Question Four: On the Distinction of Habits

St. Thomas, I-II, q. 54 and 56, a. 2.

573. There are several rules according to which habits are distinguished in species (a. 2):

1. As forms are distinguished by reason of cause: habits whose proper and per se causes are diverse are distinguished in species, for every agent acts so as to produce something similar to itself according to species. Thus habits are distinguished which are acquired by diverse acts; likewise acquired habits, which we acquire by our acts, and infused habits per se, which God alone can give us.

2. As habits are distinguished by reason of nature: habits which state a diverse order to nature (and consequently to the end) are distinguished in species, as good and bad habits; or habits which state an order to a diverse nature, as ordinary human virtue and divine or heroic virtue, which is suitable to a superior nature.

3. As operative habits are distinguished by reason of the object: habits which have diverse formal objects are distinguished in species; for habits are dispositions to acts; therefore if acts are distinguished in species according to objects, habits also are. - This is the chief rule, because it indicates the ultimate species.

The three aforesaid rules are fundamental; but from the last there follows a derived rule, namely:

4. That habits consequently are distinguished by reason of the subject: habits which inhere in diverse powers operating principally are distinguished in species. For the powers themselves are distinguished from objects generically distinct. Whence where the powers are diverse, the objects also are diverse.¹

¹ Hence the distinctive principle is the object, because powers are distinguished from the object. The disposition of the subject is not the principle of distinction by reason of itself but by reason of the object. Whence here, in truth, a new rule distinct from the third is not handed down.

574. Corollaries. - 1. From the third rule it follows that habits of diverse species can inhere in one and the same power, because a power can be ordered to diverse objects.

2. The fourth rule of specific distinction by reason of the subject or power is to be understood of powers which operate principally. For those which operate secondarily, by serving the principal act or by disposing to it, tend toward the object of the principal operation, and therefore the secondary habits which inhere in them have their species from this object: thus the operation of art in the hand takes its species from the object of the art which is in the intellect.

3. Hence one habit or one virtue cannot be equally and according to essence in several powers; nevertheless it can pertain to several powers in a certain order, so that it is in one principally and secondarily extends itself to others: either by way of diffusion, according as one power moves another which serves it, for example, justice commands frugality or temperance; or by way of disposition, according as one receives from another, for example, prudence rectifying the choice of means supposes rectitude of the appetite concerning the end (q. 66, a. 2).