Man has freedom of choice. For some things act without judgment, as a stone falls; others with judgment but without freedom, as the lower animals, which judge by instinct, not by collating; while man acts by judgment, with the power of choosing diversely by seeking out reasons. By this means, as regards contingent objects, the understanding finds a way to reach an opposite conclusion, and since particular works are contingent, man stands towards them free and undetermined.
This free will is a faculty, not a habit: for if it were a habit it would have to be a natural one, since man possesses free will by nature; the things to which we are inclined by nature, however, are not the objects of free will; hence it is contrary to reason to ascribe free will to a natural habit. Secondly, habits are the result of our passions, or of our good or bad acts; but free will stands indifferently to the choice of good or evil; hence it is not a habit; we conclude, therefore, that it is a faculty.
It is, moreover, an appetitive faculty, since election is its virtual act; for we can refuse one thing and choose the other, which is election, in which something is due to the understanding, i. e. counsel, while acceptance belongs to the concurrence of the will. But because things which conduce to the end are conceived as good in virtue of being useful, Aristotle inclines to the opinion that election belongs chiefly to the will.
And this freedom of choice is one faculty with the will, not another; for as intellect, which is simple intelligence, stands to reason which is discursive, so the will which is the end stands to that freedom of choice which is the way to the end. Thus they are diverse acts of the same faculty.
- text taken from Compendium of the Summa Theologica of Saint Thomas Aquinas, by Bishop Berardus Bongiovanni