Summa Th. II-II EN Qu.47 a.14
Objection: 1. It would seem that prudence is not in all who have grace. Prudence requires diligence, that one may foresee aright what has to be done. But many who have grace have not this diligence. Therefore not all who have grace have prudence.
2. Further, a prudent man is one who takes good counsel, as stated above (Article [8], Objection [2]; Article [13], Objection [3]). Yet many have grace who do not take good counsel, and need to be guided by the counsel of others. Therefore not all who have grace, have prudence
3. Further, the Philosopher says (Topic. iii, 2) that "young people are not obviously prudent." Yet many young people have grace. Therefore prudence is not to be found in all who have grace.
On the contrary No man has grace unless he be virtuous. Now no man can be virtuous without prudence, for Gregory says (Moral. ii, 46) that "the other virtues cannot be virtues at all unless they effect prudently what they desire to accomplish." Therefore all who have grace have prudence.
I answer that The virtues must needs be connected together, so that whoever has one has all, as stated above (FS, Question [65], Article [1]). Now whoever has grace has charity, so that he must needs have all the other virtues, and hence, since prudence is a virtue, as shown above (Article [4]), he must, of necessity, have prudence also.
Reply to Objection: 1. Diligence is twofold: one is merely sufficient with regard to things necessary for salvation; and such diligence is given to all who have grace, whom "His unction teacheth of all things" (1Jn 2,27). There is also another diligence which is more than sufficient, whereby a man is able to make provision both for himself and for others, not only in matters necessary for salvation, but also in all things relating to human life; and such diligence as this is not in all who have grace.
2. Those who require to be guided by the counsel of others, are able, if they have grace, to take counsel for themselves in this point at least, that they require the counsel of others and can discern good from evil counsel.
3. Acquired prudence is caused by the exercise of acts, wherefore "its acquisition demands experience and time" (Ethic. ii, 1), hence it cannot be in the young, neither in habit nor in act. On the other hand gratuitous prudence is caused by divine infusion. Wherefore, in children who have been baptized but have not come to the use of reason, there is prudence as to habit but not as to act, even as in idiots; whereas in those who have come to the use of reason, it is also as to act, with regard to things necessary for salvation. This by practice merits increase, until it becomes perfect, even as the other virtues. Hence the Apostle says (He 5,14) that "strong meat is for the perfect, for them who by custom have their senses exercised to the discerning of good and evil."
Objection: 1. It would seem that prudence is in us by nature. The Philosopher says that things connected with prudence "seem to be natural," namely "synesis, gnome" [*(synesis) and (gnome), Cf. FS, Question [57], Article [6]] and the like, but not those which are connected with speculative wisdom. Now things belonging to the same genus have the same kind of origin. Therefore prudence also is in us from nature.
2. Further, the changes of age are according to nature. Now prudence results from age, according to Jb 12,12: "In the ancient is wisdom, and in length of days prudence." Therefore prudence is natural.
3. Further, prudence is more consistent with human nature than with that of dumb animals. Now there are instances of a certain natural prudence in dumb animals, according to the Philosopher (De Hist. Anim. viii, 1). Therefore prudence is natural.
On the contrary The Philosopher says (Ethic. ii, 1) that "intellectual virtue is both originated and fostered by teaching; it therefore demands experience and time." Now prudence is an intellectual virtue, as stated above (Article [4]). Therefore prudence is in us, not by nature, but by teaching and experience.
I answer that As shown above (Article [3]), prudence includes knowledge both of universals, and of the singular matters of action to which prudence applies the universal principles. Accordingly, as regards the knowledge of universals, the same is to be said of prudence as of speculative science, because the primary universal principles of either are known naturally, as shown above (Article [6]): except that the common principles of prudence are more connatural to man; for as the Philosopher remarks (Ethic. x, 7) "the life which is according to the speculative reason is better than that which is according to man": whereas the secondary universal principles, whether of the speculative or of the practical reason, are not inherited from nature, but are acquired by discovery through experience, or through teaching.On the other hand, as regards the knowledge of particulars which are the matter of action, we must make a further distinction, because this matter of action is either an end or the means to an end. Now the right ends of human life are fixed; wherefore there can be a natural inclination in respect of these ends; thus it has been stated above (FS, Question [51], Article [1]; FS, Question [63], Article [1]) that some, from a natural inclination, have certain virtues whereby they are inclined to right ends; and consequently they also have naturally a right judgment about such like ends.But the means to the end, in human concerns, far from being fixed, are of manifold variety according to the variety of persons and affairs. Wherefore since the inclination of nature is ever to something fixed, the knowledge of those means cannot be in man naturally, although, by reason of his natural disposition, one man has a greater aptitude than another in discerning them, just as it happens with regard to the conclusions of speculative sciences. Since then prudence is not about the ends, but about the means, as stated above (Article [6]; FS, Question [57], Article [5]), it follows that prudence is not from nature.
Reply to Objection: 1. The Philosopher is speaking there of things relating to prudence, in so far as they are directed to ends. Wherefore he had said before (Ethic. vi, 5,11) that "they are the principles of the (ou heneka)" [*Literally, 'for the sake of which' (are the means)], namely, the end; and so he does not mention (euboulia) among them, because it takes counsel about the means.
2. Prudence is rather in the old, not only because their natural disposition calms the movement of the sensitive passions, but also because of their long experience.
3. Even in dumb animals there are fixed ways of obtaining an end, wherefore we observe that all the animals of a same species act in like manner. But this is impossible in man, on account of his reason, which takes cognizance of universals, and consequently extends to an infinity of singulars.
Objection: 1. It would seem that prudence can be lost through forgetfulness. For since science is about necessary things, it is more certain than prudence which is about contingent matters of action. But science is lost by forgetfulness. Much more therefore is prudence.
2. Further, as the Philosopher says (Ethic. ii, 3) "the same things, but by a contrary process, engender and corrupt virtue." Now the engendering of prudence requires experience which is made up "of many memories," as he states at the beginning of his Metaphysics (i, 1). Therefore since forgetfulness is contrary to memory, it seems that prudence can be lost through forgetfulness.
3. Further, there is no prudence without knowledge of universals. But knowledge of universals can be lost through forgetfulness. Therefore prudence can also.
On the contrary The Philosopher says (Ethic. vi, 5) that "forgetfulness is possible to art but not to prudence."
I answer that Forgetfulness regards knowledge only, wherefore one can forget art and science, so as to lose them altogether, because they belong to the reason. But prudence consists not in knowledge alone, but also in an act of the appetite, because as stated above (Article [8]), its principal act is one of command, whereby a man applies the knowledge he has, to the purpose of appetition and operation. Hence prudence is not taken away directly by forgetfulness, but rather is corrupted by the passions. For the Philosopher says (Ethic. vi, 5) that "pleasure and sorrow pervert the estimate of prudence": wherefore it is written (Da 13,56): "Beauty hath deceived thee, and lust hath subverted thy heart," and (Ex 23,8): "Neither shalt thou take bribes which blind even the prudent [Douay: 'wise']."Nevertheless forgetfulness may hinder prudence, in so far as the latter's command depends on knowledge which may be forgotten.
Reply to Objection: 1. Science is in the reason only: hence the comparison fails, as stated above [*Cf. FS, Question [53], Article [1]].
2. The experience required by prudence results not from memory alone, but also from the practice of commanding aright.
3. Prudence consists chiefly, not in the knowledge of universals, but in applying them to action, as stated above (Article [3]). Wherefore forgetting the knowledge of universals does not destroy the principal part of prudence, but hinders it somewhat, as stated above.
We must now consider the parts of prudence, under which head there are four points of inquiry:
(1) Which are the parts of prudence?
(2) Of its integral parts;
(3) Of its subjective parts;
(4) Of its potential parts.
Objection: 1. It would seem that the parts of prudence are assigned unfittingly. Tully (De Invent. Rhet. ii, 53) assigns three parts of prudence, namely, "memory," "understanding" and "foresight." Macrobius (In Somn. Scip. i) following the opinion of Plotinus ascribes to prudence six parts, namely, "reasoning," "understanding," "circumspection," "foresight," "docility" and "caution." Aristotle says (Ethic. vi, 9,10,11) that "good counsel," "synesis" and "gnome" belong to prudence. Again under the head of prudence he mentions "conjecture," "shrewdness," "sense" and "understanding." And another Greek philosopher [*Andronicus; Cf. Question [80], Objection [4]] says that ten things are connected with prudence, namely, "good counsel," "shrewdness," "foresight," "regnative [*Regnativa]," "military," "political" and "domestic prudence," "dialectics," "rhetoric" and "physics." Therefore it seems that one or the other enumeration is either excessive or deficient.
2. Further, prudence is specifically distinct from science. But politics, economics, logic, rhetoric, physics are sciences. Therefore they are not parts of prudence.
3. Further, the parts do not exceed the whole. Now the intellective memory or intelligence, reason, sense and docility, belong not only to prudence but also to all the cognitive habits. Therefore they should not be set down as parts of prudence.
4. Further, just as counselling, judging and commanding are acts of the practical reason, so also is using, as stated above (FS, Question [16], Article [1]). Therefore, just as "eubulia" which refers to counsel, is connected with prudence, and "synesis" and "gnome" which refer to judgment, so also ought something to have been assigned corresponding to use.
5. Further, solicitude pertains to prudence, as stated above (Question [47], Article [9]). Therefore solicitude also should have been mentioned among the parts of prudence.
I answer that Parts are of three kinds, namely, "integral," as wall, roof, and foundations are parts of a house; "subjective," as ox and lion are parts of animal; and "potential," as the nutritive and sensitive powers are parts of the soul. Accordingly, parts can be assigned to a virtue in three ways. First, in likeness to integral parts, so that the things which need to concur for the perfect act of a virtue, are called the parts of that virtue. In this way, out of all the things mentioned above, eight may be taken as parts of prudence, namely, the six assigned by Macrobius; with the addition of a seventh, viz. "memory" mentioned by Tully; and (eustochia) or "shrewdness" mentioned by Aristotle. For the "sense" of prudence is also called "understanding": wherefore the Philosopher says (Ethic. vi, 11): "Of such things one needs to have the sense, and this is understanding." Of these eight, five belong to prudence as a cognitive virtue, namely, "memory," "reasoning," "understanding," "docility" and "shrewdness": while the three others belong thereto, as commanding and applying knowledge to action, namely, "foresight," "circumspection" and "caution." The reason of their difference is seen from the fact that three things may be observed in reference to knowledge. In the first place, knowledge itself, which, if it be of the past, is called "memory," if of the present, whether contingent or necessary, is called "understanding" or "intelligence." Secondly, the acquiring of knowledge, which is caused either by teaching, to which pertains "docility," or by "discovery," and to this belongs to (eustochia), i.e. "a happy conjecture," of which "shrewdness" is a part, which is a "quick conjecture of the middle term," as stated in Poster. i, 9. Thirdly, the use of knowledge, in as much as we proceed from things known to knowledge or judgment of other things, and this belongs to "reasoning." And the reason, in order to command aright, requires to have three conditions. First, to order that which is befitting the end, and this belongs to "foresight"; secondly, to attend to the circumstances of the matter in hand, and this belongs to "circumspection"; thirdly, to avoid obstacles, and this belongs to "caution."The subjective parts of a virtue are its various species. In this way the parts of prudence, if we take them properly, are the prudence whereby a man rules himself, and the prudence whereby a man governs a multitude, which differ specifically as stated above (Question [47], Article [11]). Again, the prudence whereby a multitude is governed, is divided into various species according to the various kinds of multitude. There is the multitude which is united together for some particular purpose; thus an army is gathered together to fight, and the prudence that governs this is called "military." There is also the multitude that is united together for the whole of life; such is the multitude of a home or family, and this is ruled by "domestic prudence": and such again is the multitude of a city or kingdom, the ruling principle of which is "regnative prudence" in the ruler, and "political prudence," simply so called, in the subjects.If, however, prudence be taken in a wide sense, as including also speculative knowledge, as stated above (Question [47], Article [2], ad 2) then its parts include "dialectics," "rhetoric" and "physics," according to three methods of prudence in the sciences. The first of these is the attaining of science by demonstration, which belongs to "physics" (if physics be understood to comprise all demonstrative sciences). The second method is to arrive at an opinion through probable premises, and this belongs to "dialectics." The third method is to employ conjectures in order to induce a certain suspicion, or to persuade somewhat, and this belongs to "rhetoric." It may be said, however, that these three belong also to prudence properly so called, since it argues sometimes from necessary premises, sometimes from probabilities, and sometimes from conjectures.The potential parts of a virtue are the virtues connected with it, which are directed to certain secondary acts or matters, not having, as it were, the whole power of the principal virtue. In this way the parts of prudence are "good counsel," which concerns counsel, "synesis," which concerns judgment in matters of ordinary occurrence, and "gnome," which concerns judgment in matters of exception to the law: while "prudence" is about the chief act, viz. that of commanding.
Reply to Objection: 1. The various enumerations differ, either because different kinds of parts are assigned, or because that which is mentioned in one enumeration includes several mentioned in another enumeration. Thus Tully includes "caution" and "circumspection" under "foresight," and "reasoning," "docility" and "shrewdness" under "understanding."
2. Here domestic and civic prudence are not to be taken as sciences, but as kinds of prudence. As to the other three, the reply may be gathered from what has been said.
3. All these things are reckoned parts of prudence, not by taking them altogether, but in so far as they are connected with things pertaining to prudence.
4. Right command and right use always go together, because the reason's command is followed by obedience on the part of the lower powers, which pertain to use.
5. Solicitude is included under foresight.
We must now consider each quasi-integral part of prudence, and under this head there are eight points of inquiry:
(1) Memory;
(2) Understanding or Intelligence;
(3) Docility;
(4) Shrewdness;
(5) Reason;
(6) Foresight;
(7) Circumspection;
(8) Caution.
Whether memory is a part of prudence?
Objection: 1. It would seem that memory is not a part of prudence. For memory, as the Philosopher proves (De Memor. et Remin. i), is in the sensitive part of the soul: whereas prudence is in the rational part (Ethic. vi, 5). Therefore memory is not a part of prudence.
2. Further, prudence is acquired and perfected by experience, whereas memory is in us from nature. Therefore memory is not a part of prudence.
3. Further, memory regards the past, whereas prudence regards future matters of action, about which counsel is concerned, as stated in Ethic. vi, 2,7. Therefore memory is not a part of prudence.
On the contrary Tully (De Invent. Rhet. ii, 53) places memory among the parts of prudence.
I answer that Prudence regards contingent matters of action, as stated above (Question [47], Article [5]). Now in such like matters a man can be directed, not by those things that are simply and necessarily true, but by those which occur in the majority of cases: because principles must be proportionate to their conclusions, and "like must be concluded from like" (Ethic. vi [*Anal. Post. i. 32]). But we need experience to discover what is true in the majority of cases: wherefore the Philosopher says (Ethic. ii, 1) that "intellectual virtue is engendered and fostered by experience and time." Now experience is the result of many memories as stated in Metaph. i, 1, and therefore prudence requires the memory of many things. Hence memory is fittingly accounted a part of prudence.
Reply to Objection: 1. As stated above (Question [47], Articles [3],6), prudence applies universal knowledge to particulars which are objects of sense: hence many things belonging to the sensitive faculties are requisite for prudence, and memory is one of them.
2. Just as aptitude for prudence is in our nature, while its perfection comes through practice or grace, so too, as Tully says in his Rhetoric [*Ad Herenn. de Arte Rhet. iii, 16,24], memory not only arises from nature, but is also aided by art and diligence.There are four things whereby a man perfects his memory. First, when a man wishes to remember a thing, he should take some suitable yet somewhat unwonted illustration of it, since the unwonted strikes us more, and so makes a greater and stronger impression on the mind; the mind; and this explains why we remember better what we saw when we were children. Now the reason for the necessity of finding these illustrations or images, is that simple and spiritual impressions easily slip from the mind, unless they be tied as it were to some corporeal image, because human knowledge has a greater hold on sensible objects. For this reason memory is assigned to the sensitive part of the soul. Secondly, whatever a man wishes to retain in his memory he must carefully consider and set in order, so that he may pass easily from one memory to another. Hence the Philosopher says (De Memor. et Remin. ii): "Sometimes a place brings memories back to us: the reason being that we pass quickly from the one to the other." Thirdly, we must be anxious and earnest about the things we wish to remember, because the more a thing is impressed on the mind, the less it is liable to slip out of it. Wherefore Tully says in his Rhetoric [*Ad Herenn. de Arte Rhet. iii.] that "anxiety preserves the figures of images entire." Fourthly, we should often reflect on the things we wish to remember. Hence the Philosopher says (De Memoria i) that "reflection preserves memories," because as he remarks (De Memoria ii) "custom is a second nature": wherefore when we reflect on a thing frequently, we quickly call it to mind, through passing from one thing to another by a kind of natural order.
3. It behooves us to argue, as it were, about the future from the past; wherefore memory of the past is necessary in order to take good counsel for the future.
Objection: 1. It would seem that understanding is not a part of prudence. When two things are members of a division, one is not part of the other. But intellectual virtue is divided into understanding and prudence, according to Ethic. vi, 3. Therefore understanding should not be reckoned a part of prudence.
2. Further, understanding is numbered among the gifts of the Holy Ghost, and corresponds to faith, as stated above (Question [8], Articles [1],8). But prudence is a virtue other than faith, as is clear from what has been said above (Question [4], Article [8]; FS, Question [62], Article [2]). Therefore understanding does not pertain to prudence.
3. Further, prudence is about singular matters of action (Ethic. vi, 7): whereas understanding takes cognizance of universal and immaterial objects (De Anima iii, 4). Therefore understanding is not a part of prudence.
On the contrary Tully [*De Invent. Rhet. ii, 53] accounts "intelligence" a part of prudence, and Macrobius [*In Somn. Scip. i, 8] mentions "understanding," which comes to the same.
I answer that Understanding denotes here, not the intellectual power, but the right estimate about some final principle, which is taken as self-evident: thus we are said to understand the first principles of demonstrations. Now every deduction of reason proceeds from certain statements which are taken as primary: wherefore every process of reasoning must needs proceed from some understanding. Therefore since prudence is right reason applied to action, the whole process of prudence must needs have its source in understanding. Hence it is that understanding is reckoned a part of prudence.
Reply to Objection: 1. The reasoning of prudence terminates, as in a conclusion, in the particular matter of action, to which, as stated above (Question [47], Articles [3],6), it applies the knowledge of some universal principle. Now a singular conclusion is argued from a universal and a singular proposition. Wherefore the reasoning of prudence must proceed from a twofold understanding. The one is cognizant of universals, and this belongs to the understanding which is an intellectual virtue, whereby we know naturally not only speculative principles, but also practical universal principles, such as "One should do evil to no man," as shown above (Question [47], Article [6]). The other understanding, as stated in Ethic. vi, 11, is cognizant of an extreme, i.e. of some primary singular and contingent practical matter, viz. the minor premiss, which must needs be singular in the syllogism of prudence, as stated above (Question [47], Articles [3],6). Now this primary singular is some singular end, as stated in the same place. Wherefore the understanding which is a part of prudence is a right estimate of some particular end.
2. The understanding which is a gift of the Holy Ghost, is a quick insight into divine things, as shown above (Question [8], Articles [1],2). It is in another sense that it is accounted a part of prudence, as stated above.
3. The right estimate about a particular end is called both "understanding," in so far as its object is a principle, and "sense," in so far as its object is a particular. This is what the Philosopher means when he says (Ethic. v, 11): "Of such things we need to have the sense, and this is understanding." But this is to be understood as referring, not to the particular sense whereby we know proper sensibles, but to the interior sense, whereby we judge of a particular.
Objection: 1. It would seem that docility should not be accounted a part of prudence. For that which is a necessary condition of every intellectual virtue, should not be appropriated to one of them. But docility is requisite for every intellectual virtue. Therefore it should not be accounted a part of prudence.
2. Further, that which pertains to a human virtue is in our power, since it is for things that are in our power that we are praised or blamed. Now it is not in our power to be docile, for this is befitting to some through their natural disposition. Therefore it is not a part of prudence.
3. Further, docility is in the disciple: whereas prudence, since it makes precepts, seems rather to belong to teachers, who are also called "preceptors." Therefore docility is not a part of prudence.
On the contrary Macrobius [*In Somn. Scip. i, 8] following the opinion of Plotinus places docility among the parts of prudence.
I answer that As stated above (Article [2], ad 1; Question [47], Article [3]) prudence is concerned with particular matters of action, and since such matters are of infinite variety, no one man can consider them all sufficiently; nor can this be done quickly, for it requires length of time. Hence in matters of prudence man stands in very great need of being taught by others, especially by old folk who have acquired a sane understanding of the ends in practical matters. Wherefore the Philosopher says (Ethic. vi, 11): "It is right to pay no less attention to the undemonstrated assertions and opinions of such persons as are experienced, older than we are, and prudent, than to their demonstrations, for their experience gives them an insight into principles." Thus it is written (Pr 3,5): "Lean not on thy own prudence," and (Si 6,35): "Stand in the multitude of the ancients" (i.e. the old men), "that are wise, and join thyself from thy heart to their wisdom." Now it is a mark of docility to be ready to be taught: and consequently docility is fittingly reckoned a part of prudence
Reply to Objection: 1. Although docility is useful for every intellectual virtue, yet it belongs to prudence chiefly, for the reason given above.
2. Man has a natural aptitude for docility even as for other things connected with prudence. Yet his own efforts count for much towards the attainment of perfect docility: and he must carefully, frequently and reverently apply his mind to the teachings of the learned, neither neglecting them through laziness, nor despising them through pride.
3. By prudence man makes precepts not only for others, but also for himself, as stated above (Question [47], Article [12], ad 3). Hence as stated (Ethic. vi, 11), even in subjects, there is place for prudence; to which docility pertains. And yet even the learned should be docile in some respects, since no man is altogether self-sufficient in matters of prudence, as stated above.
Objection: 1. It would seem that shrewdness is not a part of prudence. For shrewdness consists in easily finding the middle term for demonstrations, as stated in Poster. i, 34. Now the reasoning of prudence is not a demonstration since it deals with contingencies. Therefore shrewdness does not pertain to prudence.
2. Further, good counsel pertains to prudence according to Ethic. vi, 5,7,9. Now there is no place in good counsel for shrewdness [*Ethic. vi, 9; Poster. i, 34] which is a kind of (eustochia), i.e. "a happy conjecture": for the latter is "unreasoning and rapid," whereas counsel needs to be slow, as stated in Ethic. vi, 9. Therefore shrewdness should not be accounted a part of prudence.
3. Further, shrewdness as stated above (Question [48]) is a "happy conjecture." Now it belongs to rhetoricians to make use of conjectures. Therefore shrewdness belongs to rhetoric rather than to prudence.
On the contrary Isidore says (Etym. x): "A solicitous man is one who is shrewd and alert [solers citus]." But solicitude belongs to prudence, as stated above (Question [47], Article [9]). Therefore shrewdness does also.
I answer that Prudence consists in a right estimate about matters of action. Now a right estimate or opinion is acquired in two ways, both in practical and in speculative matters, first by discovering it oneself, secondly by learning it from others. Now just as docility consists in a man being well disposed to acquire a right opinion from another man, so shrewdness is an apt disposition to acquire a right estimate by oneself, yet so that shrewdness be taken for (eustochia), of which it is a part. For (eustochia) is a happy conjecture about any matter, while shrewdness is "an easy and rapid conjecture in finding the middle term" (Poster. i, 34). Nevertheless the philosopher [*Andronicus; Cf. Question [48], Objection [1]] who calls shrewdness a part of prudence, takes it for (eustochia), in general, hence he says: "Shrewdness is a habit whereby congruities are discovered rapidly."
Reply to Objection: 1. Shrewdness is concerned with the discovery of the middle term not only in demonstrative, but also in practical syllogisms, as, for instance, when two men are seen to be friends they are reckoned to be enemies of a third one, as the Philosopher says (Poster. i, 34). In this way shrewdness belongs to prudence.
2. The Philosopher adduces the true reason (Ethic. vi, 9) to prove that (euboulia), i.e. good counsel, is not (eustochia), which is commended for grasping quickly what should be done. Now a man may take good counsel, though he be long and slow in so doing, and yet this does not discount the utility of a happy conjecture in taking good counsel: indeed it is sometimes a necessity, when, for instance, something has to be done without warning. It is for this reason that shrewdness is fittingly reckoned a part of prudence.
3. Rhetoric also reasons about practical matters, wherefore nothing hinders the same thing belonging both to rhetoric and prudence. Nevertheless, conjecture is taken here not only in the sense in which it is employed by rhetoricians, but also as applicable to all matters whatsoever wherein man is said to conjecture the truth.
Objection: 1. It would seem that reason should not be reckoned a part of prudence. For the subject of an accident is not a part thereof. But prudence is in the reason as its subject (Ethic. vi, 5). Therefore reason should not be reckoned a part of prudence.
2. Further, that which is common to many, should not be reckoned a part of any one of them; or if it be so reckoned, it should be reckoned a part of that one to which it chiefly belongs. Now reason is necessary in all the intellectual virtues, and chiefly in wisdom and science, which employ a demonstrative reason. Therefore reason should not be reckoned a part of prudence
3. Further, reason as a power does not differ essentially from the intelligence, as stated above (FP, Question [79], Article [8]). If therefore intelligence be reckoned a part of prudence, it is superfluous to add reason.
On the contrary Macrobius [*In Somn. Scip. i], following the opinion of Plotinus, numbers reason among the parts of prudence.
I answer that The work of prudence is to take good counsel, as stated in Ethic. vi, 7. Now counsel is a research proceeding from certain things to others. But this is the work of reason. Wherefore it is requisite for prudence that man should be an apt reasoner. And since the things required for the perfection of prudence are called requisite or quasi-integral parts of prudence, it follows that reason should be numbered among these parts.
Reply to Objection: 1. Reason denotes here, not the power of reason, but its good use.
2. The certitude of reason comes from the intellect. Yet the need of reason is from a defect in the intellect, since those things in which the intellective power is in full vigor, have no need for reason, for they comprehend the truth by their simple insight, as do God and the angels. On the other hand particular matters of action, wherein prudence guides, are very far from the condition of things intelligible, and so much the farther, as they are less certain and fixed. Thus matters of art, though they are singular, are nevertheless more fixed and certain, wherefore in many of them there is no room for counsel on account of their certitude, as stated in Ethic. iii, 3. Hence, although in certain other intellectual virtues reason is more certain than in prudence, yet prudence above all requires that man be an apt reasoner, so that he may rightly apply universals to particulars, which latter are various and uncertain.
3. Although intelligence and reason are not different powers, yet they are named after different acts. For intelligence takes its name from being an intimate penetration of the truth [*Cf. SS, Question [8], Article [1]], while reason is so called from being inquisitive and discursive. Hence each is accounted a part of reason as explained above (Article [2]; Question [47], Article [2],3).
Summa Th. II-II EN Qu.47 a.14