Sunday, 10 November 2013

Question 87 – How our Intellect Knows Itself and What Exists Within it.

Why this Question Matters

It’s clear that we have an understanding of ourselves understanding something. But how does this type of understanding come about and what exactly is it an understanding of? When we’re not thinking, but staring vacantly into the middle distance, what do we know of ourselves?

This question might be seen as a coda to Ia.q85, considering the intellective cognition of intellective cognition.

The Thread of the Argument

A1: Aquinas’s first task is to enquire into whether the intellect understands itself through its own essence. Our first task is, perhaps, to understand what this question actually means!

We’ve seen that the intellect understands a material thing by a process of abstracting universal intelligible species from phantasms of the thing constructed by the sensory powers. The problem is that if the intellect is to understand itself, then it has to understand something that is immaterial. So we recall that the human intellect is an immaterial substance that is in potentiality to receive intelligible species. The actuality of its understanding (that is, when it actually understands something) is the very act of moving from potentiality to actuality in the reception of an intelligible species. So really all that the intellect can work with in understanding itself is its essence (in other words, what it is fundamentally, defined by its form) or its potentiality (that is, its ability to understand things) or its actuality (that is, what it understands in accumulating accidental intelligible forms). Which one is it?

The key to Aquinas’s approach to this question is the assertion that a substance bears the same relationship to being intelligible through its essence that it bears to being actual through its essence. In the case of material things this principle is clear: we can only have cognition of something insofar as it is actual; that is, insofar as its form is actualized. Aquinas carries this principle over to the immaterial.

Next he goes runs through some exemplar essences. God’s essence is perfect actuality, perfectly intelligible in itself; therefore God has perfect intellective understanding of all things, including Himself, through His essence. Angels are a little bit further down the scale of being. They have cognition of themselves through their essences, but they do not understand everything thereby; cognition of things other than the angel himself is supplied through impressed intelligible species supplied directly by God at the creation of the angel. When we get down to the level of humans we realize that the potentiality of the passive intellect to receive intelligible species parallels the ability of prime matter to receive form. So, considered in its essence, the human intellect only has intellective understanding in potentiality. Applying the principle that was outlined above, we deduce that the human intellect can only be understood intellectively in its act; that is, as it is actually understanding something.  It is through its act that the human intellect understands itself, not through its essence.

Aquinas goes on to identify two ways in which we have cognition of intellect. The first way, which he calls a particular way, occurs when any particular individual perceives himself to be having an intellective understanding. This happens when the act of the mind is in a way present to the person having the cognition and is an experience and knowledge available individually to anybody. On the other hand, there is a more general way in which we understand the mind’s cognition that is obtained through lengthy and diligent enquiry. This is the way in which we understand what is actually going on in the act of understanding; to understand this we have to discern the nature of the soul, understanding the derivation of our intellect’s light from God’s truth.

The third objection, derived from Aristotle’s de anima, argues that in the understanding of immaterial things, the intellect and what is understood are the same. In other words, what is impressed on the passive intellect is the form of the thing understood, which just is the thing understood. Therefore the intellect must understand itself (being immaterial) though its own essence. One might at this point worry about infinite regress (the form of the intellect being impressed in the intellect as understanding itself) but Aquinas takes the line that Aristotle is being misunderstood in the objection. Aristotle’s dictum applies differently in those things that exist entirely without matter (separated substances like angels) to those forms that exist in matter (like the soul). For forms that exist in matter, the intelligible species that exists in the intellect is a likeness of the actual material thing through which it is understood and is not identical to it. The objection would stand if we were talking about angels having cognition of their own understanding.

A2: A very important part of being human is our ability to accumulate expertize. Through years of training one might become a concert pianist, or a mathematician, or a linguist, or simply a virtuous person. Expertize seems to be present in us as a sort of stable disposition; in the absence of trauma, the expert does not simply lose expertize overnight. This type of stable disposition Aquinas calls habitus which is often translated as “habit”, although one must be aware that the modern use of the word is somewhat different to that used by Aquinas. It is a very important concept that he will turn to throughout the summa. Here he asks about how we have cognition of the soul’s habits; is this cognition through their essence?

If one thinks about the ability (in a non-native French speaker) to speak French, then one might recognize a number of stages in the development of that skill (or habit). One would at least recognize a period when the language is being learned, perhaps a period when knowledge of the language was being cemented and a period in which the speaker has become habitually as good as a native speaker. In terms of moving between potentiality and actuality one would also recognize that the absolute beginner has a potentiality to learn the language that becomes an actuality as an ability to speak the language that is itself in turn a potentiality to be actually speaking the language right now.

So, as Aquinas says, a habit lies somewhere between being a pure potentiality (the ability to learn it) and a pure actuality (actually speaking it right now). But we recall from above (Ia.q87.a1) that nothing is understood unless it is actual; so a habit is only knowable insofar as it is actual. So we have two ways in which we have intellectual cognition of a habit. In the first way we have cognition of it as we are actually producing the act proper to the habit (actually speaking French right now). The second way parallels the second way in which we saw how the mind understands itself; though diligent enquiry into the way that habits work.

A3: The first two articles of this question have shown us that we have cognition of our intellect and of its habits by means of its acts rather than through essences. But there would seem to be problems with this conclusion: the object of cognition would seem to be an external thing understood in its quiddity, rather than the actual act by which we have cognition of it. Again, if there is cognition of something, and we have cognition of that act of cognition then we must also have cognition of this latter act and so on to infinity. Third, shouldn’t we really recognize that there’s something analogous to the common sensory power lurking behind the intellect; the things that is actually the “I” having the cognition of cognition?

Following the pattern used in the first article, Aquinas runs through the examples of the cognition of God and of the angels before considering the cognition of human beings. What he is concerned with here is the different ways in which we should understand that the first thing to be understood about an intellect is its act of intellective understanding. When we consider the intellect of human beings we recognize that there’s a sort of trinity of things going on in an act of cognition. First of all there is the act of cognition of the external object itself, but simultaneously there is cognition of the act of this first cognition. We’re not finished yet: in these two modes of cognition there is cognition of the intellect itself, because the intellect, brought to its fullest level of actuality, precisely is the act of intellectual understanding.

Aquinas points to a too narrow understanding of the object of the intellect as being the root of the problem with the first objection. The actual object of the intellect is being and truth; and it’s clear that the act of intellective understanding falls under these as object of cognition. The second objection falls by recognizing that we could have an infinite regress of acts of cognition, but it is a potential infinity rather than an actual infinity. In an act of cognition of an external thing, the two different things cognized (the external thing itself and the cognition of that thing) are different. A further reflection on the act of cognition, presumably initiated by the will, would be required for cognition of the act of cognition. This we can do until we have had enough, but we would get bored long before we reached infinity. Aquinas answers the third objection by pointing out that the parallel between the senses and the intellect fails because the senses involve the use of material organs; intellectual cognition is immaterial and therefore there is no need to posit something behind the intellect.

A4: What about acts of the will? Do we have an intellective understanding of these? After all, it would seem that the will lies outside the scope of objects of the intellect. Aquinas points out that an act of the will is an inclination that follows upon a form that has been understood. He uses three examples to illustrate the different modes in which inclinations can exist. The form corresponding to the weight of an object inclines that object to move in a certain direction in a gravitational field, and we say that this inclination is natural to it. The form corresponding to a bowl of ripe strawberries inclines the sentient appetite to make a beeline for the cream and a spoon; the sentient desire exists in the sentient faculty. Likewise the intellectual cognition that the strawberries appear to be rather unripe leads to an act of the will to put a bit of sugar on them; this inclination exists intelligibly. So Aquinas concludes, following Aristotle, that there is a mode in which we can consider the various inclinations to exist in their corresponding faculties. So the act of willing, existing in the intellect, can be perceived in two ways: in a perception of willing something in general; but also in a perception of the nature of what is being willed.

Handy Concepts

  • The intellect has cognition of itself through its act rather than through its essence. Likewise, we have intellectual cognition of our habitual abilities through their act.
  • Acts of the will exists in some sense in the intellect, as it is at the very least supplying the object of the will. As such, acts of the will are understood by the intellect.


  • Aquinas’s argument that we have cognition of the intellect only in act seems reasonable from the point of view of introspection. We are only aware of our intellects when they are having intellectual cognition. In those periods in which we empty our minds, in meditation perhaps, do we have cognition of our minds?
  • In the second article Aquinas does not explain in any detail the second way in which the mind has cognition of habits; he simply says that it is through diligent enquiry. The parallel with the first article suggests that this is a diligent enquiry into how habits work but one might also ask whether there is another aspect of introspection at work here. If I have an intellectual reflection on a memory of having spoken French yesterday should this be considered direct cognition of my habit of French? Or does it fit into the schema of Aquinas’s second type of cognition of habit? Perhaps my simple recollection and reflection is not sufficient to be considered cognition of the habit but rather has to be supported by further reasoning. For example, I can recall that I was speaking French yesterday, but I have to reason that this was the act of a habit (rather than divine intervention or inebriated inspiration) and that if I had the habit yesterday, then I probably have it today.
  • Aquinas’s answer to the third objection of the third article may be disappointing to those who wish to identify some sort of separate faculty of the soul that is the “I” behind the intellect. For Aquinas, the intellect is where the show stops (bearing in mind, of course, God acting as first mover of the agent intellect). The actuality of the intellect in the act of cognition is itself cognized by the intellect. Perhaps it would have been helpful for Aquinas to say more at this point on the very human activity of reflection. After all, we often think that it is this very ability to reflect on experience, in a way that unites all the faculties of the soul, which defines the “I”.

Sunday, 3 November 2013

Question 86 – What our Intellects know in Material Things

Why this Question Matters

After the rigours of Ia.q85, this question sweeps up a number of particular issues to do with the cognition of material things. In particular it covers the cognition of singulars, of the infinite, of contingent things and of future things. In many ways, the content of this question represents a drawing together of issues that have been presented in various places of this treatise.

The Thread of the Argument

A1: Aquinas has already argued that the active intellect abstracts the universal from the phantasms presented to it by the sentient powers, and that the resulting intelligible species are retained in the passive intellect. This means that the intellectual powers acting on their own do not have cognition of singular concrete individuals but only of their universal aspects. Here Aquinas raises this observation to the status of an article, summarizing the arguments made so far and addressing some particular objections. The major point to be made is not that we do not have cognition of singulars, but that our cognition of singulars is not by means of the intellect alone. The intellect and the sentient powers act together in the cognition of singulars, so that the intellect has direct cognition of universals but only an indirect cognition of singulars.

A2: Right back in Ia.q7.a4 we saw Aquinas talking about the infinite as existing. Now it is time to consider the infinite as object of cognition; so, can we have cognition of infinitely many things? Aquinas’s answer revolves around the difference between a potential infinity and an actual infinity. If you were to start counting sheep in an effort to get to sleep, you would start “one sheep, two sheep, three sheep…” potentially with no limit if the insomnia were particularly bad that evening. This is an example of a potential infinity; you can count things as far as you have time to do so without theoretical limit. But you will never be in the situation of having counted an infinite number of sheep; you never get to the point of having cognition of an actual infinity of sheep. This is Aquinas’s position: we can have cognition of an arbitrary number of things but we cannot have cognition of a completed infinity.

The first objection claims that we can have cognition of something infinite; that is, God. Aquinas answers that there’s a subtle equivocation of language here. We would have an infinite material thing if there were no formal termination to its matter; that is, it would just go on for ever and ever. However, when we talk of God being infinite, we have to recall that His form has no connection with matter at all and therefore could not be terminated by an extent of matter. God’s form is per se infinite, rather than in reference to any matter. So a material infinite, if it existed, could not be known as the form is never terminated, but we can know something of the infinite God insofar as we grasp something of His form. Of course, our minds are limited in the extent to which we can grasp God’s form: in this life we can only grasp it by inference from the created order; in the next life by direct illumination by the divine essence. Still, by neither means can we comprehend that form (Ia.q12.a7).

A3: This third article is a strange little affair: Aquinas asks whether we can have cognition of contingent things. That is, can we have cognition of things that are able to be and not to be? As pretty much everything we perceive in the material world is contingent one has to ask why how this question could ever arise! The point is that, when we have cognition of things, we abstract the universal from the particular and the universal is not contingent in the same way that the object of cognition is. Now Aquinas does not take a Platonic view of form: forms do not exist in some third realm but exist only as instantiated. Still, the question has some force as this vase could go out of existence but the form of the vase could still exist (but not in a material mode) in some mind that had previous perception of it, or in a different exemplar of the vase produced by the same potter.

Aquinas argues that the sensory power has direct cognition of contingent things; we recall that the phantasm of an object of perception is still a phantasm of a particular material thing. The intellect only has an indirect cognition of a singular through the interaction of its universal knowledge of the thing with the sensory power’s individual knowledge of the thing. So our knowledge of a thing is made up of a complex of contingent stuff corresponding to the perception of the sensory powers together with cognition of universal necessary aspects of the thing in the intellect.

A4: To ask whether we can have cognition of future things, as this article does, is clearly naïve, as future things have not yet happened and therefore cannot be subject to the process of abstraction from phantasms formed from an object being perceived by the senses. However we might reasonably argue that we know that the sun is going to rise tomorrow; so the future can obviously be known in some sense. The universal that we abstract from the particular is abstracted from time and may therefore contribute in some way to knowledge of future things.

Aquinas recognises the connection with the third article concerning our knowledge of the contingent. Future things, after all, are contingent. He makes the key distinction between knowing future things in themselves and in their causes. Cognition of future things in themselves (that is, in their concrete existence) is known only to God who has an eternal intuitive vision of all time (Ia.q14.a13). However, we can know future things in their causes; through our scientific knowledge we know, to a certain extent, how the material world works and can therefore make reliable predictions about certain things (such as the sun rising tomorrow morning).

Handy Concepts

  • Our cognition of singulars occurs by means of the intellect returning to the phantasms made available to it by the sentient powers.
  • We have cognition of the potentially infinite but not of the actually infinite.
  • Our cognition of contingent things occurs by a combination of the universal retained by the intellect and the particular retained by the sentient powers.
  • We can know future things in their causes but not in themselves.


  • Aquinas’s teaching that we do not have purely intellectual cognition of singulars is often a stumbling block for those coming anew to his theory of mind. Perhaps the aspect for newcomers to concentrate on is that Aquinas has a very precise theory about how the different parts of our cognitive powers work together; perhaps our modern notion of intellect glosses over some of the distinctions between powers that Aquinas considers essential. So, it is not that we do not have cognition of singulars, but that we have cognition of singulars in a way that involves more than just the intellect. The intellect is a very particular part of our cognitive apparatus.
  • Perhaps Aquinas is rather optimistic in the second article in suggesting that we can have cognition of a potential infinity. My experience these days is that if I learn something new, something old falls out of the other side of my head.

Question 85 – The Mode and Order of Intellective Understanding.

Why this Question Matters

Having warmed up on the lower slopes of Ia.q84, it is time to ascend the Mount Everest that is Ia.q85. Aquinas has assembled the components of his theory of mind. If we were to carve a simple straight line through the theory, ignoring complications like memory then it would look something like this. The external sensory powers receive sensible species corresponding to their proper objects. The internal sensory powers assemble the data received by the external sensory powers in the expressed sensory species known as the phantasm. The active power of the intellect illuminates the phantasm and in doing so abstracts the universal intelligible species from it. The intelligible species is then impressed upon the passive power of the intellect. The expressed species of the passive intellect provides the conceptual material with which the process of intellectual reasoning begins.

It is now time for Aquinas to throw the strongest objections that can be found at his theory and to defend his theses against them. The first three articles in particular are intellectual tours de force. Whilst pondering these articles the reader might wish to consider that the objection presented to Aquinas’s theory should also be presented mutatis mutandis to any theory of mind. After all, one of the most remarkable things about human existence is that there is a subject, an “I”, experiencing intellectual cognition of external things and able to reflect on these experiences as a cognitive act in itself. How do things that exist outside of my mind come to exist inside my mind so as to enable me to understand them? Any theory of mind worthy to present itself in the public forum should be prepared to answer the type of objections presented here.

The Thread of the Argument

A1: The first article focusses on the abstraction of intelligible species from phantasms by the active intellect. The structure of this question makes it clear that Aquinas is focussed on a number of weighty objections rather than on a new exposition of the basic theory. His main answer merely differentiates between the three levels of cognitive power that one can find in sensory cognition, in angelic intellection and in human understanding. The object of a sensory power is a form as it exists in a material object; so sensory powers only have cognition of individual concrete particulars. Angelic intellection is through immaterial species that are connatural to them (Ia.q55.a2) and therefore their intellection of material forms is in themselves and in God, without any need for abstraction from the material. Human intellection stands in the middle of these: the human intellect is immaterial and therefore for a human to have an immaterial cognition of something that is material necessarily has to involve the abstraction of form. The only candidate for the object of such abstraction is the phantasm produced by the sentient powers of the soul.

The first objection argues that, if the intellect were to abstract the intelligible from phantasms, rather than directly from the material object, then it would not understand the material object but rather a representation of the object. Aquinas counters by making a distinction between two modes of abstraction that will enable him to identify where error might happen in the process of abstraction. The first method of abstraction involves abstracting things in relation one to another (he calls it the mode of composition and division); this mode allows for error when we abstract relationships that are not abstracted in reality. The second mode of abstraction (the mode of simple and absolute consideration) involves pulling apart things that are not abstracted in reality and considering them in absolute rather than relational terms. For example, we can consider the colour of an apple in isolation from the fact that it is the colour of this apple. This form of abstraction involves no error whereas the first form of abstraction, which might lead us to say for example “the colour of the apple is separated from the apple”, can involve error.

Aquinas claims that the abstraction of intelligible species from a phantasm involves the second mode of abstraction: considering the nature of the material object which is being abstracted from, rather than any individuating principles that remain represented in the phantasm. Error can occur in abstraction when it is done in such a way as to misrepresent reality; but it does not occur simply because the mode of existence of forms of material objects in the soul is different from the mode of existence of those forms in reality. The forms of material things existing in the soul are the forms of those material things and therefore provide us with a sound basis for intellections.

The second objection observes that material objects are, by their very definition, material; since the process of abstraction from phantasms involves abstracting the universal from the particular, taking form away from matter, then this would seem to mean that we cannot actually understand material things as we’ve removed part of their very definition from them. Aquinas replies to this distinguishing between common matter and designated matter. The former is matter considered in general and the latter is matter considered in particular; the example that Aquinas gives distinguishes between flesh and bone and this flesh and these bones. When perceiving, for example, a human being, the process of abstraction from phantasms involves abstraction from the particular designate matter of this flesh and these bones but not from the common matter of flesh and bone. We understand material objects in the fact of their materiality but abstracted from the particular designate matter out of which they are formed.

Aquinas takes this opportunity to go further: in the case of mathematical species we can abstract even further, removing consideration of many sensible qualities. Mathematical entities are abstracted considering them only with respect to quantity, which Aquinas calls the level of common intelligible matter. They are thought of in isolation from this or that substance, that is they are abstracted from what is called individual intelligible matter. When we go beyond the mathematical, considering things like being, one, potentiality and actuality, then we go even beyond this form of abstraction considering such types of things completely in isolation from matter.

The third objection turns to the idea that phantasms could act on the passive intellect in the same way that sensible qualities act on the corresponding organ of sense. There seems to be no need for the active intellect and for a process of abstraction if the phantasms do all the work. Aquinas identifies the key problem with this idea as the fact that phantasms exist in the material bodies that are the sense organs and that the passive intellect is purely immaterial. As the material cannot directly affect the purely immaterial, there must be an immaterial active principle (the active intellect) responsible for getting the appropriate information from the phantasms to the passive intellect. Aquinas builds on this answer in the replies to the final two objections, describing further the action of the active intellect. The active power of the active intellect illuminates the phantasms rendering them suitable for the abstraction of intelligible species by joining the power of the intellect to the powers of the sentient soul; the process of abstraction extracts the natures of the species of what is being considered without their individuating conditions and impresses them on the passive intellect. The intellect understands the object of perception by turning back to the phantasms in the context of having abstracted the quiddity of the object from the phantasms.

A2: The active intellect abstracts the quiddity of the object of cognition from phantasms presented to it by the sensory powers. The intelligible species extracted by this process of abstraction are then impressed upon the passive intellect. But if what is present in the passive intellect are intelligible species and if it is these only that the passive intellect has for the understanding of things, does this not mean that it is the intelligible species that are understood rather than the object of cognition from which these intelligible species originally arose? The arguments of the three objections are all related to this type of reasoning; and this objection is itself a variant of the objections of the first article as related to the abstraction of intelligible species from phantasms rather than directly from the object of perception. The counter position that Aquinas wishes to argue for is well laid out in the sed contra: just as the sensible species are that by which the sensory powers sense, so the intelligible species are that by which the intellectual powers understand the objects of cognition. In both cases, the respective species are instruments. Sensitive species are not sensed, intelligible species are not understood; sensitive species are that by which some external object is sensed, intelligible species are that by which some external object is understood.

Aquinas advances two arguments against the position implied by the objections and gives an argument in favour of his position. In the first place, if the knowledge we have of things was purely of species that exist in the soul, then this would apply to things about which we have scientific knowledge; to Aquinas, this seems obviously wrong as scientific knowledge is about the external world. The second argument is that such a position must inevitably lapse into a radical subjectivism: “whatever seems to be the case is true”. If knowledge simply is of what is inside our heads, then whatever is inside our heads is all that gives rise to knowledge.

In favour of his own position, Aquinas takes the lead from Aristotle’s Metaphysics 9. We can think of two actions: one which remains within the agent (like thinking) and one which passes into a patient (like cutting a log). Both actions stem from some form, and in both cases the form must possess some sort of likeness to the object of the action. The form of cutting is a form of cutting that log over there; the form of thinking is the form of thinking about that log over there. So the form, that is the intelligible species, of the log that we are thinking about, is precisely the form of the log and the intelligible species is a sort of likeness of the log by which we think about the log. We can, of course, reflect upon our own act of intellectual understanding. In doing so, we will understand both our act of understanding and the intelligible species by which we do that understanding of our understanding! It is in this secondary sense that we can say that intelligible species can be the direct object of intellection; but still, the primary sense of intellectual understanding is of the object for which the intelligible species provide a likeness.

When we perceive a human being, their human-ness is apprehended in our intellects without individuating conditions; the intelligible species provide a likeness of the human-ness without there being a likeness of the individual.

The reply to the third objection introduces the important notion of an expressed species. When the sensory powers receive sense impressions from some external object, the object acts upon the organs of the sensory powers. The power of the imagination then forms an expressed species (the phantasm) from what has been impressed upon the sensory powers by the external object. The same sort of thing happens in the intellect. The passive intellect is acted upon by the impression of intelligible species. It then forms an expressed species which is called the concept or word. In this way the process of intellection comes to sort of terminus connecting with our linguistic reasoning processes. The concept may be expressed in language; the uttering of a sentence connecting words represents the intellect’s process of composition and division by which we reason about things.

A3: Aquinas has established that the intellect comes to understand the quiddity of things by means of the active intellect abstracting the universal from the phantasms presented to it by the sensory powers. The question that Aquinas wishes to address in this article is whether there is some sort of ordering of universality in the intellect. So, when we are looking at a human being, is the more universal notion of animal in some sense prior, or posterior to the notion of the universal human being?

Aquinas answer that when we think of sensory cognition, then certainly we have cognition of singulars before the intellect gets to work to give us cognition of universals. In this sense then, the cognition of what is less universal is prior to what is more universal. But when we consider the intellect as it moves from potentiality to actuality in its act of intellection, we realize that it moves from a state of incompleteness to a state of completeness the better we understand the object of cognition. The terminus of this act of intellection is complete scientific knowledge of the object of cognition; before we reach this state (if we do), our incomplete knowledge is still a bit murky in places. The indistinctness lies in our ability to first grasp a sort of universal whole, with all its parts considered integrally, without grasping the quiddity of those parts that make up the whole. Our grasp of the universal whole is less distinct but more universal than a grasp of the whole considered together with its parts. So, when we perceive something as an animal, without understanding that this animal is a rational animal, we grasp something more universal prior to coming to an understanding of a less general universal. In this sense, then, the more universal is prior in our intellects to the less universal.

In the reply to the first objection, Aquinas identifies two ways in which we can consider universals that might confuse us when considering universals in the context of cognition. In the first way the universal is considered alongside its intentionality; that is, together with the fact that a particular universal has a relationship to all the things from which it could be abstracted. The universal horse has a relation with all actual horses, for example. If we consider universals together with their intentionality, then the more universal should be considered posterior to the less universal. Since we grasp the intentionality of a universal by repeated acts of cognition, we arrive at the scope of the less universal’s intentionality sooner than for the more universal. If, one the other hand, we consider the universal as universal without any notion of intentionality, then in nature we find two possible orderings. In the generation of things, the more universal is prior to the less universal, so that animal comes about before human. On the other hand, in the ordering of perfection actuality is prior to potentiality and therefore the perfect is prior to the imperfect and the less general prior to the more general.

A4: Can we have an intellectual understanding of more than one thing at a time? It would seem that we must be able to: after all, if we’re to understand wholes that are made up of parts, and if we’re to be able to make comparisons between different things then we must be able to hold multiple things in our intellects simultaneously. Also, as the second objection puts it, there doesn’t really seem to be any good reason to deny it as a possibility.

Aquinas thinks differently. It’s impossible for a single intellect to be brought to actuality by more than one form simultaneously, just as something cannot simultaneously be informed with the form of an apple and the form of an orange. The intellect can have intellectual understanding of many things simultaneously provided they are grouped together under some single form. This even applies to God’s intellect: He has simultaneous intellectual knowledge of everything through the single form of His substance.

When we think of the parts of a whole, we can think indistinctly of the parts as they exist in the whole; so we think about the house and the bricks out of which it is built are grouped together in the background under the form of the house. If we think distinctly about the parts of the whole, then we lose immediate sight of the whole; if we think of a brick, we are not thinking of the house. Similarly, when we make a comparison between two things, we hold both of the things in the intellect under the form of a comparison; there’s a sort of whole composed of the two things, rather than the two things individually considered.

A5: Human intellectual understanding of things in the world is progressive; there is always a passing from potentiality to actuality involved. When we apprehend something, we apprehend it in stages one aspect at a time. So, in seeing Socrates in the distance we may very well go through a process rather like this: we firstly apprehend him as being a living being and very quickly after that recognize him as a human being. On seeing the components that make up his face, we recognize this human being to be Socrates. We notice that he is wearing a white robe and that he has leather sandals on his feet. This process involves the apprehension of various quiddities together with a successive composition of and division between them. For example, when we apprehend that Socrates is wearing a robe and we apprehend the robe’s whiteness we compose the notions of Socrates, of white, and of robe to arrive at the conclusion that Socrates is wearing a white robe. Similarly in recognizing Socrates by seeing his face we compose the notion of human being with our notion of Socrates but divide off the notion of human being from everybody else that we recognize but Socrates. Thus, in human intellection a process of composition and division of concepts is a key part.

This process of composition and division that humans have to go through is in marked contrast to intellectual understanding in the angels and in God. The latter do not have to gather their intellectual understanding of things from the senses and therefore do not have to put concepts together in the same way. The intellectual understanding of angels arises from forms connatural to them and infused at their creation; that of God is His very substance.

The third objection argues that in the real world things simply are the way they are: the ball simply is white. There are no processes of composition and division in the world of things that corresponds to the intellect’s processes of composition and division. Aquinas concedes that the likeness of an external object is received in the intellect in a mode of being that is different from the mode of being of the original thing. So, it not surprising that even though there may be in the external object something that corresponds to the intellect’s composing and dividing, it is not present in the object in the same way as it is present in the intellect. However, we can still identify the composition of form and matter in the external object with the composition of a universal whole with its part in the intellect and the composition of subject and accident in the external object with the composition that corresponds to predication in the intellect. So there is a correspondence between the sorts of composites that exist in the external world with those that exist in the intellect. This correspondence is what enables us to maintain that the likeness as it exists in the intellect is faithful to the external object.

A6: In his de anima chapter 3, Aristotle makes the astonishing claim that intellective understanding is always correct. Since it is manifestly clear that we can be mistaken about things that our intellect considers, we must enquire into what Aristotle, and Aquinas following him, means.

Aquinas argues that we should observe the parallel with the sentient powers. The external senses, when they are not impeded, are never mistaken about their proper object. The sensory powers can still make mistakes, of course. When the sensory powers infer things about the common sensibles, for example, they can be mistaken. But these types of mistake arise because, in these cases, the proper objects of the sentient powers are not what are under consideration. When we consider the intellect, restricting attention to its proper object, that is, to the quiddity of things, then the same considerations apply. The intellect can make mistakes, but it makes those mistakes in composition and division. The actual process of abstraction, the proper object of the intellect, does not fail provided that the intellect is not impeded.

Consequently and again, provided it is not impeded, the intellect cannot be mistaken about first principles and about immediate consequences of those first principles. These provide examples of things that are known immediately to the intellect in their quiddity and therefore are sure.

A7: If the intellect is infallible in understanding its proper object, grasping the quiddity of things, does that not mean that the intellectual abilities of all humans have to be identical? After all, either one grasps the quiddity of something or one does not; this is something that does not admit of a greater and lesser. This seems to be in conflict with the common observation that intellectual gifts differ from person to person!

Aquinas observes that, from one point of view, the argument is sound. We do either grasp the quiddity of something or we do not. On the other hand, form is received in matter according to the disposition of the matter; therefore a more powerful soul is received in a more suitable body. In addition, the sentient powers of the soul depend upon matter for their functioning; as they support the intellectual powers in the latter’s operations, they may do so for better or worse depending upon their fitness for purpose. Following the argument of the sed contra, these arguments indicate that some can think more deeply than others about the objects of intellection.

A8: Some things appear to be indivisible, in the sense that although we may be able to conceptually divide them into parts, they themselves do not exist except as a whole. Aquinas identifies a continuum as such an indivisible thing; we may be able to conceptually break it apart into points but those points only exist in potentiality in the continuum, as it were. Similarly the human reason: we may understand it in its different powers, but it is a unity in itself. In the cognition of such indivisibles, Aquinas argues that we grasp their quiddity as indivisible prior to being able to think about how they may be divided into parts. On the other hand, there are some types of indivisible that we can only define in terms of privation. A point, for example, is defined as that which has no parts. For indivisibles like these, we have to grasp their quiddity through grasping the quiddity of the privations involved. Therefore we have cognition this type of indivisible posterior to having cognition of the divisible.

Handy Concepts

  • The forms of material things that exist in the soul are the forms of those things and not only a representation of them. Therefore we have a correct understanding of reality by abstraction from phantasms because this process of abstraction involves an absolute consideration of those forms as they exist in reality.
  • When the intellect abstracts form from matter, it abstracts from this particular matter but not from matter in general. The abstraction retains the fact that the form informs matter.
  • Sensitive species are that by which some external object is sensed, intelligible species are that by which some external object is understood.
  • The expressed species of the intellect form the raw material with which we carry out the process of thinking. Our process of thinking is a complicated process of composition and division of different intelligible species in the passive intellect. We put ideas together and pull them apart repeatedly until we get something true that corresponds to reality.
  • In sensory perception we grasp the singular before the universal, but in intellectual cognition we grasp the more universal before the more particular. However, when we consider the universal in regards to its intentionality, the situation becomes more complicated. We arrive at the scope of the less universal before we arrive at the scope of the more universal; each by means of repeated acts of cognition.
  • As concerning the direct object of cognition, we can only have one object of cognition at a time. When we consider a complex object, or an object in relation to some other object, we consider them under a single form of the complex.
  • The intellect is infallible in the cognition of its proper object in a way parallel to the fact that the sensory powers are infallible in the perception of their proper objects. The proper object of the intellect is the quiddity of the object of perception. When we make mistakes in our intellectual understanding of things, it happens further along in the process of intellection. It happens when we make mistakes in the composition and division of the concepts expressed by the passive intellect.
  • Although the intellect is infallible with respect to its proper object, this does not mean that everybody has the same level of intellectual ability. The sensory powers depend upon material organs and therefore may be more or less able in the complex process of cognition. Different people may have different abilities with respect to the composition and division of expressed intelligible species.


  • Aquinas never really gives us a systematic account of where error might happen in perception and cognition. He identifies infallibility in the senses sensing their proper objects and in the intellect perceiving the quiddity of things, but he doesn’t tell us explicitly where and how things can go wrong. Error would seem to crop up in the way in which sensible species and intelligible species are composed and divided within the sentient and the intellective soul respectively. The interior senses can make mistakes concerning how the basic sense data is interpreted at the level of sensation; the intellect can reason falsely about the relationships between different intelligible species, coming to incorrect conclusions.
  • The fourth objection to the third article argues that we arrive at our knowledge of causes and principles through our knowledge of effects and that therefore the more particular must be prior to the more universal in our intellects. In the final paragraph of his answer, Aquinas states that this is not necessarily the case: sometimes we understand unknown effects through their causes. However, the rest of the answer seems to be rather odd; bypassing the actual objection and focussing on the various ways in which universals can be principles of things.
  • In the fourth article Aquinas denies that we can have simultaneous intellectual understanding of a multiplicity of things. Although his argument is reasonable, it’s a bit frustrating that he doesn’t say more about the mechanisms by which we do hold multiple things in mind. When performing a comparison of two things, we consider first one and then the other and then hold them both under the form of the comparison itself; but what goes on in detail in this consideration? Perhaps it would have been helpful for him to argue that when we consider a composite object (and after all, most things we consider is composite in one way or another) we can only consider them intellectually under one aspect at a time.
  • Aquinas flirts with the boundary between the intellectual and the linguistic (for example in the fifth article) in ways that make one wish that he had gone further. The result of the intellectual process of abstraction from phantasm is an impressed intelligible species in the passive intellect. The corresponding expressed species is the concept or word; these expressed species are then the raw material of processes of composition and division but also of the linguistic expression in words of what is inside our heads. If one were to follow through the chain of events in the process of sensation, cognition and expression one should arrive at a complete theory of how our linguistic expressions correspond to the world.
  • In the third objection to the fifth article an argument is put forward that can be developed into a powerful criticism of Aquinas’s systematic exposition of mind. In the real world things simply are the way they are: the ball simply is white. There are no processes of composition and division in the world of things that corresponds to the intellect’s processes of composition and division. The more general criticism is that we want things in the mind to be the same way (an accurate representation, perhaps) of the way that they are in the world. But to get into the mind, there has been a process of sensation, in which individual senses take apart the object of perception, only for it to be put back together by the internal senses in the phantasms. The phantasms then undergo a process of abstraction whereby various quiddities of the external object arrive in the passive intellect. A final, but on-going, process of composition and division then sticks all these quiddities back together again in true concepts about the external object. Don’t all these processes of taking-apart and then gluing-together come between us and the world? Perhaps the key to answer this objection is Aquinas’s claim for the infallibility of the senses in sensing their proper objects and of the intellect in abstracting the quiddity of things. The senses and the intellect are able to provide a faithful representation of what is out there in the external world; we are capable of error in our assessment of these data but we do have the capability to arrive at some true scientific knowledge of the world.
  • Aquinas does not tell us what could impede the intellect in the intellection of its proper object. In the case of the sentient powers, physical damage or illness could account for impediment as these involve a material organ. What might impede the immaterial intellect?