Reply Obj. 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. _______________________
THIRD ARTICLE [II-II, Q. 47, Art. 3]
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.
Obj. 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.
Obj. 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 Obj. 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 Obj. 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.