A2 Whether there are four cardinal virtues?

[a] Objection 1:
It would seem that there are not four cardinal virtues. For prudence is the directing principle of the other moral virtues, as is clear from what has been said above ([1568] Q [58], A [4]). But that which directs other things ranks before them. Therefore prudence alone is a principal virtue.

[b] Objection 2:
Further, the principal virtues are, in a way, moral virtues. Now we are directed to moral works both by the practical reason, and by a right appetite, as stated in Ethic. vi, 2. Therefore there are only two cardinal virtues.

[c] Objection 3:
Further, even among the other virtues one ranks higher than another. But in order that a virtue be principal, it needs not to rank above all the others, but above some. Therefore it seems that there are many more principal virtues.

[d] On the contrary,
Gregory says (Moral. ii): "The entire structure of good works is built on four virtues."

[e] I answer that,
Things may be numbered either in respect of their formal principles, or according to the subjects in which they are: and either way we find that there are four cardinal virtues.

[f] For the formal principle of the virtue of which we speak now is good as defined by reason; which good is considered in two ways. First, as existing in the very act of reason: and thus we have one principal virtue, called "Prudence." Secondly, according as the reason puts its order into something else; either into operations, and then we have "Justice"; or into passions, and then we need two virtues. For the need of putting the order of reason into the passions is due to their thwarting reason: and this occurs in two ways. First, by the passions inciting to something against reason, and then the passions need a curb, which we call "Temperance." Secondly, by the passions withdrawing us from following the dictate of reason, e. g. through fear of danger or toil: and then man needs to be strengthened for that which reason dictates, lest he turn back; and to this end there is "Fortitude."

[g] In like manner, we find the same number if we consider the subjects of virtue. For there are four subjects of the virtue we speak of now: viz. the power which is rational in its essence, and this is perfected by "Prudence"; and that which is rational by participation, and is threefold, the will, subject of "Justice," the concupiscible faculty, subject of "Temperance," and the irascible faculty, subject of "Fortitude."

[h] Reply to Objection 1:
Prudence is the principal of all the virtues simply. The others are principal, each in its own genus.

[i] Reply to Objection 2:
That part of the soul which is rational by participation is threefold, as stated above.

[j] Reply to Objection 3:
All the other virtues among which one ranks before another, are reducible to the above four, both as to the subject and as to the formal principle.