Nicomachean Ethics by Aristotle — Book VI, The five intellectual virtues

We have already said that it is right to choose the mean and to avoid excess and deficiency, and that the mean is prescribed by the right principle. Let us now analyze the latter notion.

In the case of each of the moral qualities or dispositions that have been discussed, as with all the other virtues also, there is a certain mark to aim at, on which the man who knows the principle involved fixes his gaze, and increases or relaxes the tension accordingly; there is a certain standard determining those modes of observing the mean which we define as lying between excess and defect, being in conformity with the right principle.

This bare statement however, although true, is not at all enlightening. In all departments of human endeavor that have been reduced to a science, it is true to say that effort ought to be exerted and relaxed neither too much nor too little, but to the medium amount, and as the right principle decides. Yet a person knowing this truth will be no wiser than before: for example, he will not know what medicines to take merely from being told to take everything that medical science or a medical expert would prescribe.

Hence with respect to the qualities of the soul also, it is not enough merely to have established the truth of the above formula; we also have to define exactly what the right principle is, and what is the standard that determines it.

Now we have divided the Virtues of the Soul into two groups, ^1139.1the Virtues of the Character and the Virtues of the Intellect. The former, the Moral Virtues, we have already discussed. Our account of the latter must be prefaced by some remarks about psychology.

It has been said before that the soul has two parts, one rational and the other irrational. Let us now similarly divide the rational part, and let it be assumed that there are two rational faculties, one whereby we contemplate those things whose first principles are invariable, and one whereby we contemplate those things which admit of variation: since, on the assumption that knowledge is based on a likeness or affinity of some sort between subject and object, the parts of the soul adapted to the cognition of objects that are of different kinds must themselves differ in kind.

These two rational faculties may be designated the Scientific Faculty and the Calculative Faculty respectively; since calculation is the same as deliberation, and deliberation is never exercised about things that are invariable, so that the Calculative Faculty is a separate part of the rational half of the soul.

We have therefore to ascertain what disposition of each of these faculties is the best, for that will be the special virtue of each.

But the virtue of a faculty is related to the special function which that faculty performs.

Now there are three elements in the soul which control action and the attainment of truth: namely, Sensation, Intellect, and Desire.

Of these, Sensation never originates action, as is shown by the fact that animals have sensation but are not capable of action.

Pursuit and avoidance in the sphere of Desire correspond to affirmation and denial in the sphere of the Intellect. Hence inasmuch as moral virtue is a disposition of the mind in regard to choice, and choice is deliberate desire, it follows that, if the choice is to be good, both the principle must be true and the desire right, and that desire must pursue the same things as principle affirms.

We are here speaking of practical thinking, and of the attainment of truth in regard to action; with speculative thought, which is not concerned with action or production, right and wrong functioning consist in the attainment of truth and falsehood respectively. The attainment of truth is indeed the function of every part of the intellect, but that of the practical intelligence is the attainment of truth corresponding to right desire.

Now the cause of action (the efficient, not the final cause) is choice, and the cause of choice is desire and reasoning directed to some end. Hence choice necessarily involves both intellect or thought and a certain disposition of character for doing well and the reverse in the sphere of action necessarily involve thought and character.

Thought by itself however moves nothing, but only thought directed to an end, and dealing with action. ^1139.2This indeed is the moving cause of productive activity also, since he who makes some thing always has some further end in view: the act of making is not an end in itself, it is only a means, and belongs to something else. Whereas a thing done is an end in itself: since doing well (welfare) is the End, and it is at this that desire aims.

Hence Choice may be called either thought related to desire or desire related to thought; and man, as an originator of action, is a union of desire and intellect.

(Choice is not concerned with what has happened already: for example, no one chooses to have sacked Troy; for neither does one deliberate about what has happened in the past, but about what still lies in the future and may happen or not; what has happened cannot be made not to have happened. Hence Agathon is right in saying This only is denied even to God, The power to make what has been done undone.) The attainment of truth is then the function of both the intellectual parts of the soul. Therefore their respective virtues are those dispositions which will best qualify them to attain truth.

Let us then discuss these virtues afresh, going more deeply into the matter.

Let it be assumed that there are five qualities through which the mind achieves truth in affirmation or denial, namely Art or technical skill, Scientific Knowledge, Prudence, Wisdom, and Intelligence. Conception and Opinion are capable of error.

The nature of Scientific Knowledge (employing the term in its exact sense and disregarding its analogous uses) may be made clear as follows. We all conceive that a thing which we know scientifically cannot vary; when a thing that can vary is beyond the range of our observation, we do not know whether it exists or not. An object of Scientific Knowledge, therefore, exists of necessity. It is therefore eternal, for everything existing of absolute necessity is eternal; and what is eternal does not come into existence or perish.

Again, it is held that all Scientific Knowledge can be communicated by teaching, and that what is scientifically known must be learnt. But all teaching starts from facts previously known, as we state in the Analytics, since it proceeds either by way of induction, or else by way of deduction. Now induction supplies a first principle or universal, deduction works from universals; therefore there are first principles from which deduction starts, which cannot be proved by deduction; therefore they are reached by induction.

Scientific Knowledge, therefore, is the quality whereby we demonstrate, with the further qualifications included in our definition of it in the Analytics, namely, that a man knows a thing scientifically when he possesses a conviction arrived at in a certain way, and when the first principles on which that conviction rests are known to him with certainty—for unless he is more certain of his first principles than of the conclusion drawn from them he will only possess the knowledge in question accidentally. Let this stand as our definition of Scientific Knowledge.

^1140.1The class of things that admit of variation includes both things made and actions done.

But making is different from doing (a distinction we may accept from extraneous discourses). Hence the rational quality concerned with doing is different from the rational quality concerned with making; nor is one of them a part of the other, for doing is not a form of making, nor making a form of doing.

Now architectural skill, for instance, is an art, and it is also a rational quality concerned with making; nor is there any art which is not a rational quality concerned with making, nor any such quality which is not an art. It follows that an art is the same thing as a rational quality, concerned with making, that reasons truly.

All Art deals with bringing some thing into existence; and to pursue an art means to study how to bring into existence a thing which may either exist or not, and the efficient cause of which lies in the maker and not in the thing made; for Art does not deal with things that exist or come into existence of necessity, or according to nature, since these have their efficient cause in themselves.

But as doing and making are distinct, it follows that Art, being concerned with making, is not concerned with doing. And in a sense Art deals with the same objects as chance, as Agathon says: Chance is beloved of Art, and Art of Chance.

Art, therefore, as has been said, is a rational quality, concerned with making, that reasons truly. Its opposite, Lack of Art, is a rational quality, concerned with making, that reasons falsely. Both deal with that which admits of variation.

We may arrive at a definition of Prudence by considering who are the persons whom we call prudent. Now it is held to be the mark of a prudent man to be able to deliberate well about what is good and advantageous for himself, not in some one department, for instance what is good for his health or strength, but what is advantageous as a means to the good life in general.

This is proved by the fact that we also speak of people as prudent or wise in some particular thing, when they calculate well with a view to attaining some particular end of value (other than those ends which are the object of an art); so that the prudent man in general will be the man who is good at deliberating in general.

But no one deliberates about things that cannot vary, nor about things not within his power to do. Hence inasmuch as scientific knowledge involves demonstration, whereas things whose fundamental principles are variable are not capable of demonstration, because everything about them is variable, ^1140.2and inasmuch as one cannot deliberate about things that are of necessity, it follows that Prudence is not the same as Science. Nor can it be the same as Art. It is not Science, because matters of conduct admit of variation; and not Art, because doing and making are generically different, since making aims at an end distinct from the act of making, whereas in doing the end cannot be other than the act itself: doing well is in itself the end.

It remains therefore that it is a truth-attaining rational quality, concerned with action in relation to things that are good and bad for human beings.

Hence men like Pericles are deemed prudent, because they possess a faculty of discerning what things are good for themselves and for mankind and that is our conception of an expert in Domestic Economy or Political Science.

(This also accounts for the word Temperance, which signifies preserving prudence.

And Temperance does in fact preserve our belief as to our own good; for pleasure and pain do not destroy or pervert all beliefs, for instance, the belief that the three angles of a triangle are, or are not, together equal to two right angles, but only beliefs concerning action. The first principles of action are the end to which our acts are means; but a man corrupted by a love of pleasure or fear of pain, entirely fails to discern any first principle, and cannot see that he ought to choose and do everything as a means to this end, and for its sake; for vice tends to destroy the sense of principle.)

It therefore follows that Prudence is a truth-attaining rational quality, concerned with action in relation to the things that are good for human beings.

Moreover, we can speak of excellence in Art, but not of excellence in Prudence. Also in Art voluntary error is not so bad as involuntary, whereas in the sphere of Prudence it is worse, as it is in the sphere of the virtues. It is therefore clear that Prudence is an excellence or virtue, and not an Art.

Of the two parts of the soul possessed of reason, Prudence must be the virtue of one, namely, the part that forms opinions; for Opinion deals with that which can vary, and so does Prudence. But yet Prudence is not a rational quality merely, as shown by the fact that a purely rational faculty can be forgotten, whereas a failure in Prudence is not a mere lapse of memory.

Scientific Knowledge is a mode of conception dealing with universals and things that are of necessity; and demonstrated truths and all scientific knowledge (since this involves reasoning) are derived from first principles. Consequently the first principles from which scientific truths are derived cannot themselves be reached by Science; nor yet are they apprehended by Art, nor by Prudence. To be matter of Scientific Knowledge a truth must be demonstrated by deduction from other truths; ^1141.1while Art and Prudence are concerned only with things that admit of variation. Nor is Wisdom the knowledge of first principles either: for the philosopher has to arrive at some things by demonstration.