

Without this structured awareness on the part of the vis cogitativa, a human knower would be, I submit, deficient in at least two ways; and Aquinas was not one to permit philosophical deficiencies to appear in his ontological accounts.

1. A human knower would be unable to be aware directly of the fundamental ontological categories in Aquinas's metaphysics, which are individuals of natural kinds; these are, of course, primary substances.

2. A human knower would be less able to "abstract" the essence from the phantasms in the sense memory using the intellectus agens.

The explicatio textus suggested here is remarkably similar, it would seem, to the method articulated by James Gibson in discussing the evolutionary development of human sense organs. It is through this evolutionary development that a human knower can make one's way around the environment. While Gibson does not affirm an ontology of primary substances, nonetheless he does consider the role the environment plays in determining how sense organs and faculties have developed and function. The same is true, mutatis mutandis, for Aquinas. (25) Haldane is quite explicit about this epistemological naturalism in Aquinas. Interestingly enough, Haldane suggested recently that Aquinas and Willard Quine share some important meta-philosophical themes, since in the philosophy of mind, "both are philosophical naturalists." (26)

According to the texts, it appears that Aquinas suggests that the vis cogitativa is the faculty of inner sense by which we are aware of an individual as a member of a particular kind. This mental act is neither identical with nor co-extensive with the mental act of concept-formation, which, of course, is what Aquinas identifies with the role of abstraction through the intellectus agens. To know a concept is to have an awareness of the "nature" or "essence" of a thing. This nature is common to many; hence, the individual concretum as individual is precluded from being the intentional object of the intellectus agens [abstracting the essence] or the intellectus possibilis [knowing the essence]. Aquinas articulates this position in the Summa Theologiae with the following proposition: "Unde intellectus noster directe non est cognoscitivus nisi universalium." [I, Q. 86, a. 1] It is precisely at this point in the discussion that the vis cogitativa comes into play. It is this inner sense faculty which conditions the mental act to be aware of an individual as a member of a "kind." This does not mean that it is an awareness of a "nature" or "essence." This is the role of first intentional awareness on the part of the intellectus possibilis. In other words, the vis cogitativa is not aware of "human nature as human nature," but rather as Megan the human person and Elin the human person. This awareness comes about through the working of the phantasms in the vis cogitativa. The phantasm peculiar to the vis cogitativa "conditions" or "colors" the mental awareness of the vis cogitativa so that it interprets the object--the primary substance--in the external world in a unique way. To be sure, this suggests an almost Kantian interpretation regarding a structured act of awareness. The structure of the act of awareness of the vis cogitativa is determined by the phantasms; the phantasms in turn come about only because of the range of the perceiver's experience. In other words, the vis cogitativa "interprets" an object as an individual of a kind and not merely as a unified concrete whole composed of a set of proper and common sensibles. This, in effect, distinguishes the vis cogitativa from the sensus communis. This is evidence for placing the sensus communis in the external sensorium and not in the internal sensorium even though Aquinas classifies it as an internal sense. (27)


Ontological Realism.

I suggest that this interpretation of Aquinas on inner sense saves the metaphysical realism on which he builds his philosophical system. This is not, it seems to me, an arcane or idle philosophical question. Writing in the most recent issue of New Blackfrairs, Catherine Pickstock asks the following question, and I think not rhetorically:

How should one respond to the death of realism, the death of the idea that thoughts in our minds can represent to us the way things actually are in the world? For such a death seems to be widely proclaimed by contemporary philosophers. (28)

To reiterate briefly, Aquinas, like Jimmy Gibson, assumes that there is a world around us. He asks, like Gibson does, what must be necessary in order for us to know and understand this world of individuals. Gibson would appeal to evolutionary development in order to explain how our perceptual apparatus developed. Nonetheless, Gibson--and if John Haldane is correct, Quine too--and Aquinas adopt, I submit, the same meta-philosophical approach--i.e., how do we explain our awareness of the world around us? (29) As Haldane once noted in "Mind-World Identity Theory and the Anti-Realist Challenge," in his "metaphysics and cognitive psychology, . . . Aquinas advocates strong versions of both epistemological and ontological realism. . . . ." (30)

This account renders more perspicuous the structural connection between the vis cogitativa and its phantasms, the sense memory and its phantasms, and the power of abstraction with the intellectus agens. If the sense memory stores the acts of awareness of the vis cogitativa, then this provides a more perspicuous array of phantasms on which the intellectus agens might act in "abstracting" the set of essential properties that determine a natural kind. Moreover, this interpretation renders more understandable the famous "army in retreat" metaphor that Aristotle uses in Chapter Nineteen of Book Two of the Posterior Analytics, and on which Aquinas comments in his discussion of that book of Aristotle's logic.

In his philosophy of mind, Aquinas, like Aristotle before him, rejects the analysis of a mental act in the Platonic mode of "knowledge as acquaintance." This is a rejection of what I might call the "diaphanous mental act." Readers familiar with G. E. Moore will recall Moore's discussion of intentionality in terms of "the diaphanous arrow of consciousness." Aristotle and Aquinas adopt what I will call a "structured mental act." There are two important intentional structures in Aquinas's philosophy of mind: (a) The intellectus agens, and (b) the vis cogitativa. Both are needed in order for Aquinas to provide an account of an awareness of essential properties. Both get beyond the direct data from the external senses. In discussing Gilson on Aquinas's philosophy of mind, John Peterson once wrote that "the senses carry a message which they cannot themselves interpret." (31) Peterson and Gilson refer here to the intellectus agens; I suggest that the vis cogitativa also needs to be included in this discussion.


Substance and Classical British Empiricism

If this analysis is correct, it would appear that the paramount example of "inner sense" for Aquinas is the vis cogitativa. It is by means of this faculty that Aquinas is able to transcend the limits of most empiricist and certainly all phenomenalist accounts of sensation and perception.

An important corollary of this discussion is the role that primary substance plays in the functioning of the vis cogitativa. In his ontology, Aquinas, in the manner of Aristotelian realism, suggests that the basic and fundamental things in the external world are primary substances. We have seen that Aquinas, again following Aristotle, adopts a three-fold division for the objects of sense knowledge: the proper sensibles, the common sensibles, and the incidental object of sense. There is no analogue in classical British empiricism, for instance, for the incidental object of sense. Given the bundle view of perception espoused by Berkeley in The Principles and Hume in The Inquiry, among other places, theoretically there is no room left for the incidental object of sense. Berkeley and Hume analyze an individual in terms of a collection of sensible properties. Berkeley wrote as follows in The Principles:

Thus, for example, a certain color, taste, smell, figure and consistency, having been observed to go together, are accounted one distinct thing, signified by the name "apple." Other collections of ideas constitute a stone, a tree, a book, and like sensible things. (32)

In his An Inquiry Concerning Human Understanding, Hume used the same analysis, substituting a peach for an apple:

As our idea of any body, a peach, for instance, is only that of a particular taste, color, figure, size, consistency, etc., so our idea of any mind is only that of particular perceptions without the notion of anything we call substance, either simple or compound. (33)

These texts from Berkeley and Hume indicate that the paradigm of perception accepted by these empiricists is what we might call "the bundle view." A physical object is nothing more than a collection--i.e., a set of sense qualities--that in British empiricism would be the set of primary and secondary qualities. On the other hand, Aquinas, in espousing a "thing consciousness" paradigm, goes beyond the limits of the bundle view paradigm. The vis cogitativa is what provides for this more sophisticated account.

In his De Anima, Aristotle spells out in some detail the structure and content of the proper and the common sensibles. But, as we noted earlier, when he comes to the incidental object of sense, Aristotle has precious little to say. Aquinas, in suggesting that it is by means of the vis cogitativa that we account for our perception of the incidental object of sense, goes beyond the limits found in Aristotle's account of sensation and perception. Moreover, and this is the important cash value claim of this analysis for work in the philosophy of mind, both Aristotle and Aquinas transcend the limits entailed by the bundle view paradigm adopted by the British empiricists.

A primary substance, to reiterate briefly, is an individual thing of a certain natural kind. The "natural kind" refers to a species that is determined by the substantial form of the thing. The vis cogitativa appears to be the faculty by which the perceiver is aware of a primary substance as a thing and not merely as a bundle of sensations. This, again, requires an interpretive function on the part of the vis cogitativa. In effect, inner sense goes beyond the data of the external sensorium. This is accomplished through an intentio non-sensata and the structured mental act of the vis cogitativa.

Accordingly, Aquinas not only has primary substances in his ontology, but his philosophy of mind is structured so that the perceiver can be aware of these primary substances. Simply put, the vis cogitativa explains the possibility of the awareness of individual substances. The end result is that Aquinas asserts the two following propositions:

1. There are individual things [primary substances] in the external world.

2. We are aware of these individual things [primary substances] as individuals and not as mere collections of proper and common sensibles.

The possibility of our being aware of individual things is accounted for by means of the phantasm-structured vis cogitativa. The external sensorium is aware of unified wholes of proper and common sensibles. At this point in the process--i.e., the external sensorium--Aquinas's account is similar structurally to the bundle view paradigm articulated by Berkeley and Hume. The vis cogitativa, however, is aware of the primary substance as a primary substance--an individual. The mental act of the vis cogitativa renders the awareness of "unified whole" into an awareness of an individual of a natural kind. In effect, it is because of the vis cogitativa that Aquinas can distinguish between sensation and perception, and, a fortiori, transcend the limits of modern and contemporary British empiricism.

The importance of this sense faculty in Aquinas's philosophy of mind is obvious. An experienced datum of our perceptual lives, the pre-analytic datum, is that we, as perceivers, seem to be directed primarily towards things rather than just to collections of qualities. Accordingly, Megan--as a perceiver--is aware of Elin--as an individual--and not merely a collection of proper and common sensibles. Contemporary philosophers who claim that we ordinarily talk as if we perceive things and not sense data point out this same pre-analytic datum. John Wisdom, for example, once remarked that philosophers must consider the difference between what he called "sense statements" and "thing statements." (34) In addition, this distinction was reiterated often in the writings of Roderick Chisholm. (35) Of course, this analysis squares with the data used in Gestalt Psychology.

With his discussion of the vis cogitativa and its mental act, Aquinas accepts in principle Wisdom's distinction and is concerned about the same set of issues. Through his analysis of the vis cogitativa, Aquinas undercuts the sense data theories of early twentieth century epistemology found in the writings of Russell, Moore, Price and Ayer, and also the early modern empiricism of Locke, Berkeley and Hume. Aquinas accomplishes this by suggesting, in effect, that our experience is of things rather than of sense data. In addition, by using a meta-philosophical methodology entailing a faculty psychology, Aquinas provides the philosophy of mind machinery necessary to explain the possibility of an act of awareness of an object beyond the immediate data of the proper and the common sensibles. There is a similarity with Peter Strawson, who once claimed that "particulars" are the basic elements of a human perceiver's conceptual scheme. Accordingly, Aquinas, like Strawson, suggests that it is a mistake to claim that human perceivers are primarily and fundamentally aware of bundles of sense data. To the contrary, human perceivers have a direct "thing consciousness" or "individual consciousness." Furthermore, this "consciousness" and "intentional awareness" are rudimentary for human perceivers.

It is appropriate, I suggest, to compare the acts of awareness of the vis cogitativa with what is common sensibly referred to as "experience." Recall once again the "army in retreat" metaphor in the Posterior Analytics. The first time Megan sees Elin, she obviously does not recognize her as Elin. As far as being Elin to Megan the perceiver using only the external senses, Elin is no more than a mere bundle of sensations. Nonetheless, the vis cogitativa is already geared--or structured--towards interpreting this object of awareness as an individual, and an individual of a natural kind. After Megan has begun to know Elin, then she immediately recognizes Elin "as Elin" as soon as Elin comes into view. It is important to realize that Aquinas does not claim that we remember this particular bundle of sensations--i.e., the concrete whole--as Elin. Rather, we perceive her immediately to be Elin. Yet "being Elin" is not some type of discrete, identifiable individuating property, which is directly perceivable in the external world. "Being Elin" is not a proper or a common sensible. Elin is, however, an incidental object of sense. This is an important part of Aquinas's theory of sense perception.

Accordingly, Aquinas claims that it is by means of the internal sense of the vis cogitativa that a human perceiver is able to "immediately perceive" an individual as an individual. In other words, when Megan is directly aware of Elin, she is not remembering what she saw earlier as this same bundle of sensations nor is Megan exercising any act of judgment. Quite the contrary, she is directly aware that this "concrete whole" is Elin--a particular individual of a natural kind. That such an individual property is imperceivable per se is, furthermore, consistent with Aquinas's position on individuation. The ontological problem of individuation is resolved in Aquinas's metaphysics by the assertion that "materia prima" is the principle of individuation. Accordingly, there is no postulation of an individualizing form similar to the haeccaeitas of Duns Scotus. It follows from what I take to be Aquinas's "axioms of intentionality" that only a form can be knowable directly. Since materia signata quantitate, which is the direct opposite of a form, is the individuator, there is nothing as such in the external world which could be the object of the mental act of direct sensation regarding an individual as an individual. Therefore, Aquinas makes use of the vis cogitativa as the faculty of the internal sensorium, which accomplishes our awareness of individuals, and not just of "concrete wholes."


Back to Aristotle's De Anima

If I am correct in this analysis of Aquinas on inner sense, especially the vis cogitativa, then this indicates at least one place where Aquinas, as a philosopher, is dependent upon but goes beyond what he finds in Aristotle's texts on the philosophy of mind. In fact, as far as I have been able to discover, Deborah Modrak is the only philosopher who suggests that Aristotle himself might have some sense of the intentiones non-sensatae. She writes: "The sensory basis for the perception of an individual object does not fully determine the content of the perception." She goes on to suggest that ". . .the percipient plays an active role in shaping the content of an individual perception." Also, "the perception of an incidental object arises spontaneously in the perception when past and present experiences are conducive to the apprehension of the incidental object in question. . . . Moreover, there is no textual evidence for attributing to Aristotle a narrow notion of perception that would exclude interpretation."(36) However, Aristotle, in his De Anima, does not build the philosophy of mind machinery needed to account for this act of awareness. Aquinas, on the other hand, does, and this is the role of the vis cogitaitva.

In concluding this discussion of Aquinas and the perception of individuals through inner sense, I suggest that the following seven propositions should be affirmed:

1. The vis cogitativa is the faculty, which perceives the individuals of the world. In Aquinas's ontology, these would be the primary substances, each of which is a hoc aliquid.

2. The perception is of an individual of a natural kind.

3. This awareness transcends the limits of the external senses. The external senses are limited, given the structure of Aquinas's philosophy of mind, to an awareness of proper and common sensibles.

4. The awareness by the vis cogitativa is an "active contribution" to the perceiving process necessary to be aware of individuals as individuals and not bundles of sensations.

5. It follows from 1 through 4 above that Aquinas developed a philosophy of mind on the perceptual level necessary to provide for an awareness of individuals.

6. This account of the awareness of an individual is in addition to the usual account of the reflexive awareness of the intellect so common to explications of Aquinas's philosophy of mind. [Cf. Summa Theologiae, I, Q. 86, a 1: "Whether the Intellect knows Particulars"--i.e., "Utrum Cognoscat Singularia"].

7. It follows that Aquinas offers an account for the awareness of individuals as individual hoc aliquids on the level of sense perception.

This concludes my analysis--an explicatio textus--into the somewhat murky region of inner sense--phantasia--in Thomas Aquinas. This is a bit of philosophy of mind rooted in Aristotle's De Anima, but an account developed so much further. I trust this account is sufficiently perspicuous in order to help meet what John Haldane suggested as "one of the tasks for the next century."


1. Franz Brentano, Psychologie vom empirischen Standpunkt, found in Realism and the Background to Phenomenology, edited by Roderick M. Chisholm and translated by D. B. Terrell (Glencoe, Illinois: The Free Press, 1960), pp. 39-41.

2. Anthony Kenny, Aquinas (Past Masters Series): (Oxford: Oxford University Press, 1980), p. 80.

3. John Haldane, "Analytical Thomism: A Prefatory Note," The Monist, Vol. 80, No. 4 (October, 1997), pp. 485-86; this volume is entitled "Analytical Thomism." Also, John Haldane, "What Future has Catholic Philosophy," American Catholic Philosophical Quarterly, Vol. LXXI (Annual Supplement, Proceedings of 1997 Annual Meeting), pp. 77-90. The April, 1999 issue of New Blackfriars was devoted entirely to a discussion of Analytical Thomism.

4. Haldane, "Insight, Inference and Intellection," in Proceedings of the American Catholic Philosophical Association, "Insight and Inference," Vol. 75, 1999 (Bronx, NY: Fordham University, 2000), p. 43.

5. [Paris: Vrin, 1984].

6. Robert Pasnau, trans. Thomas Aquinas: A Commentary on Aristotle's De anima (New Haven and London: Yale University Press, 1999).

7. Aristotle's De Anima in the Version of William of Moerbeke and the Commentary of St. Thomas Aquinas, Kenelm Foster and Silvester Humphries (New Haven: Yale University Press, 1951); Dumb Ox Books (Notre Dame, IN, 1994).

8. Martha C. Nussbaum, "The Text of Aristotle's De Anima" in Essays on Aristotle's De Anima, edited by Martha C. Nussbaum and Amelie Oksenberg Rorty (Oxford: The Clarendon Press, 1992, 1995), p. 4.

9. The recently published English translation of Jean-Pierre Torrell's St. Thomas Aquinas: The Person and His Work (Washington, DC: The Catholic University of America Press, 1996), p. 172, contains a thoughtful discussion of Gauthier's research.

10. In his excellent study of Aquinas, Simon Tugwell notes the following concerning Aristotelian Commentaries by Aquinas:

Also towards the end of his time in Rome, Thomas composed what may have been his first fully-developed Aristotelian commentary, on the De Anima, and it is not unreasonable to postulate a connection between this commentary and the fact that Thomas was writing about the soul in the first part of the Summa. In the same way the commentary on Aristotle's Ethics, at least in its final form, seems to be related to the composition of the second part of the Summa.

Cf. Simon Tugwell, "Introduction: Thomas Aquinas," in Albert and Aquinas: Selected Writings (Manwah, NJ, The Paulist Press, 1988).

11. D. W. Hamlyn, Sensation and Perception (London: Routledge and Keegan Paul, 1961), pp. 46-51.

12. Harry Austryn Wolfson, "The Internal Senses in Latin, Arabic, and Hebrew Philosophic Texts," Harvard Theological Review, XXVIII, # 2 (April, 1935), pp. 116-118. Wolfson's article is a classic historical analysis of the development of the various positions medieval philosophers affirmed in discussing the function of the internal senses.

13. Julius R. Weinberg, A Short History of Medieval Philosophy (Princeton: Princeton University Press, 1966), p. 201.

14. Alasdair MacIntyre, Dependent Rational Animals (Chicago: Open Court, 1999), p. xi.

15. George Klubertanz, The Discursive Power (St. Louis: The Modern Schoolman Press, 1952).

16. Julien Peghaire, The Modern Schoolman, 20 (1942-3), pp. 123-140; 210-229.

17. Christopher Martin, The Philosophy of Thomas Aquinas (London: Routledge, 1988), p. 122.

18. MacIntyre, op. cit., p. 6; Patrick Lee argues in a similar manner in his article, "Human Beings are Animals," in Natural Law and Moral Inquiry, edited by Robert P. George (Washington, DC: Georgetown University Press, 1998), pp. 135-151.

19. Commentary on St. Paul's First Letter to the Corinthians, 15: 17-19, found in Aquinas: Selected Philosophical Writings, Edited by Timothy McDermott (Oxford: Oxford University Press, 1993), pp. 192-193.

20. Scott MacDonald, "Theory of Knowledge," in Norman Kretzmann and Eleonore Stump, The Cambridge Companion to Aquinas (Cambridge: Cambridge University Press, 1993), p. 160.

21. Haldane, op. cit., p. 38.

22. William Kneale, "Analysis of Perceiving," found in Perception, edited by F. N. Sibley (London: 1971), p. 68.

23. Kneale, Ibid., p. 68.

24. Edward Mahoney, "Sense, Intellect and Imagination in Albert, Thomas, and Siger," found in The Cambridge History of Later Medieval Philosophy, edited by Norman Kretzmann, Anthony Kenny and Jan Pinborg (Cambridge: Cambridge University Press, 1982; 1984), pp. 602-622.

25. I wish to acknowledge the assistance my Denison colleague, Harry Heft, provided in this discussion of James Gibson's work.

26. Haldane, Op. Cit., p. 39.

27. One needs here to distinguish the external senses from the internal senses, and the external sensorium from the internal sensorium. The former pair is distinguished by the location of the sense faculties, while the latter pair is distinguished by the intentional act itself. The faculties of the internal sensorium--the imagination, the vis cogitativa and the sense memory--all require phantasms.

28. Catherine Pickstock, "Imitating God: The Truth of Things According to Thomas Aquinas," The 1999 Aquinas Lecture, New Blackfriars, July/August, 2000 (Vol. 81: Nos. 953/954), p. 308.

29. While I have suggested a certain affinity with Kant on inner sense, this does not entail that my analysis of Aquinas on the vis cogitativa is either connected with or dependent upon what has been called "Transcendental Thomism."

30. Haldane, "Mind-World Identity Theory and the Anti-Realist Challenge," in Reality, Representation and Projection, edited by John Haldane and Crispin Wright (Oxford: Oxford University Press, 1993), p. 24.

31. John Peterson, Realism and Logical Atomism: (University, AL: The University of Alabama Press, 1976), p. 7.

32. George Berkeley, A Treatise Concerning the Principles of Human Understanding, # 1.

33. David Hume, An Inquiry Concerning Human Understanding (Hendel Edition), p. 194.

34. John Wisdom, "Philosophical Perplexity," found in Morris Weitz, 20th Century Philosophy: The Analytic Tradition (New York: The Free Press, 1966), p. 292.

35. For example, Roderick M. Chisholm, "On the Observability of the Self," Philosophy and Phenomenological Research," 30 (1969), pp. 7-21.

36. Deborah K. W. Modrak, Aristotle: The Power of Perception (Chicago: The University of Chicago Press, 1987), pp. 69-70.