Objection 1. It would seem that the habits of the speculative intellect are not virtues. For virtue is an operative habit, as we have said above (Question 55, Article 2). But speculative habits are not operative: for speculative matter is distinct from practical, i.e. operative matter. Therefore the habits of the speculative intellect are not virtues.
Objection 2. Further, virtue is about those things by which man is made happy or blessed: for "happiness is the reward of virtue" (Ethic. i, 9). Now intellectual habits do not consider human acts or other human goods, by which man acquires happiness, but rather things pertaining to nature or to God. Therefore such like habits cannot be called virtues.
Objection 3. Further, science is a speculative habit. But science and virtue are distinct from one another as genera which are not subalternate, as the Philosopher proves in Topic. iv. Therefore speculative habits are not virtues.
On the contrary, The speculative habits alone consider necessary things which cannot be otherwise than they are. Now the Philosopher (Ethic. vi, 1) places certain intellectual virtues in that part of the soul which considers necessary things that cannot be otherwise than they are. Therefore the habits of the speculative intellect are virtues.
I answer that, Since every virtue is ordained to some good, as stated above (Question 55, Article 3), a habit, as we have already observed (56, 3), may be called a virtue for two reasons: first, because it confers aptness in doing good; secondly, because besides aptness, it confers the right use of it. The latter condition, as above stated (55, 3), belongs to those habits alone which affect the appetitive part of the soul: since it is the soul's appetitive power that puts all the powers and habits to their respective uses.
Since, then, the habits of the speculative intellect do not perfect the appetitive part, nor affect it in any way, but only the intellective part; they may indeed be called virtues in so far as they confer aptness for a good work, viz. the consideration of truth (since this is the good work of the intellect): yet they are not called virtues in the second way, as though they conferred the right use of a power or habit. For if a man possess a habit of speculative science, it does not follow that he is inclined to make use of it, but he is made able to consider the truth in those matters of which he has scientific knowledge: that he make use of the knowledge which he has, is due to the motion of his will. Consequently a virtue which perfects the will, as charity or justice, confers the right use of these speculative habits. And in this way too there can be merit in the acts of these habits, if they be done out of charity: thus Gregory says (Moral. vi) that the "contemplative life has greater merit than the active life."
Reply to Objection 1. Work is of two kinds, exterior and interior. Accordingly the practical or active faculty which is contrasted with the speculative faculty, is concerned with exterior work, to which the speculative habit is not ordained. Yet it is ordained to the interior act of the intellect which is to consider the truth. And in this way it is an operative habit.
Reply to Objection 2. Virtue is about certain things in two ways. In the first place a virtue is about its object. And thus these speculative virtues are not about those things whereby man is made happy; except perhaps, in so far as the word "whereby" indicates the efficient cause or object of complete happiness, i.e. God, Who is the supreme object of contemplation. Secondly, a virtue is said to be about its acts: and in this sense the intellectual virtues are about those things whereby a man is made happy; both because the acts of these virtues can be meritorious, as stated above, and because they are a kind of beginning of perfect bliss, which consists in the contemplation of truth, as we have already stated (3, 7).
Reply to Objection 3. Science is contrasted with virtue taken in the second sense, wherein it belongs to the appetitive faculty.
Source: Summa Theologica (New Advent)