Objection 1. It seems that prudence about one's own good is the same specifically as that which extends to the common good. For the Philosopher says (Ethic. vi, 8) that "political prudence, and prudence are the same habit, yet their essence is not the same."
Objection 2. Further, the Philosopher says (Polit. iii, 2) that "virtue is the same in a good man and in a good ruler." Now political prudence is chiefly in the ruler, in whom it is architectonic, as it were. Since then prudence is a virtue of a good man, it seems that prudence and political prudence are the same habit.
Objection 3. Further, a habit is not diversified in species or essence by things which are subordinate to one another. But the particular good, which belongs to prudence simply so called, is subordinate to the common good, which belongs to political prudence. Therefore prudence and political prudence differ neither specifically nor essentially.
On the contrary, "Political prudence," which is directed to the common good of the state, "domestic economy" which is of such things as relate to the common good of the household or family, and "monastic economy" which is concerned with things affecting the good of one person, are all distinct sciences. Therefore in like manner there are different kinds of prudence, corresponding to the above differences of matter.
I answer that, As stated above (5; 54, 2, ad 1), the species of habits differ according to the difference of object considered in its formal aspect. Now the formal aspect of all things directed to the end, is taken from the end itself, as shown above (I-II, Prolog.; I-II, 102, 1), wherefore the species of habits differ by their relation to different ends. Again the individual good, the good of the family, and the good of the city and kingdom are different ends. Wherefore there must needs be different species of prudence corresponding to these different ends, so that one is "prudence" simply so called, which is directed to one's own good; another, "domestic prudence" which is directed to the common good of the home; and a third, "political prudence," which is directed to the common good of the state or kingdom.
Reply to Objection 1. The Philosopher means, not that political prudence is substantially the same habit as any kind of prudence, but that it is the same as the prudence which is directed to the common good. This is called "prudence" in respect of the common notion of prudence, i.e. as being right reason applied to action, while it is called "political," as being directed to the common good.
Reply to Objection 2. As the Philosopher declares (Polit. iii, 2), "it belongs to a good man to be able to rule well and to obey well," wherefore the virtue of a good man includes also that of a good ruler. Yet the virtue of the ruler and of the subject differs specifically, even as the virtue of a man and of a woman, as stated by the same authority (Polit. iii, 2).
Reply to Objection 3. Even different ends, one of which is subordinate to the other, diversify the species of a habit, thus for instance, habits directed to riding, soldiering, and civic life, differ specifically although their ends are subordinate to one another. On like manner, though the good of the individual is subordinate to the good of the many, that does not prevent this difference from making the habits differ specifically; but it follows that the habit which is directed to the last end is above the other habits and commands them.
Source: Summa Theologica (New Advent)