Sunday, 15 September 2013

Question 83 – Free Choice

Why this Question Matters

Whether humans have free choice of the will and if they do, how this works, have been profound questions throughout the history of human thought. Aquinas finishes off his introduction to the will with a brief consideration of these questions.

In contrast to many modern approaches to these questions, Aquinas’s is relatively low key and straightforward. He has done much of the heavy lifting for this question in setting up the framework in which the soul is an immaterial subsistent form which is the form of the body. In addition, questions of determinism are removed from consideration by the metaphysical system in which God acts as first cause for all secondary causes, be they deterministic or voluntary.

Aquinas’s strategy in this question, therefore, is to start from the seemingly self-evident; in certain circumstances, we have freedom to make a choice amongst alternatives. He then works his way towards the goal of showing that this freedom of choice arises from an appetitive power of the soul and, in fact, arises specifically from freedom of the will.

The Thread of the Argument

A1: Do we actually have freedom to make choices between alternatives? After all, if we had such a freedom, then it would appear that that we would have to be unmoved movers; nothing, after all, is moving us to the particular choice. From another point of view, we can all make the simple observation that people seem to make choices that are in accord with their personalities; so perhaps our choices are actually determined by who we are as individuals.

Aquinas’s answer is robust: of course we have freedom to choose. If we didn’t, then much of the way we think about ourselves would be rendered meaningless and many of our actions would be unintelligible if not entirely pointless. In elaborating this answer, he points to the choices that non-human animals make as being based on judgements, but on judgements that are not free; such animals do not intellectually weigh up alternatives but depend upon their sentient powers in combination with their instincts. Humans, on the other hand, make their choices among alternatives on the basis of intellectual judgements; a particular end may be inevitable for the will in some circumstances, but the means of achieving that end may be manifold and subject to intellectual judgement.

Humans do move themselves to action though the exercise of free choice; but such freedom does not imply that what is exercising that choice is a first cause of that movement. God is the first cause behind all secondary causes, be they natural or voluntary; indeed it is God’s causality that makes free voluntary causes to be free. Within each thing He operates in accord with what is proper to that thing.

In answering the objection that we make choices according to who we are, Aquinas distinguishes between how we are by birth and how we are because of subsequent developments in our personalities. He further subdivides how we are by birth into intellectual and bodily components. As far as our intellects are concerned, we do have a natural desire for our ultimate fulfilment but this is not subject to free choice (Ia.d82.a1-2); as far as our bodies are concerned, we do have natural inclinations, but these are always subject to reason. Such inclinations do not overcome the freedom of choice arising from our intellectual natures. The development of our personalities subsequent to birth, and the inclinations towards particular choices consequent upon this, is also subject to reason. We can choose to develop particular qualities or to reject them.

A2: Having established that we have freedom of choice in certain circumstances, Aquinas now wishes to establish how that choice arises. The actual choice of something would appear simply to be an act; but does that act arise from a power of the soul or from a habit, that is, from a sort of stable disposition to act in particular sorts of way in certain circumstances?

The first thing that we have to recognize is that, strictly speaking, a choice is an act. However, what we’re really concerned with in this question is not the individual act itself but the principle within the soul that allows us to place that act. How come we are actually able to make these free choice acts? Aquinas identifies that such a principle can either be a power or a habit or a mixture of the two; his strategy is to eliminate the possibility of habit being involved in the ability to make a free choice.

If the ability to make a free choice were rooted in habit, then the habit involved would either be a natural habit (i.e. a habit we are all born with) or one that we have developed. But if we look at the sorts of habits that we are born with, we soon see that they are not things that are subject to free choice; the assent to the first principles of reason, for example. On the other hand, if we look at the habits that we develop as we grow they are associated with doing things well or doing things badly (the virtues and the vices respectively, for example). Free choice in itself is indifferent to the goodness or the badness of the choice, so it is does not arise from such a habit.

It’s important to note that Aquinas is not arguing that habit is uninvolved with our actual choices; for it clearly is. He is interested in the source and principle of the ability to make free choices; his argument in this article is that natural and developed habits, although involved in the process of making particular choices, are simply not of the same type of thing that would enable us to make a choice in the first place. Having eliminated habit as a source of the ability to make free choices, the alternative that is left is that free choice is a power of the soul.

A3: The next question that Aquinas has to address is that of the location of the power of free choice. It doesn’t take much reflection to realize that most of the thinking that goes to inform our free choices takes place using the cognitive powers; so why don’t we simply attribute the power of free choice to the intellect?

In his reply to the second objection Aquinas quotes Aristotle’s Nichomachean Ethics: “When we have judged on the basis of deliberating, we desire in accord with the deliberation”. This view forms the basis for Aquinas’s position. The cognitive powers are certainly involved intimately in the process of making a choice, but the evaluation of the possibilities and the actual making of the choice itself are different acts that are associated with different powers. Again following Aristotle, he argues that the proper object of the act of choosing is a means to an end and as such should be considered to be a good and therefore an object of the appetitive powers. We come to a cognitive evaluation of the choices before us, but in order to choose one of them we have to desire that choice. Therefore the actual act of choice, as opposed to the evaluation of the possibilities, is down to the appetitive powers and therefore the will.

A4: Is the power of free choice something distinct from the will considered simply as intellectual appetite? Do we have to think of the will as having two aspects in the same way that we discovered the intellect to be made up of the passive intellect and the agent intellect? After all, the intellectual appetite is ordered towards the desiring of apparent goods put to it by the intellect; as such it sounds as if it is a passive power. Do we need to posit a corresponding active power that makes the decisions between apparent goods?

Aquinas argues that the appropriate analogy is not with the contrast between the passive and the agent intellects but with that between the intellect and reason within intellective understanding. Within the intellect there is a simple apprehension of things that may be taken as first principles that are then elaborated by a process of reasoning to previously unknown conclusions. In a similar fashion, a simple act of willing is an act of desire for something considered as an end. Choosing, on the other hand, is concerned with the means with which one can achieve that end. So, as far as the appetite is concerned, the end is related to the means to the end in a similar way in which the principle is related to the conclusion in cognitive matters. Therefore the will is related to the power to choose in a way similar to the relation between the intellect and reason. We have already seen (Ia.q79.a8) that intellective understanding and discursive reasoning belong to a single power. We should also, by means of this analogy, see that free choice and the will are also a single power.

Handy Concepts

  • There are plenty of bad books about the freedom of the will around at the moment; many of them argue from a biological determinism that is completely unaware of the strong metaphysical assumptions that their arguments make. A good introduction to the modern free will debate, however, is Robert Kane’s A Contemporary Introduction to Free Will.
  • Human beings, as intellectual animals, are able to make free choices. Freedom of choice is an appetitive power which corresponds to the ability of the will to make choices between apparent goods offered to it by the intellect as means to an end.


  • In the first article, Aquinas does not raise material determinism as an argument against the existence of free choice. In many modern formulations this is a key argument that would have to be met; but Aquinas has already shown that the human intellect is immaterial (even though it makes use of material bodies), so he simply does not have to meet this objection.
  • In meeting the objection in the first article that our choices are determined by the personality traits we have developed subsequent to birth, Aquinas argues that we have choice in whether to develop such traits or not. He begins to open up discussion on how our choices now may affect our choices much later on in life; in particular, a choice now may remove freedom of the will from some choice later on. Aquinas insists that we have responsibility for these choice-closing choices and therefore that our later un-free choices are still our responsibility because of this. The degree of responsibility will, of course, be in accord with the degree of freedom available to that earlier choice. Much more will be said about this topic in the second part of the summa.
  • At first sight, given the profundity of the question of free-will, Aquinas’s answers in this question may seem disappointingly slick. As we have remarked above, he simply doesn’t have to face the problem of material determinism, which removes much of the difficulty. However, hiding in what he has said is a significant difficulty. In order to remove the possibility that the human soul is a first mover, Aquinas argues that God is the first mover, moving the soul in accord with what is proper to something having the power of free choice. The big question is: how does that work? How does a first cause move secondary causes in accord with the latters’ natures? This question was to raise much controversy in later years!

Sunday, 8 September 2013

Question 82 – The Will

Why this Question Matters

The will is the second component of the intellectual soul; the appetite corresponding to the intellect itself. In these post-Nietzschean days in which the idea of the will to power is almost taken for granted as a self-evident truth, it is good to look back to before the disastrous late medieval ditch of nominalism and voluntarism into which philosophy fell.
The account that Aquinas describes will soon be seen to be quite alien to our modern sensibilities: the emotions are part of the sentient appetite; the will is under the command of the intellect. Aquinas is continuing to build up his account of what precisely is human in the human act. Considerations of the will itself (in this question) and of the freedom of the will (in the next question) are central to that account.

The Thread of the Argument

A1: We have only just been introduced to the will as the intellectual appetite, so we only know a little bit about how it works so far. The will is the appetite corresponding to the intellect and therefore it has an inclination towards what the intellect proposes to it as a good to be desired. Even with such little material available, Aquinas wants us to ask whether there is anything that the will must necessarily desire.

In order to answer this question we must be clear about what we mean by necessity. There are a number of possible meanings to the word that could apply to our question and which therefore could affect its answer. At the heart of it, necessities are things that are not able not to be; but the questions we must address concern the ways in which they are not able not to be.

There are certain forms of necessity that follow on from the very nature of the situation at hand. For example, it is necessary that the angles of a Euclidean triangle add up to two right angles; similarly a composition that involves contraries, such as a living organism, must by the fact of those contraries decay. These two are examples of natural necessities (the former is a formal necessity and the latter a material necessity).

On the other hand some necessities arise because of externalities. For example, if someone accepts a given goal or ambition, then they may find themselves forced to accept certain consequences in order to achieve that goal. This sort of necessity is called a necessity of the end. Similarly, some external agent may coerce someone into doing something that they may or may not otherwise wish to do. In this case, this is called a necessity of coercion.

Having gone through these, which of them might apply to the will? The first type of necessity to rule out is that of coercion. We can be forced to do something, but in being forced to do it we say that we are being forced against our will. Something cannot be both coerced and voluntary.

On the other hand, necessity of the end can apply to the will; if we have made a decision to try to achieve something and that achievement necessitates that certain means are required, then the inclination of the will towards those means is necessitated. (This does not prescind from the possibility that, under this necessitation, the will moves the intellect to “think again” about the overall object). Similarly, a natural necessity may apply to the will. For example, the will is by its very nature inclined towards the good as presented to it by the intellect; the absolute good, divine beatitude, will therefore incline the will by an absolute natural necessity.

A2: We’ve seen in the previous article that there are some things that the will wills by necessity; such as beatitude, or a necessity of means given the desired end. A slightly more subtle question is whether, given that the will is willing something, it is willing it necessarily? After all, given that the intellect is presenting an object to the will as an apparent good and that the will by its nature inclines towards what the intellect presents to it as good, does that not mean that it has no choice in the matter?

To answer this question, Aquinas makes an analogy with the intellect. There are certain things towards which the intellect has to give assent: it assents naturally to the first principles of reason. Then there are propositions which are true but which take some logical working out in order to demonstrate that they are true. Once the intellect has recognized that the demonstration works, it adheres to these propositions by necessity; but before it has understood the demonstration, necessity is not involved in its assent. Finally, there are propositions that are by their nature contingent; in this case the intellect does not assent to them by necessity.

The analogy of the intellect’s first principles of reason is the will’s ultimate end of beatitude; the good absolutely speaking. One immediately sees, however, that there are many particular goods that do not have a necessary connection with beatitude: whether I get out of bed now or in five minutes time, for example. Both of these could be particular goods seen from different aspects. It is a mistake to see the good as something simple; rather it is often made up of a complex mixture and the intellect will, in many circumstances, not present a single simple end as a good to the will, but rather will present a complex of intertwined apparent goods that may or may not be consistent with one another. The will chooses which ones it inclines towards (and this, of course, leads on to questions of the freedom of the will, discussed in the next question of this treatise).

There are particular goods that have a necessary connection to beatitude and once that connection is seen the will is necessitated towards them. However, in this life we see “as through a glass darkly” and that necessary connection may be obscured to us. For the blessed in heaven, granted an immediate vision of the divine essence, they necessarily will that beatitude and all that goes with it.

A3: By now it will come as no surprise that Aquinas is interested in which is the higher power, the intellect or the will. This question is not about which is in command of which; the relationship between the intellect and the will and how they work together in the human act will come later. Here the question is about the hierarchy of being.

Aquinas looks at this question in two ways. First of all he considers it in absolute terms and then he considers it from a relative point of view in varying circumstances. Looking at the question absolutely he concludes that the intellect is superior to the will because the object of the will, which is the desirable good, is include amongst the objects of the intellect. In this sense, the object of the intellect, that is the true, is simpler and more absolute than the object of the will.

On the other hand when we consider the intellect and the will in action, there can be some cases in which the object of the will exists in a higher entity than the object of the intellect. What Aquinas is driving at is that the object of the intellect lies within the intellect itself and the object of the will is precisely the good thing that is willed, external to the soul. So, when someone considers God intellectually, leading their will to incline themselves towards God through love, then we can say that the love of God is greater than the cognition of God because the cognition of God is within the intellect whereas God as object of the will is God Himself! On the other hand, in considering an ordinary everyday corporeal object, the cognition of it is better than the love for it. The intellect-in-knowing-the-object is greater than the object itself.

A4: We know that the intellect presents the will with an object to be desired as its end and in this way can be thought of as moving the will. Is the converse true? That is, does the will move the intellect? It does, but in a different way to the final causality with which the intellect moves the will. The will moves the intellect, and the sentient powers of the soul, as an agent. The idea here is presented through an analogy with kingship; in order to achieve some final goal the king orders his subordinate officers to apply their skills to ends appropriate to their abilities that contribute to the final goal. Likewise the will, which is ordered to the good, moves the intellect and the sentient powers of the soul as appropriate to the achievement of that good. We see here the beginnings of an account of the human act that will be elaborated later on in the summa. My intellect presents the will with the end of getting into town to do some shopping. The will moves the intellect to work out the best way of getting there and the sense of sight to read the bus timetable and so on. As we saw in the previous article, absolutely speaking the intellect is the superior power to the will. However, when we consider them in a particular human act, the intellect understands that the will wills and the will wills that the intellect understands; the good (the object of the will) is contained under the true (the object of the intellect) insofar as the good is a certain true thing that is understood and the true is contained under the good insofar as the true is a certain desired good.

A5: The sentient powers are divided into the irascible and the concupiscible; is the will divided in the same way? To answer this we must return to Aquinas’s criterion for the division of powers: powers that are ordered towards some common notion cannot be divided. The sentient powers are naturally divided by the different types of object proper to each of them, but the will is ordered towards the good, under the common notion of good. There may be many different types of good but they are all under this common notion. Hence there is no division of the will into the irascible and the concupiscible.

The first objection points out that the words irascible and concupiscible come from words to do with anger and desire respectively and it would seem that some instances of anger and desire stem from the intellective appetite and not from the sentient powers. This is an example of where we have to carefully tease apart the roles of intellect and sentience that are so intertwined in humans. The simple desire for or aversion to something is down to the will, but the concupiscence or irascibility that go along with these movements of the will are due to the sentient powers.

Handy Concepts

  • The will is the intellectual appetite; it inclines towards those things presented to it as apparent goods by the intellect. The will can be necessitated with a necessity of means and sometimes by a necessity of the end, but the will cannot be coerced.
  • The human act is complex; the intellect presents the will with a complex of apparent goods and the will, choosing among them, can move the intellect and the sentient powers in the elucidation or the execution of the act chosen.
  • Despite the feedback loop implied by this understanding of the intellect and will, absolutely speaking the intellect is the superior power.
  • The will is not divided into irascible and concupiscible powers; these latter are restricted to the sentient powers and the corresponding passions (or emotions) reside within these.


  • Aquinas argues that the will cannot be coerced. We would agree that we may be forced to do things against our wills, meaning that we shall do them but we do not will them. But what about the situation where the will is broken, under torture, for example or where the will is turned, as in the so-called Stockholm syndrome? Has the will been coerced in these situations to will what it would otherwise not will? In these situations we must remember that the will inclines towards what the intellect presents to it as an apparent good; if the intellect gets it wrong (in an absolute sense) it’s the fault of the intellect not of the will. These situations of apparent coercion of the will are really coercion of the intellect: by fair means or foul the intellect is persuaded to see objective evils as apparent goods and to present them to the will as goods.

Question 81 – The Sentient Appetite

Why this Question Matters

Aquinas has discussed the appetites from a generic point of view in the previous question; now it is time to divide these appetites into those of the sentient powers (in this question) and of the intellectual powers (in the next question). In this question we’ll see that the sentient appetite is divided into two classes, one of which is to do with desire or aversion, and the other of which concerns the impulse to overcome obstacles in the fulfilment of these basic desires. In addition, we’ll begin to see that the sentient appetite is the context within which the passions (or emotions) fit; and Aquinas will make a start on his plan of how the powers of the soul work together.

The Thread of the Argument

A1: In asking whether sensuality is a purely appetitive power, Aquinas is trying partly to answer a question concerning the use of language. We’ve already seen that the sentient appetite is the appetite corresponding to sentient apprehension; the senses apprehend something and appetite inclines the animal towards or away from that something. But the word sensuality needs to be connected with this notion of being an appetitive power. This argument is completed by the etymological observation that sensuality appears to come from the Latin for a sensual movement.

A2: Aquinas, following an ancient tradition of Christian anthropology divides the faculty of sentient appetite into two powers, the irascible and the concupiscible. The basis for this division is that there is not simply an appetite towards or away from some object of perception, but also an inclination towards overcoming obstacles in the pursuit of or flight from that object. The first of these, the inclination towards those things that are agreeable or away from those that are harmful, is called the concupiscible appetite. The second, the inclination to overcome obstacles, is called the irascible appetite.

The obvious question arises as to whether one should really consider the irascible and the concupiscible appetites as two separate powers or as different aspects of the same power. The argument in favour of recognizing them as separate is twofold. In the first place, they perform separate functions in recognizing the objects of desire (or fear) and the obstacles to the possession of (or flight from) these objects; in the second case, they seem to oppose one another in some circumstances. The arousal of passions such as anger in support of the irascible appetite can lessen the desire of the concupiscible, and vice-versa.

A3: We’re gradually working our way through the components that go to make up human psychology. Of course, an interesting question that Aquinas will address at length in due time, is that of how the different powers of the soul interact to make up the acts that are particular to humans. In this article he begins such an enquiry by asking whether the irascible and concupiscible appetites are under the control of reason. It’s easy to think of arguments against such as position; after all, our experience of the passions would suggest that they have an alarming tendency to go out of all control!

Aquinas argues that the sentient appetites are under the control of reason in two ways. They’re under the control of the intellect with respect to what they do and under the control of the will with respect to how they go about doing things.

In arguing for the first of these positions, Aquinas identifies one of the ways in which the human animal is different from non-intellectual animals. In non-human animals the sentient appetite is often moved by the estimative power, the power that determines the desirability or threat offered by a perceived object. This interaction is at a level below that of the intellect or reason. When we turn to the human animal, however, we recall that the estimative power is replaced by the cogitative power; this power interacts with reason in its estimation of an object. Therefore Humans can bring to bear the powers of discursive reasoning before the sentient appetites are deployed. The second position, that the sentient appetites are under the control of the will, follows because the appetites are ordered in a hierarchy; the will being the highest of these appetites.

In his reply to the second objection, which sees the sentient appetites fighting against the will, Aquinas brings out one of his most quoted analogies. He claims that the soul rules the body like a despotic ruler, whereas the will rules the appetites as a constitutional or royal ruler. The point is that parts of the body have no alternative but to do what the soul tells them to do: a foot or hand moves when it is told to or reacts automatically in accord with the habits of the soul. The will on the other hand has to interact with sentient appetites that can, through their own powers, resist or cajole the will. There is some give and take in the control the will has over the sentient appetites but, as we see in any constitutional polity, this does not imply that the sentient powers do not obey the will.

Handy Concepts

  • The reference to Gregory of Nyssa in the sed contra of the second article is in fact to a treatise called de natura hominis, written around 400AD by Nemesius of Emesa.
  • In the context of the irascible appetite we see Aquinas make mention of the passions. He will have much more to say about these, especially in the so-called Treatise on the Passions in I-II.qq22-48. Briefly, there are six passions of the concupiscible appetite (joy, sadness, desire, aversion, love and hatred) and five passions in the irascible appetite (hope, despair, courage, fear and anger).
  • The third article of this question raises aspects of the question of the interaction between the intellect and the sentient appetite. There is much more to say about how the powers of the soul interact and Aquinas will focus on this issue in the Treatise on The Human Act in I-II.qq6-21.


  • Despite Aquinas’s arguments in the first article, in English the word sensuality seems utterly lost to theology! Now it is most associated with features of the object of perception rather than moved subject. In Latin, it first appears in Tertullian (as does so much Latin theological terminology) where it means the capacity for sensation; so it appears to have done the rounds in order to end up standing for the sensitive appetite.
  • In the third article, arguing for the idea that the sentient appetites are under the control of the will, Aquinas states that “The lower appetite is not sufficient to effect movement unless the higher appetite consents”. Although he doesn’t state it, Aquinas’s analogy with constitutional rule in the reply to the second objection suggests that the consent of the higher power may often be implicit. The will doesn’t have to explicitly approve every action of the sentient appetites; rather one can see subsidiarity in the relationship.

Tuesday, 3 September 2013

Question 80 – The Appetitive Powers in General

Why this Question Matters

Aquinas spends quite a lot of time and effort in this treatise on the discussion of cognition and the intellect. We’ve just had the very lengthy Ia.q79 and we’ll return to the intellect in a series of questions Ia.q84-9. It’s time now, though, for a brief interlude on the appetitive powers, and in particular on the intellectual appetite, better known as the will. This short discussion may seem somewhat inadequate, but it’s important to remember that Aquinas will spend much effort in discussing individual aspects of the appetitive powers in the second part of the summa. Indeed, one could argue that the second part as a whole is a working out of the consequences of the relationship between the sentient and intellectual appetites in man.

In this question Aquinas devotes two articles to the appetitive powers considered in general. In the first he discusses whether appetite should be considered as a power of the soul separate from those that we’ve already considered; having answered this question in the positive he discusses whether the appetitive powers corresponding to the sentient and intellectual powers are distinct. Although he doesn’t make a lot of it in this question, one of the underlying themes in Aquinas’s treatment of the appetitive powers is that the existence of intellect and will in humans in addition to the sentient powers gives rise to a qualitative difference between the human appetite and the animal appetite even if the desired object is of the same class.

The Thread of the Argument

A1: Appetite and appetition describe an inclination towards or a seeking for something. We’ve already seen (Ia.q59.a1) Aquinas discuss the difference between the natural appetite, the sensible appetite and the intellectual appetite (or will) in the context of the discussion about angels; now he turns to the appetites in the context of the human soul.

Aquinas argues that appetite is a specific power of the soul. To do this he recalls that any form is associated with some sort of inclination; forms have innate tendencies towards things when instantiated in matter. The forms of things that lack knowledge have natural inclinations that are called natural appetites. In things that possess knowledge, on the other hand, the knowledge that they have inclines the knowing being towards (or away from) the objects of which they have knowledge. This inclination that surpasses the natural appetite is an appetitive power that belongs to the soul.

A2: Given that beings possessing knowledge have appetites that exceed the natural appetite, one must ask whether different types of knowledge, such as the sentient and the intellectual give rise to distinct powers in the soul. Appetites are passive powers that are moved to actuality by the forms of the things that are the objects of knowledge, and are distinguished by the nature of their relations to that knowledge. Since what the intellect apprehends is generically different from what the sentient powers apprehend, the corresponding sentient and intellectual appetites are distinct.

One might argue, as does the second objection, that the distinction between the objects of knowledge of the sentient and intellectual powers is not sufficient to distinguish the corresponding appetites, because the appetite is for something singular. We recall that intellectual knowledge is of the universal and so, in order to be inclined to the individual, knowledge retained from the sentient powers must be involved. In other words, in order to have an inclination towards a concrete individual, the intellect must revisit the sentient and the boundary between the two becomes blurred. Aquinas’s answer is that the intellectual appetite inclines to something external as a universal; it desires it because it is good, not because it is that individual. The implication of this is that the appetites of an intellectual creature such as man operate in a different order than those of other animals; the animal appetite for an external object is based purely on sense experience, but the human appetite combines the sentient and the intellectual. Even when the desired object is of the same class, a tasty morsel for example, the human desire for it is of a different order that the animal desire for it. We will see more about this is the next question (Ia.q81.a3) where the question of the relationship between the sentient and the intellectual appetites is discussed.

Handy Concepts

  • Appetite is distinct power of the soul.
  • The sentient appetite and the intellectual appetite, or will, are themselves distinct powers.

Question 79 – The Intellective Powers

Why this Question Matters

After having considered the powers of the soul in general and the specific sentient powers of the soul in particular, Aquinas now turns his attention to the intellect. Although this is a very lengthy question, with thirteen articles, he will have only just begun consideration of the intellect by its end. Questions Ia.q84-9 will be devoted to the specific ways in which the intellect functions in detail; this question deals with an overview of the intellective powers of the soul.

The intellect is what differentiates humans from other animals. The fact that our intellects give us understanding of universals, extracted from the perception of concrete particulars, affects both the ways in which our sentient powers function with respect to their particular objects as well as the ways in which our appetites reach out to those objects. If we return to Boethius’s definition of a person as “an individual substance of a rational nature”, we see that to a very great extent, intellect is what defines us.

The Thread of the Argument

A1: In the summa theologiae we often see the pattern whereby the opening article of a question answers the most important issues to do with that question and the remaining articles work out the details, frame the corollaries or simply mop up loose ends. In this extraordinarily long question about the intellect, however, this pattern is broken. The opening article asks whether the intellect is a power of the soul or whether it is the soul’s essence; a question that has already been answered in Ia.q77.a1! Indeed, the answer given is simply a reiteration of the answer given previously; it is only in God that intellect and essence coincide, as the only time the immediate principle of an operation is the essence of a thing is when the operation is the thing’s esse.

One looks to the objections to see if Aquinas has taken the opportunity to knock down some powerful new counter argument; but the objections are all simple misunderstandings or equivocations. It appears that Aquinas just wanted to reiterate the fundamental nature of the intellect as an introduction to the meaty issues to come.

A2: The function of the intellect is to abstract the universal features, the quiddity, of the object of perception from the intentional species provided by the sensitive powers of the soul and to receive and retain them. We will see that this means that there is both an active and a passive component of the intellect. In this article, Aquinas considers the passive (or potential) part of the intellect; in the next he will turn to the active or agent intellect.

In considering whether we can think of the intellect as a passive power, Aquinas looks at the meaning of the word passive; he promptly eliminates a couple of candidate meanings from those which might apply to the intellect. For his purposes he interested in taking passive to mean anything that passes from potentiality to actuality. The reason for this is as follows. The intellect of God is purely actual in creatively knowing all things real or virtual. No created intellect, however, can be in actuality to the entirety of knowledge; otherwise it would not be a finite being. The knowledge that the angels have is in actuality because of the way that they know things, but they know only what has been infused within them. In contrast, the created intellect of the human being has to pass from potentiality to actuality in learning something new. Quoting Aristotle, Aquinas points out that our intellects start “like a clean tablet on which nothing is written”.

A3: If the intellect was purely passive, then we would have a problem. The end result of the process of sensation is an intentional form in the soul that is the form of a concrete individual thing. As such it is still individuated by the matter that it informs it in the actual individual thing. In order for something intelligible to be received in the passive intellect another stage has to be gone through; the quiddity of the individual object has to be abstracted in order to arrive at the intelligible species that will be impressed upon and retained in the passive intellect. The power that performs this function is called the agent intellect.

Aquinas points out that under Plato’s understanding of forms, there would be no need for such an active power. In Plato’s system forms of things exist independently of the things themselves; that is, apart from matter, and are therefore directly intelligible to the (passive) intellect. For Aristotle, the forms of concrete things cannot exist independently of the things themselves; there needs to be an active power abstracting the intelligible content from the concrete object.

The first objection attempts to make a parallel between intellection and sensation; there is no need for an active power to extract the sensible species from a concrete object, why therefore need one be posited for intellection? The difference is that the concrete object itself provides the actuality that moves the sensitive powers to actuality, so there is no need for an active sensitive power. But the intellect has to work on what is produced by the sensitive powers and this has not been entirely removed from materiality; the sense organs at the very least are still involved. Actuality and potentiality work in the same genus; in order for a potentiality to be moved to an actuality by some being in actuality, that being has to be in the same genus as the potentiality. Therefore the materially involved sensitive species cannot move the immaterial potentiality of the intellect to actuality; there needs to be an immaterial agent in actuality in order for that to happen.

A4: In the third article we have seen that there must be an active power moving the passive intellect; but does this power have to be part of the soul? To our eyes, this may seem a very strange question to ask but in the middle age it was a live question. The function of the active intellect is so extraordinary, abstracting the quiddity of objects from the phantasms provided by the senses, and so particular to the human condition, that one might easily attribute it to the divine. As psalm 4 says: “The light of your countenance, Oh Lord, is signed upon us”. Indeed, Aquinas inherits from Augustine the tradition of explaining intellectual understanding in terms of divine illumination: it is God himself who acts directly on our intellects so that we get to the heart of what things really are.

Aquinas sees things differently than this tradition. He argues, gently in this article but more forcefully elsewhere, that the act of understanding belongs genuinely to us. Here he says “We know this (that the active intellect illuminates phantasms) when we perceive ourselves abstracting universal forms from particular conditions”. His point is a vital one; one that must be made in face of any argument that would underestimate the importance of the fact of the experiencing subject. It is I that understands what I am currently understanding and I am experiencing the fact that I am understanding. Any theory of mind that does not explain the subjective nature of the experiencing subject is worthless.

Applying this principle to the question in hand we see that the active part of my intellect must belong to me and, in particular, to my soul. That is not the end of it, though. The active intellect begins to look very much like a first mover; something that sits at the start of a chain of per se causation. However, this is where divine illumination correctly sits; God is the only first mover in the universe and it is He that moves our active intellects to the act of illuminating the phantasms.

A5: One of the medieval theories that had much purchase at the time St. Thomas was writing was the idea that the agent intellect was a unity, shared between all human beings. The fact that this was such an important theory explains why he this out to have its own article; he has, of course, already answered the question. The agent intellect is a power of the soul of each individual person; each person’s illumination of the phantasms is personal. Therefore the agent intellect is not shared between human beings, as one and the same power cannot be shared between substances.

One of the curious facts about human beings working to support the idea of the single agent intellect is that we all share in the most fundamental conceptions of the intellect; after all, if we didn’t there could be no communication between us. However, Aquinas argues in the reply to the third objection that this is simply down to the fact that humans are all in one species; everyone shares in an action that is derived from the nature of the species.

A6: We saw in Ia.q78.a4 that the sentient part of the soul possesses a power of memory; past sensory experiences can be brought to mind and the common sense acting together with the imagination can re-form phantasms (or can imagine new phantasms based on past experience) upon which the active intellect can act. Aquinas now asks whether there is a corresponding power of memory in the intellective part of the soul. More specifically, does the intellect have the ability to conserve intelligible species that are not currently being apprehended?

Aquinas spends some time discussing the point of view put forward by Avicenna in his commentary on Aristotle’s de anima. According to Avicenna, memory is purely a function of the sentient soul; if the intellect wishes to turn to a recollection of the past, the active intellect has to return to the phantasms provided by the internal sensory powers. The passive intellect retains nothing; it can only consider what the active intellect is currently presenting to it. Aquinas argues that this opinion is inconsistent with what Aristotle says in the de anima. The passive intellect receives and retains the intelligible species presented to it by the active intellect. The fact that an intelligible species is present in the passive intellect does not mean that it is always currently being comprehended; rather the passive intellect is in first potentiality for receiving intelligible forms in the first place and in second potentiality for actually considering them at any particular moment. I may have the ability to speak in French, but that does not imply that I am actually speaking in French right now.

So, there is the power of memory in the intellect insofar as the passive intellect retains the intelligible species impressed upon it by the active intellect. However, we must note that the passive intellect retains the quiddity of things and not their instantiation as concrete objects. It has an intellective understanding of man insofar as he is a man, for example. For the intellect to consider the temporal context of the intelligible species it has retained, it needs to turn to the sentient part of the soul which remembers both that it was sensing at a past time and that it was sensing a man at that past time.

In the reply to the second objection, Aquinas turns to the reflexivity of intellection. The intellect has an intellective understanding of itself as a particular intellect. What is more, it has an intellectual understanding of a particular act of its own intellectual understanding that exists at a particular time. So, although the temporal context of the object of the intellect does not belong per se to the intellect (this is supplied in conjunction with the sentient powers), the temporal context of the act of the intellect is retained in the passive intellect. In other words, when one senses an external thing, the sentient powers produce a phantasm from it (which is an intentional sensible form not entirely removed from matter) and the active intellect abstracts the sensible species from it for impression upon the passive intellect. This act of abstraction by the active intellect, together with any further acts of the passive intellect in the intellection of the object are themselves an immaterial object of the intellect that are retained by it.

A7: When we considered the sentient powers of the soul, we identified memory as a distinct power. Is it also true of intellective memory, that it is a distinct power of the soul? Given what we have already seen in the sixth article, we should not be surprised that Aquinas argues that there is no separate power of intellective memory; retention of intelligible species is part of the very definition of the passive intellect. In order to bolster this position he returns to first principles. In order to identify a diversity of powers, one must identify a diversity of objects of those powers; in addition, if the object is specified generally (as for vision), one must not take particular differences (such as black versus white) as specifying diverse powers. The object of the intellect is being in general and it is the passive intellect that becomes the things that it cognizes in receiving the forms of those things in their intentional existence. Although we can identify a distinct active power responsible for the abstraction of intelligible forms from phantasms, there is leeway for further diversification of powers.

A8: So far in this question, we’ve been talking about the intellect and intellective activity. Another word that we frequently use in talking about thinking is reason, the word that lies at the root of identifying humans uniquely as rational animals. Are intellect and reason distinct powers? Aquinas thinks not. To argue his position he recalls that the intellect is concerned with the simple apprehension of intelligible truth; that is, to understand things as they are in their natures. On the other hand, to reason is concerned with proceeding from one set of things that are understood so as to arrive at a new set of things that are understood by using certain processes such as judgement and logical reasoning. He makes analogies comparing the connection between intellect and reason with the connection between movement and coming to rest and possession and coming to acquire. These latter two pairs are each traced back to single powers; it is the same with the intellect and reason. Intellective understanding is like being at rest whereas the process of reasoning is like being in motion; reasoning terminates in new intellectual understanding just as motion terminates in rest. Therefore we should not identify the intellect and reason as separate powers.

A9: It’s not unusual to think of ourselves as sometimes pondering the higher things in life; time, eternity, God, higher mathematics, necessary beings. At other times, we have to turn our attention to lower things: whether I can pay the mortgage this month, which party I should vote for in the election. That we consider some things to be higher and some to be lower might suggest to us that we have a higher reason and a lower reason for thinking about each. Aquinas disagrees and his disagreement shows the importance to him of the unity of how we go about discovering things and thinking about them. If we consider the higher things in life as corresponding to the eternal and the lower things as corresponding to the temporal, then we have to admit that the cognition of each is related to the cognition of the other. When we discover the eternal things in life we go about it by means of the temporal (and Aquinas makes reference here to Romans 1:20). When we think about the temporal, we do it in the context of our knowledge of the eternal.

Aquinas is willing to concede that the way we arrive at the eternal through the temporal and the way we arrive at the temporal from the eternal can belong to different habits, but he insists that they belong to the same power. Now a habit (Latin habitus) as far as Aquinas is concerned is a sort of expertize arrived at through lengthy practice (and we’ll be seeing much more about habits in II-I and II-II of the summa). One has the habit of medicine if one is a good doctor; one has the habit of piano playing if one is an accomplished pianist. Within the intellectual power there are diverse ways of arriving at knowledge. Much of what we have been discussing so far in this treatise concerns the immediate knowledge of apprehension; but other types of knowledge are arrived at through arduous processes of reasoning. These different arduous processes correspond to diverse habits. Arriving at knowledge of the eternal simply involves different habits than those used to arrive at knowledge of the temporal. Similarly, if one identifies (as does the second objection) the higher with the necessary and the lower with the contingent, these still do not call for separate powers but rather for different habits of acquiring knowledge.

A10: Given what we’ve seen already, asking whether intellective understanding is a power distinct from the intellect may seem decidedly odd; intellective understanding simply is the act of the intellect. However, the point of this article is to allow Aquinas to clear up some misunderstandings of terminology that might arise when considering various other authors writing on the subject of the mind.

Aquinas starts off with an interesting linguistic aside comparing how angels are referred to in some books translated from Arabic (presumably Avicenna) compared with some translated from the Greek (presumably Dionysius the Areopagite). But the main point to be made is that although philosophers refer to intellective understanding and to the active intellect, the passive intellect, the habitual intellect and the acquired intellect, there really are only two diverse powers amongst these. The passive intellect can be considered as being in act where it is called intellective understanding or the acquired intellect; this is when it is in the act of intellection of something. It can also be considered when it is in (first) potentiality, ready to have an intelligible species impressed upon it by the active intellect, and then it is simply the passive intellect. Finally in can be considered in the state of first actuality (or second potentiality) where it has received an impressed species but is not actually thinking about it now, where it is called habitual intellect.

The reply to the third objection allows Aquinas to slice the terminology up another way. When the intellect apprehends something, this is called intellective understanding. If it orders what it has apprehended towards the apprehension of something else, this is called intention. Carrying through this process is then called excogitation (or thinking things out). Finally when it combines what it has thought out with some other certain knowledge in an act of judgement, it is said to know or to be wise.

A11: Another way in which one might wish to try and slice up the intellect is into the speculative intellect and the practical intellect. The former is ordered towards truth, the latter towards the good. Put another way, the speculative intellect is that part of the intellect that enables one to know which things are true and which are false, the practical intellect works out what is good and what is not in order that we may or may not take action towards them. In considering whether these are two different powers, Aquinas returns to the principle that one does not diversify powers simply because of an incidental difference in object. That the practical intellect is ordered towards action whereas the speculative is not counts as an incidental difference and therefore they cannot be identified as diverse powers; their objects do not really differ inasmuch as the true and the good can be considered to include one another.

A12: Synderesis is the term used to describe our apprehension of the very first principles of human action. One can find parallels to synderesis in our understanding of the very first principles of reason: the law of the non-contradiction or some form of the law of sufficient reason, for example. When we look at human action, we may think of the opening of Aristotle’s Ethics: “the good has rightly been declared to be that at which all things aim” as pointing towards one of the principles of synderesis. The term itself has a rather obscure historical background: it appear to have been used by Jerome in his commentary on Ezekiel. Unfortunately although Jerome indicates that synderesis is some sort of initial spark of conscience, he doesn’t really differentiate the term clearly from his use of the word conscience (syneidesis in Greek). This has led some to suggest that the term synderesis came about as a result of the error of a copyist of the manuscript! If the term came about as the result of a mistake, it was a happy mistake as it’s the sort of term that philosophy would have to invent if it didn’t exist.

Aquinas asks what this ability to apply the first principles of practical reason is: is it a distinct power of the soul? Aquinas observes that just as we reason on the basis of certain naturally known principles from premises to conclusions in the field of speculative enquiry, so also do we proceed in the field of practical reason. Therefore, just as there are these innate principles that allow us to reason speculatively, so there must also be innate principles that allow us to reason practically. These powers make up a habit (Latin habitus); that is, a sort of expertize in reasoning. In contrast to the types of habit that are learned through extensive practice (such as the habit of medicine and the habit of playing the piano), synderesis is an innate habit bestowed upon us by nature.

A13: In contrast to synderesis, the idea of conscience is much better known; unfortunately it is also widely misunderstood! Conscience is the ability of the practical reason to reach a judgement on the moral worth of a particular concrete action; it is often mistaken for a faculty of the speculative intellect ordered to the assessment of classes of action in general. So, the sort of judgement that the conscience is capable of making is: “was what I did yesterday an act of stealing?” rather than a judgement of the form “is stealing sometimes morally acceptable?”

Following the pattern of the last article, Aquinas asks whether conscience is a distinct power of the soul. Since conscience is knowledge applied to some individual case, it is strictly speaking an act and not a power of the soul. However, we often use the term conscience to refer to the ability to make that application of knowledge to what we do; that is, we confuse the habit of synderesis with the act of conscience.

Handy Concepts

  • The intellect is a power of the soul, which can be divided into a passive part that receives and retains the intelligible species abstracted from the phantasms produced by the sentient intellect; and an active part that is responsible for this process of abstraction.
  • We see the action of God as first mover in moving the active intellect to its act of abstraction.
  • Aquinas combats a number of contrary positions by insisting that any act of intellection is the act of an experiencing subject; any theory that fails to explain the experiencing I is short of the mark.
  • Intellectual memory involves the sentient parts of the soul in remembering the temporal context of events; the reflexive understanding of the act of understanding is directly retained in the passive intellect.
  • Reason involves putting to use those intelligible species retained in the passive intellect; it does not constitute a separate power of the intellect.
  • When we consider ways of dividing the intellect such as into higher and lower reasoning or into speculative and practical thinking, we do not thereby come across separate powers. These divisions consist in different ways or habits of reasoning within the same power of the intellect.
  • Synderesis, which gives us the first principles of practical action, is an innate habit.
  • Conscience, by which we make a judgement on the concrete act, is an act.


  • If Aquinas’s quotation of Aristotle in the second article, that the intellect is “like a clean tablet on which nothing is written”, seems to us to run counter to modern psychology, we must remember exactly what the two earlier scholars mean by “intellect”. We are well aware these days that animals are born with innate behaviours; but we must also remember that this was perfectly well known in the time of the ancient Greeks as well! Aristotle and Aquinas do not mean that we are born with empty minds and have to learn everything; they mean that we have not had the quiddity of any concrete object impressed upon our passive intellects. Although we would now have to push the boundaries of such learning to before birth, the fundamental point remains.
  • The treatment of synderesis and conscience given here may come as a bit of a disappointment. Aquinas gives much greater attention to them in questions 16 and 17 of the Disputed Questions de veritate.