Objection 1. It would seem that prudence does not extend to the governing of many, but only to the government of oneself. For the Philosopher says (Ethic. v, 1) that virtue directed to the common good is justice. But prudence differs from justice. Therefore prudence is not directed to the common good.
Objection 2. Further, he seems to be prudent, who seeks and does good for himself. Now those who seek the common good often neglect their own. Therefore they are not prudent.
Objection 3. Further, prudence is specifically distinct from temperance and fortitude. But temperance and fortitude seem to be related only to a man's own good. Therefore the same applies to prudence.
On the contrary, Our Lord said (Matthew 24:45): "Who, thinkest thou, is a faithful and prudent [Douay: 'wise'] servant whom his lord hath appointed over his family?"
I answer that, According to the Philosopher (Ethic. vi, 8) some have held that prudence does not extend to the common good, but only to the good of the individual, and this because they thought that man is not bound to seek other than his own good. But this opinion is opposed to charity, which "seeketh not her own" (1 Corinthians 13:5): wherefore the Apostle says of himself (1 Corinthians 10:33): "Not seeking that which is profitable to myself, but to many, that they may be saved." Moreover it is contrary to right reason, which judges the common good to be better than the good of the individual.
Accordingly, since it belongs to prudence rightly to counsel, judge, and command concerning the means of obtaining a due end, it is evident that prudence regards not only the private good of the individual, but also the common good of the multitude.
Reply to Objection 1. The Philosopher is speaking there of moral virtue. Now just as every moral virtue that is directed to the common good is called "legal" justice, so the prudence that is directed to the common good is called "political" prudence, for the latter stands in the same relation to legal justice, as prudence simply so called to moral virtue.
Reply to Objection 2. He that seeks the good of the many, seeks in consequence his own good, for two reasons. First, because the individual good is impossible without the common good of the family, state, or kingdom. Hence Valerius Maximus says [Fact. et Dict. Memor. iv, 6 of the ancient Romans that "they would rather be poor in a rich empire than rich in a poor empire." Secondly, because, since man is a part of the home and state, he must needs consider what is good for him by being prudent about the good of the many. For the good disposition of parts depends on their relation to the whole; thus Augustine says (Confess. iii, 8) that "any part which does not harmonize with its whole, is offensive."
Reply to Objection 3. Even temperance and fortitude can be directed to the common good, hence there are precepts of law concerning them as stated in Ethic. v, 1: more so, however, prudence and justice, since these belong to the rational faculty which directly regards the universal, just as the sensitive part regards singulars.
Source: Summa Theologica (New Advent)