Summa Theologiae

Thomas Aquinas

Question 49

On habits

[Summary of first three articles]

“Habit” as we speak about it here refers to a stable mode or determination of something in relation to its nature. And since nature is a final cause, insofar as a thing acts to fulfill its nature, such a determination involves good or evil, and thus the Philosopher defines a habit as “a disposition according to which someone is disposed well or badly” (Metaphysics V) or as “that according to which we stand well or badly in regard to passions” (Ethics II).

Since the perfection and end of anything is in its activity, every habit implies, at least indirectly, a relation to activity. In addition, since a power is essentially ordered to act, any habit that pertains to a power is directly ordered to activity.

Article 4

Whether habits are necessary¹

Response:

It should be said that as we have said above (aa. 2,3), habit implies a disposition in relation to a thing’s nature, and to its activity or end, by reason of which disposition it is well or ill disposed to it. Now for a thing to need to be disposed to something else, three conditions are necessary. The first condition is that what is disposed should be distinct from that to which it is disposed, and thus related to it as potentiality is to act. Hence, if there is a being whose nature is not composed of potentiality and act, and whose substance is its own activity, which itself is on account of itself, there is no place for habit and disposition, as is clearly the case in God.

The second condition is, that what is in a state of potentiality in regard to something else is capable of determination in several ways and to various things. Hence if something is in a state of potentiality in regard to something else, but in regard to that only, there is no place for disposition and habit; for such a subject of its own nature has the due relation to such an act. Wherefore, if a heavenly body is composed of matter and form, since that matter is not in a state of potentiality to another form, as we said in the First Part (q. 56, a. 2), there is no need for disposition or habit in respect of the form, or even in respect of activity, since the nature of the heavenly body is not in a state of potentiality to more than one fixed movement.

The third condition is that in disposing the subject to one of those things to which it is in potentiality, several things should come together, capable of being arranged in various ways, so as to dispose the subject well or badly to its form or to its activity. Wherefore the simple qualities of the elements, which belong to the natures of the elements in one single fixed way, are not called dispositions or habits, but “simple qualities,” but we call dispositions or habits, such things as health, beauty, and so forth, which imply the arrangement of several things which can be arranged in various ways. For this reason the Philosopher says (Metaphysics V, text. 24,25) that “habit is a disposition,” and disposition is “the order of that which has parts either as to place, or as to potentiality, or as to species,” as was said above (a. 1, ad 3). Wherefore, since there are many things for whose natures and activities several things must come together which may be arranged in various ways, it follows that habit is necessary.

Question 50

On the subject of habits

Article 3

Whether there can be any habits in the powers of the sensitive parts

Objections:

It seems that there cannot be any habits in the powers of the sensitive parts.

2. For the sensitive parts are common to us and the brutes. But there are not any habits in brutes, since in them there is no will, which is put in the definition of habit, as we have said above (q. 49, a. 3). Therefore there are no habits in the sensitive powers.

3. Further, the habits of the soul are sciences and virtues, and just as science is related to the apprehensive power, so is virtue related to the appetitive power. But in the sensitive powers there are no sciences, since science is of universals, which the sensitive powers cannot apprehend. Therefore, neither can there be habits of virtue in the sensitive part.

Response:

The sensitive powers can be considered in two ways: first, insofar as they act from natural instinct: secondly, insofar as they act at the command of reason. Insofar as they act from natural instinct, they are ordered to one thing, even as nature is; but insofar as they act at the command of reason, they can be ordered to various things. And thus there can be habits in them, by which they are well or ill disposed in regard to something.

Replies to objections:

2. To the second it should be said that the sensitive powers of brute animals do not act at the command of reason, but if they are left to themselves, such animals act from natural instinct, and so in brute animals there are no habits ordered to operations. There are in them, however, certain dispositions in relation to nature, as health and beauty. But because by man’s reason brutes are disposed by a sort of custom to do things in this or that way, in this way habits can be said to be in them in some way; hence Augustine says (Eighty-three Questions, q. 36): “We find the most untamed beasts deterred by fear of pain from that wherein they took the keenest pleasure; and when this has become a custom in them, we say that they are tame and gentle.” But the habit is incomplete, as regards the use of the will, for they do not have the power of using or of refraining from using the habit, which seems to belong to the notion of a habit. And therefore, properly speaking, there can be no habits in them.

3. To the third it should be said that the sensitive appetite has an inborn aptitude to be moved by the rational appetite, as stated in On the Soul III, text. 57: but the rational powers of apprehension have an inborn aptitude to receive from the sensitive powers. And therefore it is more suitable that habits should be in the powers of sensitive appetite than in the powers of sensitive apprehension, since in the powers of sensitive appetite habits do not exist except according as they act at the command of the reason. And yet even in the interior powers of sensitive apprehension, we may admit of certain habits whereby man has a facility of memory, thought or imagination: wherefore also the Philosopher says (On Memory and Remembering II) that “custom conduces much to a good memory”: the reason for this is that these powers also are moved to act at the command of the reason.

The exterior apprehensive powers, on the other hand, such as sight, hearing and the like, cannot receive habits, but are ordered to their determinate acts according to the disposition of their nature, just as the members of the body are—habits are not in them, but rather in the powers which command their movements.

Article 4

Whether there is any habit in the intellect

Objections:

It seems that there are no habits in the intellect.

3. For a habit is a disposition by which we are well or ill disposed in regard to something, as is said (Metaphysics V, text. 25). But that someone should be well or ill disposed to an act of the intellect is due to some disposition of the body; hence it is said (On the Soul II, text. 94) that “we observe men with soft flesh to be quick witted.” Therefore the habits of knowledge are not in the intellect, which is separate, but in some power which is the act of some part of the body.

Response:

It should be said that concerning intellective habits there have been various opinions. Some, supposing that there was only one “possible” intellect for all men, were bound to hold that habits of knowledge are not in the intellect itself, but in the interior sensitive powers. For it is manifest that men differ in habits; and so it was impossible to put the habits of knowledge directly in that, which, being only one, would be common to all men. Wherefore if there were but one single “possible” intellect of all men, the habits of science, in which men differ from one another, could not be in the “possible” intellect as their subject, but would be in the interior sensitive powers, which differ in various men.

Now, in the first place, this supposition is contrary to the mind of Aristotle. For it is manifest that the sensitive powers are not rational by their essence, but only by participation (Ethics I, 13). Now the Philosopher puts the intellectual virtues, which are wisdom, science and understanding, in that which is rational by its essence. Wherefore they are not in the sensitive powers, but in the intellect itself. Moreover he says expressly (On the Soul III, text. 8,18) that when the “possible” intellect “is thus identified with each thing,” that is, when it is reduced to act in respect of singulars by the intelligible species, “then it is said to be in act, as the knower is said to be in act; and this happens when the intellect can act of itself,” i.e. by considering: “and even then it is in potentiality in a sense; but not in the same way as before learning and discovering.” Therefore the “possible” intellect itself is the subject of the habit of science, by which the intellect, even though it be not actually considering, is able to consider.

In the second place, this supposition is contrary to the truth. For as the power to act belongs to the same thing as that to which the action belongs, so also the habit belongs to the same thing as that to which the action belongs. But to understand and to consider is the proper act of the intellect. Therefore also the habit by which one considers is properly in the intellect itself.

Replies to objections:

3. To the third it should be said that because the apprehensive powers inwardly prepare their proper objects for the “possible” intellect, therefore it is by the good disposition of these powers, to which the good disposition of the body cooperates, that man is rendered apt to understand. And so in a secondary way an intellective habit can be in these powers. But principally it is in the “possible” intellect.

Article 5

Whether there is any habit in the will

Objections:

It seems that there is not a habit in the will.

1. For the habit which is in the intellect is the intelligible species, by means of which the intellect actually understands. But the will does not act by means of species. Therefore the will is not the subject of a habit.

3. Further, in the natural powers there is no habit because by nature they are determined to one thing. But the will by nature is ordered to tend to the good ordained by reason. Therefore there is no habit in the will.

Response:

It should be said that every power which may be variously directed to act, needs a habit by which it is well disposed to its act. Now since the will is a rational power, it may be variously directed to act. And therefore in the will we must posit the presence of a habit by which it is well disposed to its act....

Replies to objections:

1. To the first, therefore, it should be said that even as in the intellect there is a species which is the likeness of the object, so in the will, and in every appetitive power there must be something by which the power is inclined to its object; for the act of the appetitive power is nothing but a certain inclination, as was said above (q. 6, a. 4; q. 22, a. 2). And therefore with regard to those things to which it is inclined sufficiently by the nature of the power itself, the power needs no quality to incline it. But since it is necessary, for the end of human life, that the appetitive power be inclined to something determinate, to which it is not inclined by the nature of the power, which is open [se habet] to many and various things, therefore it is necessary that, in the will and in the other appetitive powers, there be certain qualities to incline them, and these are called habits.

3. To the third it should be said that the will is by the very nature of the power inclined to the good of the reason. But because this good is varied in many ways, the will needs to be inclined, by means of a habit, to some determinate good of the reason, in order that action may follow more promptly.

Question 51

On the cause of habits

Article 1

Whether any habit is from nature

Objections:

It seems that no habit is from nature.

2. For nature does not do something through two things that it can do through one. But the powers of the soul are from nature. If therefore the habits of the powers were from nature, habit and power would be one.

Response:

It should be said that something can be natural to a thing in two ways. First with regard to the specific nature, as the ability to laugh is natural to man, and it is natural to fire to have an upward tendency. Secondly, with regard to the individual nature, as it is natural to Socrates or Plato to be prone to sickness or inclined to health, in accordance with their respective temperaments. Again, with regard to both natures, something may be called natural in two ways: first, because it entirely is from the nature; secondly, because it is partly from nature, and partly from an extrinsic principle. For example, when a man is healed by himself, his health is entirely from nature; but when a man is healed by means of medicine, health is partly from nature, partly from an extrinsic principle.

Thus, if we speak of habit as a disposition of the subject in relation to form or nature, it may be natural in either of the foregoing ways. For there is a certain natural disposition demanded by the human species, so that no man can be without it. And this disposition is natural with regard to the specific nature. But since such a disposition has a certain latitude, it happens that different grades of this disposition are becoming to different men in respect of the individual nature. And this disposition may be either entirely from nature, or partly from nature, and partly from an extrinsic principle, as we have said of those who are healed by means of art.

But the habit which is a disposition to operation, and whose subject is a power of the soul, as stated above (q. 50, a. 2), may be natural either with regard to the specific nature or with regard to the individual nature: with regard to the specific nature, on the part of the soul itself, which, since it is the form of the body, is the specific principle; but with regard to the individual nature, on the part of the body, which is the material principle. Yet in neither way does it happen that there are natural habits in man in such a way as to be entirely from nature. In the angels indeed this does happen, since they have intelligible species naturally impressed on them, which cannot be said of the human soul, as we have said in the First Part (q. 55, a. 2; q. 84, a. 3).

There are in man, therefore, certain natural habits, owing their existence partly to nature and partly to some extrinsic principle: in one way, indeed, in the apprehensive powers; in another way, in the appetitive powers. For in the apprehensive powers there may be a natural habit by way of a beginning, both with regard to the specific nature, and with regard to the individual nature. This happens with regard to the specific nature, on the part of the soul itself: thus the understanding of first principles is called a natural habit. For it is owing to the very nature of the intellectual soul that man, having once grasped what is a whole and what is a part, should at once perceive that every whole is larger than its part: and in like manner with regard to other such principles. Yet he cannot know what a whole is and what a part is, except through the intelligible species which he has received from phantasms: and for this reason, the Philosopher at the end of the Posterior Analytics shows that knowledge of principles comes to us from the senses.

But with regard to the individual nature, a habit of knowledge is natural as to its beginning, insofar as one man, from the disposition of his organs of sense, is more apt than another to understand well, since we need the sensitive powers for the operation of the intellect.

In the appetitive powers, however, no habit is natural in its beginning, on the part of the soul itself, as to the substance of the habit; but only as to certain principles of it, as for example, the principles of common law are called the seeds of virtue. The reason of this is because the inclination to its proper objects, which seems to be the beginning of a habit, does not belong to the habit, but rather to the very nature of the powers.

But on the part of the body, in respect of the individual nature, there are some appetitive habits by way of natural beginnings. For some are disposed from their own bodily temperament to chastity or meekness or such like.

Replies to objections:

2. To the second it should be said that something may be added even naturally to the nature of a power, which still cannot belong to the power itself. For example, with regard to the angels, it cannot belong to the intellective power itself capable of knowing all things: for thus it would have to be the act of all things, which belongs to God alone. For that by which something is known must be an actual likeness of the thing known; hence, if the power of the angel knew all things by itself, it would follow that it was the likeness and act of all things. Wherefore to the angels’ intellective power must be added some intelligible species, which are likenesses of things understood; for it is by participation of the divine wisdom and not by their own essence that their intellect can be actually those things which they understand. And so it is clear that not everything belonging to a natural habit can belong to the power.

Article 2

Whether any habit is caused by acts

Objections:

It seems that no habit is caused by acts.

1. For habit is a quality, as we have said above (q. 49, a. 1). Now every quality is caused in a subject according to the subject’s receptivity. Therefore since the agent, inasmuch as it acts, does not receive but rather gives, it seems impossible for a habit to be caused in an agent by its own acts.

2. Further, the thing in which a quality is caused is moved to that quality, as may be clearly seen in that which is heated or cooled, whereas that which produces the act that causes the quality, moves it, as may be seen in that which heats or cools. If therefore habits were caused in anything by its own act, it would follow that the same would be mover and moved, active and passive: which is impossible, as stated in Physics III, 8.

3. Further, an effect cannot be nobler than its cause. But a habit is nobler than the act which precedes the habit, as is clear from the fact that the habit produces acts that are nobler than those preceding the habit. Therefore a habit cannot be caused by an act which precedes the habit.

Response:

It should be said that in the agent there is sometimes only the active principle of its act, as in fire there is only the active principle of heating. And in such an agent a habit cannot be caused by its own act; and for this reason natural things cannot become accustomed or unaccustomed, as is said in Ethics II, 1. But a certain agent is found in which there is both an active and a passive principle of its act, as we see in human acts. For the acts of the appetitive power proceed from the appetitive power insofar as it is moved by the apprehensive power presenting the object, and further, the intellective power, insofar as it reasons about conclusions, has as an active principle something that is known of itself. Hence by such acts habits can be caused in their agents, not indeed with regard to the first active principle, but with regard to an active principle that is a moved mover. For everything that is passive and moved by another is disposed by the action of the agent; hence if the acts be multiplied a certain quality is formed in the power which is passive and moved, which quality is called a habit, as the habits of moral virtue are caused in the appetitive powers inasmuch as they are moved by the reason, and as the habits of science are caused in the intellect inasmuch as it is moved by first propositions.

Replies to objections:

1. To the first, therefore, it should be said that the agent, as agent, does not receive anything. But insofar as it moves through being moved by another, it receives something from that which moves it; and thus is a habit caused.

2. To the second it should be said that the same thing cannot be mover and moved in the same respect, but nothing prevents a thing from being moved by itself in different respects, as is proved in Physics VIII, text. 28,29.

3. To the third it should be said that the act which precedes the habit, insofar as it comes from an active principle, proceeds from a more excellent principle than the habit that is caused by it, just as the reason is a more excellent principle than the habit of moral virtue produced in the appetitive power by repeated acts, and as the understanding of first principles is a more excellent principle than the science of conclusions.

Article 4

Whether any habits are infused in man by God

Objections:

It seems that no habit is infused in man by God.

2. For God works in all things according to the mode which is suitable to their nature, for “it belongs to divine providence to preserve nature,” as Dionysius says (On the Divine Names IV). But habits are naturally caused in man by acts, as we have said above (a. 2). Therefore God does not cause habits to be in man except by acts.

3. Further, if any habit be infused into man by God, man can by that habit perform many acts. But “from those acts a like habit is caused” (Ethics II, 1,2). Consequently there will be two habits of the same species in the same man, one acquired, the other infused. Now this seems impossible, for two forms of the same species cannot be in the same subject. Therefore a habit is not infused into man by God.

On the contrary:

It is written (Sirach 15:5): “God filled him with the spirit of wisdom and understanding.” Now wisdom and understanding are habits. Therefore some habits are infused into man by God.

Response:

It should be said that some habits are infused by God into man, for two reasons. The first reason is because there are some habits by which man is disposed to an end which exceeds the proportion of human nature, namely the ultimate and perfect happiness of man, as was said above (q. 5, a. 5). And since habits need to be in proportion with that to which man is disposed by them, those habits that dispose to this end must exceed the proportion of human nature. Wherefore such habits can never be in man except by divine infusion, as is the case with all grace-given virtues.

The other reason is because God can produce the effects of second causes without these second causes, as was said in the First Part (q. 105, a. 6). Just as, therefore, in order to show his power, he sometimes produces health without a natural cause, but which could have been caused by nature, so also, at times, for the manifestation of his power, he infuses into man even those habits which can be caused by a natural power. Thus he gave to the apostles the science of the scriptures and of all tongues, which men can acquire by study or by custom, though not so perfectly.

Replies to objections:

2. To the second it should be said that the fact that God works in all according to their mode does not hinder God from doing what nature cannot do; but it follows from this that he does nothing contrary to that which is suitable to nature.

3. To the third it should be said that acts produced by an infused habit do not cause a habit, but strengthen the already existing habit, just as the remedies of medicine given to a man who is naturally healthy do not cause a kind of health, but give new strength to the health he had before.

Question 52

On the increase of habits

Article 1

Whether habits increase

[Summary of the ways in which habits increase]

Since a habit is not a bodily quantity, an “increase” in a habit refers to becoming more perfect.

A habit can become more perfect in itself, inasmuch as it more wholly or perfectly relates to the nature and act to which it is ordered, as the disposition of health is more perfect to the degree that it more exactly correspond to an animal’s nature, and knowledge is more perfect to the degree that it extends to more things.

A habit can also be more perfectly participated in by its subject, as knowledge or health may be more firmly possessed by one person than by another.

Article 3

Whether every act increases its habit

Response:

It should be said that “like acts cause like habits” (Ethics II, 1,2). Now things are like or unlike not only with respect to having the same or different quality, but also with respect to the same or a different mode of participation. For not only black is unlike white, but also less white is unlike more white, since there is movement from less white to more white, as from one opposite to another, as is said in Physics V, text. 52.

But since use of habits depends on the will, as is evident from what was said above, just as one who has a habit may fail to use it or may act contrary to it, so may he use the habit by performing an act that is not in proportion to the intensity of the habit. Accordingly, if the intensity of the act correspond in proportion to the intensity of the habit, or even surpass it, every such act either increases the habit or disposes to an increase thereof, if we may speak of the increase of habits as we do of the increase of an animal. For not every morsel of food actually increases the animal’s size, as neither does every drop of water hollow out a stone, but the multiplication of food results at last in an increase of the body. So, too, repeated acts cause a habit to grow. If, however, the act falls short of the intensity of the habit, such an act does not dispose to an increase of that habit, but rather to a lessening of it.

Question 53

On the corruption and decrease of habits

Article 3

Whether a habit is corrupted or diminished through mere cessation from act

Response:

It should be said that as is said in Physics VII, text. 27, a thing is a cause of movement in two ways. First, directly; and such a thing causes movement by reason of its proper form; thus fire causes heat. Secondly, indirectly, as that which removes an obstacle. It is in this latter way that the destruction or diminution of a habit results through cessation from act, namely insofar as we cease from exercising an act which overcame the causes that destroy or weaken that habit. For it was said (a. 1) that habits are destroyed or diminished directly through some contrary agent. Consequently all habits that are gradually undermined by contrary agents which need to be counteracted by acts proceeding from those habits, are diminished or even destroyed altogether by long cessation from act, as is clearly seen in the case both of science and of virtue. For it is evident that a habit of moral virtue makes a man ready to choose the mean in deeds and passions. And when a man fails to make use of his virtuous habit in order to moderate his own passions or deeds, the necessary result is that many passions and deeds fail to observe the mode of virtue, by reason of the inclination of the sensitive appetite and of other external things that move one. Wherefore virtue is destroyed or lessened through cessation from act. The same applies to the intellectual habits, which render man ready to judge aright of those things that are pictured by his imagination. Hence when man ceases to make use of his intellectual habits, strange fancies, sometimes in opposition to them, arise in his imagination; so that unless those fancies be as it were cut off or held back by frequent use of his intellectual habits, man becomes less fit to judge aright, and sometimes is even wholly disposed to the contrary, and thus the intellectual habit is diminished or even destroyed by cessation from act.

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