Chapter IV -- 11

St Thomas now turns to how the intellect operates.[1]

St Thomas establishes that our intellect operates by abstracting from the images or phantasms produced in sense-perception.[2]

St Thomas makes this important distinction: we perceive not the ‘sensible species’ but the sensible object by means of the ‘sensible species’, and we know not the ‘intelligible species’ but by means of the ‘intelligible species’.[3] In the case of the sensible species, the ‘species’ is the sense-perception of the sensible object; in the case of the intelligible species, the ‘species’ is the intelligible form or ‘image’ of the universal, or objective concept. As St Thomas writes:

Whence, the similitude of the visible thing is that according to which the sight sees; and the similitude of the thing known, which is the intelligible species (species), is the form according to which the intellect knows (intelligit). But since the intellect is turned back on itself, according to this very reflexive action it knows both its simple act of knowing[4] and the species (species) that it knows (intelligit). And thus the species (species) is secondarily that which is known; but that which primarily is known is the thing of which the intelligible species is the similitude. And this is shown even from the opinion of the ancients, who posited that ‘Like is known by like.’ For they posited that the soul by means of the earth which was in it knew the earth which was outside it, and thus concerning other things. If therefore we accept the species (species) of the earth, in place of the earth, according to the doctrine of Aristotle which says, ‘The stone is not in the soul but the species (species) of the stone,’ it follows that the soul knows (cognoscit) by means of the intelligible species (species intelligibiles) the things which are outside the soul.[5]

This ‘species’ of St Thomas is similar to the ‘mental representation (noema)’ that Evagrius Pontikos discusses in the works that we will study in Volume II. Therefore let us spend some time on this matter.

Gilson has a detailed analysis of the stages of perception and intellection that is largely a digest of quotations and paraphrases of passages from various works of St Thomas, to which the reader is referred for a detailed analysis.[6] We will simply point out the most important aspects of St Thomas’ doctrine. It should be remarked that this is a very difficult field and that each interpreter of St Thomas has his own opinion what St Thomas really means.

The problem that is being addressed is how we know an object. In the case of the sense-perception of a sensible object, the problem is this: surely the object itself does not enter our mind. Nor, nowadays, do we want to say that the soul knows carbon because of the carbon that is in the soul itself. The sense organ is modified—usually, as here, sight is taken to be the sense in question, so we should assume the eye. This is the primary sense-perception: a modification of the cells in the retina of the eye. This primary sense-perception is of a particular object, not of a concept: we see a certain man, Tom, not ‘man’ taken to be a concept of man; and it is a similitude of Tom that impresses itself upon the cells in the retina of our eye, not Tom himself and not the concept of ‘man’. This primary visual perception of Tom is integrated by the common sense with the other primary sense-perceptions of Tom, received by means of the other sense organs, into an integrated sense-perception of ‘Tom’. The ‘phantasm’—this is simply the perceptual image—of the specific man, Tom, is the result. This is what is stored in the fantasy.

This ‘phantasm’ is the sensible species to which St Thomas is referring.

What St Thomas is saying is that in the case of a sensible object, what we perceive is the sensible object itself, by means of the similitude which we receive into our eye in the way just described, which similitude is integrated into a sensible species or phantasm by the common sense. This sensible species or phantasm is concrete. There is no question at this level, which is the level of the sensitive soul which depends intrinsically on the body, of a cognition of a universal, or objective concept, ‘man’. We merely have a sense-perception of ‘Tom’, a specific man. We are here at the level of concrete sense-perceptions. It is at this level that sense-perceptions are stored in the fantasy, at this level that the particular judgement or estimative power works in man and in animals, at this level that the memorative power works in man and in animals.

This notion of St Thomas of the sensible species or phantasm as a concrete sense-perception is exactly equivalent to Evagrius Pontikos’ concept of the ‘mental representation (noema)’ as applied to the perception of an object of sense, and the one concept can be taken to explain the other. The only difference is that Evagrius Pontikos has a simpler model of sense-perception without all the stages and faculties that St Thomas following Aristotle posits: there is no common sense in Evagrius, at least not in any obvious way, and apart from a few remarks in the Kephalaia Gnostica,[7] Evagrius does not discuss in the detail of St Thomas the actual mechanism of sense-perception.

The next stage is the stage of intellection, of grasping the universal, or objective concept, ‘man’ that is instantiated by ‘Tom’, the particular man standing in front of me and whom I see. Here, St Thomas’ doctrine is difficult to grasp.

At the stage of intellection, the problem for St Thomas is to identify just what is known by the mind and how. As we have seen, he is adamant that what naturally can be known by the mind in this life after the Fall of Adam depends strictly on sense-perception. Hence only those intelligible things that relate to objects of sense can, in St Thomas’ view, naturally be known by man in this life, apart from such principles as the law of the excluded middle and the law of cause and effect, which by intuition are known by the mind directly. The rest of the things that a man knows, he knows by reason—ratiocination on the model of Aristotelian syllogistic, even practical syllogistic—operating on concepts that the man has abstracted from the sense-perceptions of objects.

But, St Thomas wants to say, those intelligible things that we can know on the basis of sense-perception are not the sensible species or perceptual similitudes or phantasms of objects that we receive when we perceive an object of sense and that constitute the data of sense-perception as integrated by the common sense. Something more is involved than sense-perception. For knowledge is of universals or concepts, of the abstract properties of sensible objects, which abstract properties constitute the essences of the sensible objects.

These abstract properties are neither conventional (as when we say that ‘man’ is a concept defined by social convention) nor subjective (as when we say that ‘man’ is a subjective idea that depends on each person’s individual judgement), but objectively real (the concept ‘man’ is an objective fact), although not existing independently of the objects themselves (there is no autonomous Platonic form ‘man’ separate from individual men such as ‘Tom’). Moreover, St Thomas has asserted, man does not have innate species or ideas; hence, the abstract properties cannot arise from within him. Moreover, these abstract properties are not concrete sense-perceptions. Moreover, these abstract properties are cognized by the distinctly human part of the soul, the mind or intellect, which is at all not dependent on the body but which uses the data of sense-perception—the sensible species or phantasms of which we have just described the formation—as the basis for the intellection of these properties. This complex of conditions creates a demand on St Thomas’ theory of cognition: how the intellect knows the universal, or objective concept, ‘man’ that is instantiated by ‘Tom’, of whom the mind has only a concrete sense-perception or phantasm.

St Thomas solves his problem by asserting that the intellect knows universals or concepts but only on the basis of their abstraction from sense-perception. The intellect knows the universal, or objective concept—in St Thomas knowing is completely different from perceiving—by means of intelligible species which it abstracts from the sense-perception. This intelligible species is analogous to the sensible species by which in primary sense-perception an object of sense is perceived. St Thomas’ analogy is very important for an understanding of what he means.

When we perceive Tom, Tom himself does not enter our eye and our mind: the sensible species of Tom—the sense-perception of Tom, the phantasm of Tom—enters our mind. This is a similitude of Tom, not Tom himself. Similarly, when the intellect cognizes—understands—the universal, or objective concept, ‘man’, it does not receive the universal, or objective concept, ‘man’ into itself. What the intellect does receive into itself is the intelligible species of the universal, or objective concept, ‘man’: an abstract image of the universal, or objective concept, ‘man’. Hence, in St Thomas, the intelligible species by which we know the universal, or objective concept, is defined on an analogy with the visual similitude that we in sense-perception have of an object of sense.

This intelligible species is similar to our modern notion of a concept. For St Thomas means by ‘intelligible species’ the subjective concept that I have in my mind by which I know the universal, or objective concept, which is common to Tom, Dick and Harry: the quality of being a man.

We have already addressed the formation of the sense-perception. The problem now is the process of abstraction: how the human passes from the concrete sense-perception to the subjective concept—from the concrete sense-perception of Tom to the intelligible species, or subjective concept, of the universal, or objective concept, ‘man’.

We have a concrete sense-perception of Tom: this is the phantasm. Now, St Thomas says, our active intellect shines as a light on that phantasm of Tom and actively abstracts the universal, or objective concept, ‘man’ from the phantasm. However, in actuality the active intellect abstracts the intelligible species ‘man’ from the concrete sense-perception or phantasm of Tom. This intelligible species ‘man’ is the subjective concept that is the intelligible similitude or abstract image of the universal, or objective concept, ‘man’ instantiated by Tom. The intellect then places that intelligible species ‘man’ into our ‘possible intellect’. The active intellect and the possible intellect can be construed simply to be two functions of the human intellect logically required by St Thomas’ analysis of the act of knowing a thing. That is, in order for us to understand St Thomas without being distracted by mysterious faculties of the human intellect such as the active intellect and the possible intellect, let us simply consider these faculties to be things that the human intellect does: the intellect of man shines an intellectual light on the concrete sense-perception of Tom, abstracts the subjective concept ‘man’ that is an abstract image of the objective concept ‘man’ and then retains that subjective concept.

When we stated above that the mind received the universal, or objective concept, ‘man’ by means the intelligible species, we meant that the active intellect illumined the phantasm of Tom and then actively abstracted the intelligible species ‘man’ related to the universal, or objective concept, ‘man’ from that phantasm of Tom, and then retained that intelligible species, ‘man’.

It should be understood that the light that the active intellect shines on the phantasm of Tom is a natural, created light. It is precisely the light of the human mind that, when he was dismissing St Augustine’s psychology, St Thomas stated to be a participation in the divine light.[8] However, this participation by no means makes the natural, created light of the mind to be any more than similar to the light of God.

It should be remarked that Fr Copleston has a somewhat more refined analysis of the relation of the active to the possible intellect in the process of abstraction:

The active intellect then abstracts the universal element by itself, producing in the passive [= possible] intellect the species impressa. The reaction of the passive intellect to the determination by the active intellect is the verbum mentis (species expressa), the [subjective] universal concept in the full sense.[9]

The Thomist understanding of the intelligible species is very similar to Evagrius Pontikos’ doctrine of the mental representation (noema) related to an intelligible reality. In both cases there is an explicit analogy with the act of visual perception. In both cases, there is an objective character to the intelligible species or mental representation (noema) related to the intelligible reality. The difference, of course, is that on the basis of his Aristotelian realism St Thomas explicitly limits himself to the universal, or objective concept, as instantiated in concrete objects of sense, whereas Evagrius goes on, following a more Platonic metaphysics, to develop a doctrine of mental representations (noemata) related to intelligible realities that are not necessarily instantiated in objects of sense. Hence, in Evagrius there is no doctrine of the abstraction of the mental representation of an intelligible from the sense impression of an object. It would be a misreading of Evagrius to consider that this is what he has in mind in second natural contemplation when he indicates that the sensible object must be present for the (imperfect) mind to be able to cognize the intelligible reason (logos) of the sensible object. In Evagrius, the mental representation of the reason (logos) of the object is cognized intuitively with a spiritual faculty of the mind, one that St Thomas Aquinas does not recognize to exist. This spiritual faculty of the mind is similar to the ‘intelligentia’ of St Augustine. Moreover, in Evagrius, in contemplation, the mental representation (noema) of the intelligible reality alters (‘imprints’) the mind (nous) so as to transmit gnosis, intuitive spiritual knowledge, to it.[10]

According to Gilson, St Augustine has a concept of the ‘notion (notio)’ which is imprinted on the mind by the eternal reasons which exist in the Mind of God.[11] While according to Gilson’s interpretation, the content of the ‘notion (notio)’ is not a concept, it seems to us to be very close to Evagrius’ idea of the mental representation (noema) of an intelligible reality. For according to Gilson, who quotes St Augustine, the notion (notio) of ‘beatitude’ impressed on the mind is that according to which we say of ourselves that we desire beatitude. Psychologically, this seems possible only if the notion (notio) of beatitude in some sense gives us an intelligible foretaste of beatitude, which would be the same as the Evagrian notion of the mental representation (noema) of an intelligible reality which imprints the mind, especially in contemplation. St Augustine’s very verb, ‘impressed’, corresponds to Evagrius’ ‘imprint (tupono)’. According to Gilson,[12] concerning the impressing by the divine ideas on the mind, St Augustine uses the same image of the seal in the wax that Evagrius Pontikos uses for the mental representation (noema). These parallels make us wonder if there is a common source. However, Evagrius has no doctrine of the dual role of the reasons (logoi) in natural, common perception or cognition, and in mystical cognition, only a doctrine of the role of the reasons (logoi) in mystical cognition, that is to say, in contemplation.[13]

To return to St Thomas, St Thomas now goes on, with remarkable introspective insight, to comment that our intellect can turn back on itself in a reflexive act of cognition. By means of this reflexive act, the intellect knows both its own simple act of knowing and the intelligible species that it knows. Thus, in the first instance, by means of the intelligible species of the universal, or objective concept, ‘man’, the intellect knows the universal, or objective concept, ‘man’ that is instantiated by Tom, Dick or Harry. In the second instance, by a reflexive act of cognition the intellect knows both that it knows and the actual intelligible species, or subjective concept, ‘man’ that relates to the universal, or objective concept, ‘man’. However, St Thomas says, what is known primarily is the ‘thing of which the intelligible species is the similitude’ and what is known secondarily is the intelligible species, ‘man’. Here, there is a problem of interpretation. This ‘thing of which the intelligible species is the similitude’: is this the concrete object, ‘Tom’ or is it the universal, or objective concept, ‘man’ instantiated by Tom? We think that the evidence is that it is the universal, or objective concept, ‘man’. For knowledge is of universals. We do not think that it would make sense to say that what is known primarily is Tom, Dick or Harry taken as an individual, since what is in issue here is not sense-perception, which certainly is of Tom, Dick or Harry and not of the universal, but intellectual knowledge, which is of universals or concepts or propositions.[14] It is well to recall that in St Thomas’ system the concept ‘man’ is neither conventional nor subjective, but objective, although there is no Platonic form ‘man’ existing apart from individual men: Tom is a man, not conventionally, not subjectively, but because that is the structure of reality.

It is worth remarking on Aristotle’s own view. According to On the Soul,[15] in the reflexive act of cognition, the mind (nous) is able to cognize ‘itself’. This seems rather more substantial than a mere cognition of the act itself of cognition. Aristotle continues with a difficult but interesting discussion of the knowability of the mind (nous) by the mind (nous) itself.[16] However, we learn from Fr Copleston that St Thomas rejected the notion that the soul could have an immediate intuitive cognition of itself.[17]

St Thomas then establishes that we can cognize, or actively understand, only one thing at a time, whereas we can know many things simultaneously.[18] This is important, for it agrees with Evagrius Pontikos’ assessment in Chapter 24 of On the Thoughts.[19]

St Thomas establishes that the intellect knows the universal directly, and the particular object only indirectly.[20] That is, the intellect knows the universal, or objective concept, ‘man’ directly and Tom only indirectly. This is very important for our understanding of St Thomas’ doctrine of the nature of human knowledge. St Thomas says this:

Our intellect is not able directly and primarily to know the particular in material things. The reason for this is that the principle of particularity in material things is the individual matter; however, as has been said above,[21] our intellect cognizes (intelligit) by abstracting the intelligible species from matter of this sort. What is abstracted from individual matter, however, is the universal [‘man’]. Whence, our intellect directly cognizes only universals. Indirectly, however, and after a fashion, by a certain reflexive movement (reflexionem) it can cognize the particular [‘Tom’]. As has been said above,[22] even after it has abstracted the intelligible species [‘man’, ‘horse’, etc.], the intellect is not able to cognize in act according to them, unless it turns itself to the phantasms [sense-perceptions or recollections of sense-perceptions of ‘Tom’, ‘Black Beauty’, etc.], in which it knows the intelligible species [‘man’, ‘horse’, etc.], as is said in III De Anima [by Aristotle]. Therefore, the intellect thus directly cognizes the universal itself [‘man’] by means of the intelligible species [‘man’]. Indirectly, however, it cognizes the particulars [‘Tom’, ‘Dick’ and ‘Harry’] of which are the phantasms. And in this way it forms the proposition: ‘Socrates is a man’.[23]

In reading this article it is well to recall that the province of the intellect is knowledge, not sense-perception.

We see here that the intellect directly knows the universal, or objective concept, ‘man’ by means of the intelligible species ‘man’ that it abstracts from the phantasm of the concrete object, Tom. The intellect only secondarily, by a reflexive act, knows Tom himself.

Moreover, St Thomas says in the last part of the body of the article, when a person wishes to think about the concept ‘man’, which he has already abstracted from concrete sense-perceptions of Tom, Dick or Harry and retained, he must nonetheless return to recollections of sense-perceptions—phantasms—of concrete men whom he has once perceived: Tom, Dick or Harry. What St Thomas means is that we cannot reason absolutely abstractly; we must have recourse to the phantasms by which we came to know the abstract concepts about which we are reasoning. As St Thomas himself says, arguments are elucidated by examples. This is true, curiously enough, even in pure mathematics.

Summarizing, St Thomas then repeats that the intellect directly knows the universal, or objective concept, ‘man’ and indirectly the particular, or concrete object, ‘Tom’. Moreover, St Thomas says, this is how the intellect comes to form the proposition: ‘Tom is a man.’

For St Thomas, knowledge in this life is propositional. The knowledge that the intellect has is the proposition ‘Tom is a man.’ Mystical or intuitive knowledge can only come about supernaturally. In the Thomist system there is a very sharp disjunction between natural human knowledge, which is a rational knowledge based on the manipulation of propositions based on concepts in the way just described, and supernatural mystical knowledge. In the doctrine of the Philokalia, and even in St Augustine, there is no such sharp disjunction: man retains the natural capacity intuitively to cognize intelligible realities both in mystical experience and in ordinary experience. Of course, neither St Augustine nor the Philokalia deny the necessity of grace in mystical experience.

The Thomist doctrine of the abstraction of the concept from the data of sense-perception had its effect on the interpretation of St Augustine’s own doctrine. For recall that in St Augustine’s theory of cognition the divine light illuminates the intellect or intelligence, which is higher than the reason. But a question arises that Gilson discusses as follows:

It follows from that, that St Augustine deliberately removes from the divine illumination all knowledge that our intellect (intellect) might abstract from the sensible, and even that he denies that our intellect (intellect) might be able to have the sensible for object; only the reason (raison) deals with the sensible; as for the intellect (intellect), uniquely occupied with the intelligible order, it has nothing to abstract from material things and the divine light that it receives is not given to it for that purpose. But if the illumination does not abstract [in the Aristotelian or Thomist sense just discussed by us above] what does it do?

One can say without any exaggeration that this question has exercised the sagacity of many generations of historians. The most apparent datum of the problem is the absence of data. Augustine himself tells us neither how the intellect operates nor what it does. Certain persons simply observe this serious lacuna. Others, although admitting that St Augustine has said nothing of the sort, force themselves to fill the gap by lending to Augustinian thought an abstractive activity…; why, indeed, would it not be legitimate to complete his doctrine on this important point by introducing that which it lacks in a gap predestined to receive it? Notwithstanding, it seems to us that there might be a hypothesis more simple to envisage, which is that on this point there is no lacuna in the system of St Augustine, it being understood that one looks at it from his own point of view and that one does not argue in the name of principles which he never himself accepted. In reality, in Augustine there is no problem of the Umsetzung [application] of the sensible to the intelligible; if he did not resolve it, it is because he did not have to pose it, and to wish that he had resolved it is not to fill a lacuna in his doctrine but to transform that doctrine into another…[24]

To continue, we remarked that post-mediæval modern philosophy is largely a reaction against mediæval philosophy. One place where this is very true is in the rejection by and large by modern philosophy of the notion of the fixed essence of a thing. This essence of a thing is the universal, or objective concept, instantiated by the individual object, in the example that we have been using, ‘man’ instantiated by ‘Tom’. For what St Thomas is describing is the way he understands the mind to grasp the objective and real essence of Tom—that he is a ‘man’. And what David Hume rejected, apart from the very existence of mind as an autonomous substance or even power of an autonomous soul, is the notion that there are such objectively real essences that are grasped by the mind in the manner delineated by St Thomas. As A. MacIntyre remarks in his article ‘Essence and Existence’ in the Encyclopedia of Philosophy:

The mistake which Hobbes and Locke ascribed to Aristotelianism was that of confusing the meaning of an expression with the nature of the object which the expression characterizes. In the empiricist tradition this separation of questions of meaning from questions of characterization continued to be influential. One consequence is that the concept of the real essence is dropped altogether. Another is that philosophy itself becomes defined as the study of meaning, as a linguistic enquiry.…[25]

Much of modern philosophy is influenced by empiricism on this point.

It might be recalled that in Hume, the concept is due to the association or combination of ‘ideas’, which are the interior images of sense-perceptions, passions or emotions. This is a completely different approach than that of the authors we have been studying, St Thomas, Evagrius Pontikos and St Augustine. For these authors recognize the existence of both the essence of the material object—according to each author’s theory surely—and the domain of the intelligible which cannot be reduced merely to the association or combination of interior images of sense-perceptions, passions and emotions.

It is noteworthy that Hume also threw a very sceptical regard on the notion of cause and effect, which is precisely one of the ‘first principles’ that St Thomas judged to be intuitively evident to every man once he had understood the definitions of the terms. Modern philosophy can be seen as a reaction against this aspect of mediæval philosophy too. This reaction reaches its apogee in the philosophical tendencies expressed in and around quantum mechanics, where time’s arrow is uncertain, causal relations are uncertain, all things are uncertain and contradictories exist at one and the same time: all these positions involve denials of first principles to which St Thomas judged the human intellect incapable of refusing assent once it understood the terms. Although St Thomas did not spend any time on geometry, the same denial of intuitive first principles is to be found in the special and general theories of relativity, this time geometrically. Moreover, the physical interpretation of the two theories of relativity involves propositions such as the variability of time which also might be thought to deny principles which St Thomas would have considered intuitively evident. An interesting question would be this: have St Thomas’ views on the intuitive validity of the first principles been superseded, or will there come new theories in physics, which theories themselves will be more ‘intuitive’ in the Thomist sense, which theories will incorporate the data which are accounted for by the modern ‘counter-intuitive’ theories? For no theory in physics is eternally true.

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[1] ST Ia, 85.

[2] ST Ia, 85, 1.

[3] ST Ia, 85, 2.

[4] Intelligere—see ST Ia IIae, 8, 2.

[5] ST Ia, 85, 2.

[6] Gilson E, pp. 244–56.

[7] See Section 6 of Chapter III, ‘The Evagrian Anthropology’.

[8] ST Ia, 84, 5.

[9] Copleston Volume II, pp. 389–90.

[10] See Chapter III, above; also the Digression on the Evagrian doctrine of contemplation and the Commentary on On the Thoughts, Chapters 38–43 in Volume II.

[11] Ibid. p. 122.

[12] Ibid. p. 125.

[13] Cf. Gilson, ibid. p. 126.

[14] This agrees with ST Ia, 86, 1, quoted immediately below.

[15] Arist–Soul III, 4, 429^b6–10.

[16] Ibid. ll. 429^b11 ff.

[17] For a discussion by a non-Thomist Aristotelian scholar of the nature of the mind (nous) in Aristotle and of its capacities according to Aristotle for intuitive apprehension beyond such first principles as the law of the excluded middle, see the commentary on the Nicomachean Ethics by H. H. Joachim (Joachim pp. 288–91).

[18] ST Ia, 85, 4.

[19] See Volume II.

[20] ST Ia, 86, 1.

[21] ST Ia, 85, 1.

[22] ST Ia, 84, 7.

[23] Ibid.

[24] Ibid. p. 115.

[25] Encyclopedia Volume 3, p. 59.