Objection 1. It seems that shamefacedness is a virtue. For it is proper to a virtue "to observe the mean as fixed by reason": this is clear from the definition of virtue given in Ethic. ii, 6. Now shamefacedness observes the mean in this way, as the Philosopher observes (Ethic. ii, 7). Therefore shamefacedness is a virtue.
Objection 2. Further, whatever is praiseworthy is either a virtue or something connected with virtue. Now shamefacedness is praiseworthy. But it is not part of a virtue. For it is not a part of prudence, since it is not in the reason but in the appetite; nor is it a part of justice. since shamefacedness implies a certain passion, whereas justice is not about the passions; nor again is it a part of fortitude, because it belongs to fortitude to be persistent and aggressive, while it belongs to shamefacedness to recoil from something; nor lastly is it a part of temperance, since the latter is about desires, whereas shamefacedness is a kind of fear according as the Philosopher states (Ethic. iv, 9) and Damascene (De Fide Orth. ii, 15). Hence it follows that shamefacedness is a virtue.
Objection 3. Further, the honest and the virtuous are convertible according to Tully (De Offic. i, 27). Now shamefacedness is a part of honesty: for Ambrose says (De Offic. i, 43) that "shamefacedness is the companion and familiar of the restful mind, averse to wantonness, a stranger to any kind of excess, the friend of sobriety and the support of what is honest, a seeker after the beautiful." Therefore shamefacedness is a virtue.
Objection 4. Further, every vice is opposed to a virtue. Now certain vices are opposed to shamefacedness, namely shamelessness and inordinate prudery. Therefore shamefacedness is a virtue.
Objection 5. Further, "like acts beget like habits," according to Ethic. ii, 1. Now shamefacedness implies a praiseworthy act; wherefore from many such acts a habit results. But a habit of praiseworthy deeds is a virtue, according to the Philosopher (Ethic. i, 12). Therefore shamefacedness is a virtue.
On the contrary, The Philosopher says (Ethic. ii, 7; iv, 9) that shamefacedness is not a virtue.
I answer that, Virtue is taken in two ways, in a strict sense and in a broad sense. Taken strictly virtue is a perfection, as stated in Phys. vii, 17,18. Wherefore anything that is inconsistent with perfection, though it be good, falls short of the notion of virtue. Now shamefacedness is inconsistent with perfection, because it is the fear of something base, namely of that which is disgraceful. Hence Damascene says (De Fide Orth. ii, 15) that "shamefacedness is fear of a base action." Now just as hope is about a possible and difficult good, so is fear about a possible and arduous evil, as stated above (I-II, 40, 1; I-II, 41, 2; I-II, 42, 3), when we were treating of the passions. But one who is perfect as to a virtuous habit, does not apprehend that which would be disgraceful and base to do, as being possible and arduous, that is to say difficult for him to avoid; nor does he actually do anything base, so as to be in fear of disgrace. Therefore shamefacedness, properly speaking, is not a virtue, since it falls short of the perfection of virtue.
Taken, however, in a broad sense virtue denotes whatever is good and praiseworthy in human acts or passions; and in this way shamefacedness is sometimes called a virtue, since it is a praiseworthy passion.
Reply to Objection 1. Observing the mean is not sufficient for the notion of virtue, although it is one of the conditions included in virtue's definition: but it is requisite, in addition to this, that it be "an elective habit," that is to say, operating from choice. Now shamefacedness denotes, not a habit but a passion, nor does its movement result from choice, but from an impulse of passion. Hence it falls short of the notion of virtue.
Reply to Objection 2. As stated above, shamefacedness is fear of baseness and disgrace. Now it has been stated (142, 4) that the vice of intemperance is most base and disgraceful. Wherefore shamefacedness pertains more to temperance than to any other virtue, by reason of its motive cause, which is a base action though not according to the species of the passion, namely fear. Nevertheless in so far as the vices opposed to other virtues are base and disgraceful, shamefacedness may also pertain to other virtues.
Reply to Objection 3. Shamefacedness fosters honesty, by removing that which is contrary thereto, but not so as to attain to the perfection of honesty.
Reply to Objection 4. Every defect causes a vice, but not every good is sufficient for the notion of virtue. Consequently it does not follow that whatever is directly opposed to vice is a virtue, although every vice is opposed to a virtue, as regards its origin. Hence shamelessness, in so far as it results from excessive love of disgraceful things, is opposed to temperance.
Reply to Objection 5. Being frequently ashamed causes the habit of an acquired virtue whereby one avoids disgraceful things which are the object of shamefacedness, without continuing to be ashamed in their regard: although as a consequence of this acquired virtue, a man would be more ashamed, if confronted with the matter of shamefacedness.
Source: Summa Theologica (New Advent)