Objection 1. It would seem that euboulia (deliberating well) is not a virtue. For, according to Augustine (De Lib. Arb. ii, 18,19) "no man makes evil use of virtue." Now some make evil use of euboulia (deliberating well) or good counsel, either through devising crafty counsels in order to achieve evil ends, or through committing sin in order that they may achieve good ends, as those who rob that they may give alms. Therefore euboulia (deliberating well) is not a virtue.
Objection 2. Further, virtue is a perfection, according to Phys. vii. But euboulia (deliberating well) is concerned with counsel, which implies doubt and research, and these are marks of imperfection. Therefore euboulia (deliberating well) is not a virtue.
Objection 3. Further, virtues are connected with one another, as stated above (I-II, 65). Now euboulia (deliberating well) is not connected with the other virtues, since many sinners take good-counsel, and many godly men are slow in taking counsel. Therefore euboulia (deliberating well) is not a virtue.
On the contrary, According to the Philosopher (Ethic. vi, 9) euboulia (deliberating well) "is a right counselling." Now the perfection of virtue consists in right reason. Therefore euboulia (deliberating well) is a virtue.
I answer that, As stated above (Question 47, Article 4) the nature of a human virtue consists in making a human act good. Now among the acts of man, it is proper to him to take counsel, since this denotes a research of the reason about the actions he has to perform and whereof human life consists, for the speculative life is above man, as stated in Ethic. x.
But euboulia (deliberating well) signifies goodness of counsel, for it is derived from the eu, good, and boule, counsel, being "a good counsel" or rather "a disposition to take good counsel." Hence it is evident that euboulia (deliberating well) is a human virtue.
Reply to Objection 1. There is no good counsel either in deliberating for an evil end, or in discovering evil means for attaining a good end, even as in speculative matters, there is no good reasoning either in coming to a false conclusion, or in coming to a true conclusion from false premisses through employing an unsuitable middle term. Hence both the aforesaid processes are contrary to euboulia (deliberating well), as the Philosopher declares (Ethic. vi, 9).
Reply to Objection 2. Although virtue is essentially a perfection, it does not follow that whatever is the matter of a virtue implies perfection. For man needs to be perfected by virtues in all his parts, and this not only as regards the acts of reason, of which counsel is one, but also as regards the passions of the sensitive appetite, which are still more imperfect.
It may also be replied that human virtue is a perfection according to the mode of man, who is unable by simple insight to comprehend with certainty the truth of things, especially in matters of action which are contingent.
Reply to Objection 3. In no sinner as such is euboulia (deliberating well) to be found: since all sin is contrary to taking good counsel. For good counsel requires not only the discovery or devising of fit means for the end, but also other circumstances. Such are suitable time, so that one be neither too slow nor too quick in taking counsel, and the mode of taking counsel, so that one be firm in the counsel taken, and other like due circumstances, which sinners fail to observe when they sin. On the other hand, every virtuous man takes good counsel in those things which are directed to the end of virtue, although perhaps he does not take good counsel in other particular matters, for instance in matters of trade, or warfare, or the like.
Source: Summa Theologica (New Advent)