Lecture 1 — Right Reason

But, since we previously said that we ought to choose a mean, rejecting excess and defect, and that the mean is determined according to right reason, we may now make a division of right reason. [1109]

In all habits previously considered and in other matters, there is some mark on which the man who possesses right reason keeps his eye, straining and relaxing; and this is the limit of the middle courses that we say are means between excesses and defects in accord with right reason. [1110]

It is true indeed to say this, but nothing is made clear by it. In all occupations in which science is at work, it is true to say that neither too much nor too little ought to be done or omitted, but rather what is moderate and as reason determines. But a man possessing only this knowledge will not know how to proceed further, such as in what remedies must be given for the body, if someone suggests that it should be whatever medical art, as possessed by the doctor, prescribes. [1111]

For this reason, this true statement be made about not only the habits of the soul but also the nature of right reason and its limits must be determined. [1112]

We have, however, already divided the virtues of the soul, stating that some are moral and others intellectual. The moral virtues we have discussed, and the others we will now treat, after first speaking of the soul. [1113]

We said before that there are two parts of the soul: rational and irrational. [1114]

Now we will speak of the rational part in the same way. Let us suppose two parts of the rational soul: one by which we consider the kind of things whose principles cannot be otherwise and another by which we consider contingent things. [1115]

To the objects, which differ in kind, correspond different kinds of parts of the soul, since indeed the knowledge of the objects exists (in the parts) according to a certain species and reality. [1116–17]

Let one of these be called scientific but the other estimative, for deliberating and estimating are the same. No one deliberates about things that do not take place any other way. Therefore, the estimative element is one part of the rational soul. [1118]

1109. But, since we previously said. After the Philosopher has completed the explanation of the moral virtues, he begins in book 6 to explain the intellectual virtues.

First, by way of introduction, he speaks of what he proposes.

Second, at we said before (1139a3; [1114]), he explains his proposition.

On the first point, he does three things.

First, he states that we must discuss right reason.

Second, at in all habits previously considered (1138b21; [1110]), he shows what we must discuss about it.

Third, at we have, however, already divided (1138b35; [1113]), he continues with what precedes.

He says first that it was stated before [317] that we must choose a mean and reject excess and defect in the moral virtues that we have just discussed [245–1108], and that the mean is determined according to right reason, as was decided in the book 2 [322]. Consequently, we should divide right reason, an intellectual virtue that is rectitude of the reason, into its species, as in a similar fashion we have already divided the moral virtues.

1110. Then, at in all habits previously considered (1138b21), he shows what has to be discussed about right reason.

On this point, he does three things.

First, he shows what can be understood from the things that were said before.

Second, at it is true indeed (1138b25; [1111]), he discloses that this is not sufficient.

Third, at for this reason (1138b32; [1112]), he infers what should be added.

He says first that, in all habits previously considered, meaning the moral virtues, as in other things such as the artistic, there is an object (a mark, as it were) on which the man with right reason keeps his eye; and according to this, he strives and makes modifications (that is, he adds or subtracts), or considers by this mark what the limit of the middle course is and how it ought to be ascertained in each virtue. We say that such a middle course is a certain mean between excess and defect, and in accord with right reason. This mark, holding for the virtuous man the place of a rule for the craftsman, is what is becoming and fitting, that which we must not fall short of or add to; this is the mean of virtue. These matters have been clarified in the book 2 [327].

1111. Next, at it is true (1138b25), he shows that it is not enough to know this about right reason. He states that what was said [1110] is certainly true but does not make sufficiently clear what is required for the use of right reason; it is something common verified in all human occupations in which men operate according to a practical science, such as in strategy, medicine, and the various professions. In all these, it is true to say that neither too much nor too little ought to be done or omitted, but rather what holds the middle and is in accord with what right reason determines. But the man who considers the common feature alone will not know how to proceed to action by reason of this generality. If a person were to ask what ought to be given to restore bodily health and someone advised him to give what is prescribed by medical art and by one who has this art—namely, a doctor—the interrogator would not know from such information what medicine the sick man needs. But as the right plan of prudence is the guide in moral matters, so the right plan of art is the guide in art. Hence, it is evident that the principle discussed is insufficient.

1112. At for this reason (1138b32), he concludes by like reasoning that a general statement on the soul’s habits is insufficient, but the limits of right reason and its norm (that is, a definition of right reason, or, also, according to what right reason can be determined) must be distinctly determined.

1113. Then, at we have, however, already divided (1138b35), he continues, with a previous discussion. He says that, in making the division at the end of book 1 [234], we spoke of the virtues of the soul as being either intellectual or moral. Since we have completed the investigation of the moral virtues [245–1108], it remains for us to examine the intellectual virtues in accord with which reason itself is regulated, prefacing this with a discussion of certain things about the soul (for, without this knowledge, the virtues of the soul cannot be known), as was noted previously at the end of book 1 [228].

1114. Next, at we said before (1139a3), he begins to follow up his proposition.

First, he explains what is to be discussed about the soul.

Second, at we must, then (1139a17; [1124]), he pursues the intellectual virtues.

On the first point, he does three things.

First, he resumes the division of the parts of the soul given previously at the end of book 1.

Second, at now we will (1139a5; [1115]), he subdivides one member.

He says first that it was previously stated that there are two parts of the soul: one is rational and the other irrational. It has been explained before [243] that the part that is essentially rational is perfected by the intellectual virtues. But the irrational part (which, however, participates in rationality) is perfected by the moral virtues.

1115. At now we will (1139a5), he subdivides one member of this division.

On this point, he does three things.

First, he proposes the division.

Second, at to the objects, which differ (1139a8; [1116]), he explains the members of the division.

Third, at let one of these be called (1139a11; [1118]), he names the members of the division.

He says first that, since we have in mind the intellectual virtues that perfect the rational part of the soul, in order to distinguish the intellectual virtues, we must divide the rational part in the same way as we have previously divided the parts of the soul [229], not by reason of its principal aspect, as it were, but in a way sufficient for our purpose.

Let us suppose, then, that the organ of reason is divided into two parts:

one by which we consider those necessary things whose principles cannot be otherwise;

the other by which we consider contingent things.

1116. Then, at to the objects, which differ (1139a8), he explains the aforementioned division by this reasoning. It is necessary that different kinds of parts of the soul should correspond to objects differing in kind. But obviously the contingent and the necessary differ in kind, as is noted concerning the corruptible and incorruptible in Metaphysics 10. (Metaphysics 10.10.1058b26–1059a14; see Aquinas, In X metaph., lec. 12 [2136–45].) Therefore, we conclude that, by a differentiation of parts, the rational soul knows necessary and contingent things.

1117. Next, at since indeed (1139a8), he explains the major proposition in this way. Knowledge exists in parts of the soul according as they have a certain likeness to the things known. We do not mean by this that the thing actually known is in the substance of the knowing faculty (as Empedocles held, saying that we know earth by earth, fire by fire, and so on), but rather inasmuch as each power of the soul is proportioned according to its peculiar nature to know objects of this kind, as sight to see color and hearing to perceive sound. But, in things that are similar and proportioned to one another, the same reason for distinction exists. Therefore, as the things known by reason differ in kind, so also the parts of the rational soul differ.

1118. At let one of these be called (1139a11), he names the aforementioned parts. He says that, of these parts of the rational soul, the one that considers necessary things may be called the scientific kind of soul because its knowledge is of the necessary. But another part may be called the estimative kind, according as estimating and deliberating are taken for the same thing. He calls deliberation a certain inquiry not yet concluded, like argumentation. This indetermination of mind happens especially in regard to contingent things, which are the only subjects of deliberation, for no one deliberates about things that take place in one fixed mode. So, then, it follows that the estimative element is one part of the rational soul.

1119. What the Philosopher here determines seems to be doubtful. In De anima, (Bk. 3, c. 4, 429a10 sq.; St. Th. Lect. 7, 671 sq.) he divides the intellect into two parts: the active and the potential. He says that the active intellect is the power of operating on all things and the potential is the power of becoming all things. So, then, both the active intellect and the potential, by their very nature, are in touch with all things. Therefore, it would be contrary to the nature of each intellect if there was one part of the soul that understood necessary things and another that understood contingent things.

1120. Again, the true in necessary matter and the true in contingent matter resemble perfect and imperfect in the genus of what is true. But, by the same power of the soul, we know both perfect and imperfect things of the same genus; for example, sight perceives bright and dark objects. Much more, then, the same intellective power knows necessary and contingent things.

1121. Likewise, the intellect touches intelligible objects in a more universal way than the senses touch sensible objects. Now, the nobler the power, the more united is its activity. But the sense of sight shares in both incorruptible bodies and corruptible bodies, to which the necessary and contingent proportionately correspond. For a far greater reason, then, the intellective power knows both necessary and contingent.

1122. Moreover, the proof that he presents does not seem to be convincing. Not every difference in the classification of the object requires different powers (otherwise we would not see plants and other animals by the same power of sight), but rather that difference regarding the formal reason of the object. For instance, if there were a different genus of color or light, there would have to be different powers of sight. But the proper object of the intellect is that which exists, something common to all substances and accidents, although not in the same way. Hence, we know both substances and accidents by the same intellective power. Therefore, by the same token, the difference in the classification of necessary and contingent things does not require different intellective powers.

1123. This doubt is easily solved by considering that contingent things can be understood in two ways:

in one way according to their universal concepts;

in the other way as they are in the concrete.

Accordingly, the universal concepts of contingent things are immutable. In this way, demonstrations are given about contingent things, and the knowledge of them belongs to the demonstrative sciences. Natural science is concerned not only with necessary and incorruptible things but also with corruptible and contingent things.

Hence, it is evident that contingent things considered in this way belong to the same part of the intellective soul (called scientific by the Philosopher) as do necessary things, and the reasons presented proceed with this understanding.

In the other way, contingent things can be taken as they are in the real order. Thus understood, they are variable and do not fall under the intellect except by means of the sensitive powers. Thus, among the parts of the sensitive soul we place a power called particular reason or the sensory power of judgment, which collates particular impressions. It is in this sense that the Philosopher here understands contingent things, for thus they are objects of counsel and operation. For this reason, he says that necessary and contingent things, like speculative universals and individual operable things, belong to different parts of the rational soul.