Reply to Objection 1: As stated above (FP, Q[82], A[4]) the will moves all the faculties to their acts. Now the first act of the appetitive faculty is love, as stated above (FS, Q[25], AA[1],2). Accordingly prudence is said to be love, not indeed essentially, but in so far as love moves to the act of prudence. Wherefore Augustine goes on to say that "prudence is love discerning aright that which helps from that which hinders us in tending to God." Now love is said to discern because it moves the reason to discern.
Reply to Objection 2: The prudent man considers things afar off, in so far as they tend to be a help or a hindrance to that which has to be done at the present time. Hence it is clear that those things which prudence considers stand in relation to this other, as in relation to the end. Now of those things that are directed to the end there is counsel in the reason, and choice in the appetite, of which two, counsel belongs more properly to prudence, since the Philosopher states (Ethic. vi, 5,7,9) that a prudent man "takes good counsel." But as choice presupposes counsel, since it is "the desire for what has been already counselled" (Ethic. iii, 2), it follows that choice can also be ascribed to prudence indirectly, in so far, to wit, as prudence directs the choice by means of counsel.
Reply to Objection 3: The worth of prudence consists not in thought merely, but in its application to action, which is the end of the practical reason. Wherefore if any defect occur in this, it is most contrary to prudence, since, the end being of most import in everything, it follows that a defect which touches the end is the worst of all. Hence the Philosopher goes on to say (Ethic. vi, 5) that prudence is "something more than a merely rational habit," such as art is, since, as stated above (FS, Q[57] , A[4]) it includes application to action, which application is an act of the will.
Whether prudence belongs to the practical reason alone or also to the speculative reason?
Objection 1: It would seem that prudence belongs not only to the practical, but also to the speculative reason. For it is written ( Prov. 10:23 ): "Wisdom is prudence to a man." Now wisdom consists chiefly in contemplation. Therefore prudence does also.
Objection 2: Further, Ambrose says (De Offic. i, 24): "Prudence is concerned with the quest of truth, and fills us with the desire of fuller knowledge." Now this belongs to the speculative reason. Therefore prudence resides also in the speculative reason.
Objection 3: Further, the Philosopher assigns art and prudence to the same part of the soul (Ethic. vi, 1). Now art may be not only practical but also speculative, as in the case of the liberal arts. Therefore prudence also is both practical and speculative.
On the contrary, The Philosopher says (Ethic. vi, 5) that prudence is right reason applied to action. Now this belongs to none but the practical reason. Therefore prudence is in the practical reason only.
I answer that, According to the Philosopher (Ethic. vi, 5) "a prudent man is one who is capable of taking good counsel." Now counsel is about things that we have to do in relation to some end: and the reason that deals with things to be done for an end is the practical reason. Hence it is evident that prudence resides only in the practical reason.
Reply to Objection 1: As stated above (Q[45], AA[1],3), wisdom considers the absolutely highest cause: so that the consideration of the highest cause in any particular genus belongs to wisdom in that genus. Now in the genus of human acts the highest cause is the common end of all human life, and it is this end that prudence intends. For the Philosopher says (Ethic. vi, 5) that just as he who reasons well for the realization of a particular end, such as victory, is said to be prudent, not absolutely, but in a particular genus, namely warfare, so he that reasons well with regard to right conduct as a whole, is said to be prudent absolutely. Wherefore it is clear that prudence is wisdom about human affairs: but not wisdom absolutely, because it is not about the absolutely highest cause, for it is about human good, and this is not the best thing of all. And so it is stated significantly that "prudence is wisdom for man," but not wisdom absolutely.
Reply to Objection 2: Ambrose, and Tully also (De Invent. ii, 53) take the word prudence in a broad sense for any human knowledge, whether speculative or practical. And yet it may also be replied that the act itself of the speculative reason, in so far as it is voluntary, is a matter of choice and counsel as to its exercise; and consequently comes under the direction of prudence. On the other hand, as regards its specification in relation to its object which is the "necessary true," it comes under neither counsel nor prudence.
Reply to Objection 3: Every application of right reason in the work of production belongs to art: but to prudence belongs only the application of right reason in matters of counsel, which are those wherein there is no fixed way of obtaining the end, as stated in Ethic. iii, 3. Since then, the speculative reason makes things such as syllogisms, propositions and the like, wherein the process follows certain and fixed rules, consequently in respect of such things it is possible to have the essentials of art, but not of prudence; and so we find such a thing as a speculative art, but not a speculative prudence.
Whether prudence takes cognizance of singulars?
Objection 1: It would seem that prudence does not take cognizance of singulars. For prudence is in the reason, as stated above (AA[1],2). But "reason deals with universals," according to Phys. i, 5. Therefore prudence does not take cognizance except of universals.
Objection 2: Further, singulars are infinite in number. But the reason cannot comprehend an infinite number of things. Therefore prudence which is right reason, is not about singulars.
Objection 3: Further, particulars are known by the senses. But prudence is not in a sense, for many persons who have keen outward senses are devoid of prudence. Therefore prudence does not take cognizance of singulars.
On the contrary, The Philosopher says (Ethic. vi, 7) that "prudence does not deal with universals only, but needs to take cognizance of singulars also."
I answer that, As stated above (A[1], ad 3), to prudence belongs not only the consideration of the reason, but also the application to action, which is the end of the practical reason. But no man can conveniently apply one thing to another, unless he knows both the thing to be applied, and the thing to which it has to be applied. Now actions are in singular matters: and so it is necessary for the prudent man to know both the universal principles of reason, and the singulars about which actions are concerned.
Reply to Objection 1: Reason first and chiefly is concerned with universals, and yet it is able to apply universal rules to particular cases: hence the conclusions of syllogisms are not only universal, but also particular, because the intellect by a kind of reflection extends to matter, as stated in De Anima iii.
Reply to Objection 2: It is because the infinite number of singulars cannot be comprehended by human reason, that "our counsels are uncertain" ( Wis. 9:14 ). Nevertheless experience reduces the infinity of singulars to a certain finite number which occur as a general rule, and the knowledge of these suffices for human prudence.
Reply to Objection 3: As the Philosopher says (Ethic. vi, 8), prudence does not reside in the external senses whereby we know sensible objects, but in the interior sense, which is perfected by memory and experience so as to judge promptly of particular cases. This does not mean however that prudence is in the interior sense as in its principle subject, for it is chiefly in the reason, yet by a kind of application it extends to this sense.
Whether prudence is a virtue?
Objection 1: It would seem that prudence is not a virtue. For Augustine says (De Lib. Arb. i, 13) that "prudence is the science of what to desire and what to avoid." Now science is condivided with virtue, as appears in the Predicaments (vi). Therefore prudence is not a virtue.
Objection 2: Further, there is no virtue of a virtue: but "there is a virtue of art," as the Philosopher states (Ethic. vi, 5): wherefore art is not a virtue. Now there is prudence in art, for it is written (2 Paralip. ii, 14) concerning Hiram, that he knew "to grave all sort of graving, and to devise ingeniously [prudenter] all that there may be need of in the work." Therefore prudence is not a virtue.
Objection 3: Further, no virtue can be immoderate. But prudence is immoderate, else it would be useless to say ( Prov. 23:4 ): "Set bounds to thy prudence." Therefore prudence is not a virtue.