Whether there are four cardinal virtues?

Objections

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 (Question [58], Article [4]). But that which directs other things ranks before them. Therefore prudence alone is a principal virtue.
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.
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.