Whether habits are distinguished by their objects?
Objection 1: It would seem that habits are not distinguished by their objects. For contraries differ in species. Now the same habit of science regards contraries: thus medicine regards the healthy and the unhealthy. Therefore habits are not distinguished by objects specifically distinct.
Objection 2: Further, different sciences are different habits. But the same scientific truth belongs to different sciences: thus both the physicist and the astronomer prove the earth to be round, as stated in Phys. ii, text. 17. Therefore habits are not distinguished by their objects.
Objection 3: Further, wherever the act is the same, the object is the same. But the same act can belong to different habits of virtue, if it be directed to different ends; thus to give money to anyone, if it be done for God's sake, is an act of charity; while, if it be done in order to pay a debt, it is an act of justice. Therefore the same object can also belong to different habits. Therefore diversity of habits does not follow diversity of objects.
On the contrary, Acts differ in species according to the diversity of their objects, as stated above (Q 18, A 5). But habits are dispositions to acts. Therefore habits also are distinguished according to the diversity of objects.
I answer that, A habit is both a form and a habit. Hence the specific distinction of habits may be taken in the ordinary way in which forms differ specifically; or according to that mode of distinction which is proper to habits. Accordingly forms are distinguished from one another in reference to the diversity of their active principles, since every agent produces its like in species. Habits, however, imply order to something: and all things that imply order to something, are distinguished according to the distinction of the things to which they are ordained. Now a habit is a disposition implying a twofold order: viz. to nature and to an operation consequent to nature.
Accordingly habits are specifically distinct in respect of three things. First, in respect of the active principles of such dispositions; secondly, in respect of nature; thirdly, in respect of specifically different objects, as will appear from what follows.
Reply to Objection 1: In distinguishing powers, or also habits, we must consider the object not in its material but in its formal aspect, which may differ in species or even in genus. And though the distinction between specific contraries is a real distinction yet they are both known under one aspect, since one is known through the other. And consequently in so far as they concur in the one aspect of cognoscibility, they belong to one cognitive habit.
Reply to Objection 2: The physicist proves the earth to be round by one means, the astronomer by another: for the latter proves this by means of mathematics, e.g. by the shapes of eclipses, or something of the sort; while the former proves it by means of physics, e.g. by the movement of heavy bodies towards the center, and so forth. Now the whole force of a demonstration, which is "a syllogism producing science," as stated in Poster. i, text. 5, depends on the mean. And consequently various means are as so many active principles, in respect of which the habits of science are distinguished.
Reply to Objection 3: As the Philosopher says (Phys. ii, text. 89; Ethic. vii, 8), the end is, in practical matters, what the principle is in speculative matters. Consequently diversity of ends demands a diversity of virtues, even as diversity of active principles does. Moreover the ends are objects of the internal acts, with which, above all, the virtues are concerned, as is evident from what has been said (Q 18, A 6; Q 19, A 2, ad 1; Q 34, A 4).
I–II · Q. 54, Art. 3: Whether habits are divided into good and bad?
Whether habits are divided into good and bad?
Objection 1: It would seem that habits are not divided into good and bad. For good and bad are contraries. Now the same habit regards contraries, as was stated above (A 2, OBJ). Therefore habits are not divided into good and bad.
Objection 2: Further, good is convertible with being; so that, since it is common to all, it cannot be accounted a specific difference, as the Philosopher declares (Topic. iv). Again, evil, since it is a privation and a non-being, cannot differentiate any being. Therefore habits cannot be specifically divided into good and evil.
Objection 3: Further, there can be different evil habits about one same object; for instance, intemperance and insensibility about matters of concupiscence: and in like manner there can be several good habits; for instance, human virtue and heroic or godlike virtue, as the Philosopher clearly states (Ethic. vii, 1). Therefore, habits are not divided into good and bad.
On the contrary, A good habit is contrary to a bad habit, as virtue to vice. Now contraries are divided specifically into good and bad habits.
I answer that, As stated above (A 2), habits are specifically distinct not only in respect of their objects and active principles, but also in their relation to nature. Now, this happens in two ways. First, by reason of their suitableness or unsuitableness to nature. In this way a good habit is specifically distinct from a bad habit: since a good habit is one which disposes to an act suitable to the agent's nature, while an evil habit is one which disposes to an act unsuitable to nature. Thus, acts of virtue are suitable to human nature, since they are according to reason, whereas acts of vice are discordant from human nature, since they are against reason. Hence it is clear that habits are distinguished specifically by the difference of good and bad.
Secondly, habits are distinguished in relation to nature, from the fact that one habit disposes to an act that is suitable to a lower nature, while another habit disposes to an act befitting a higher nature. And thus human virtue, which disposes to an act befitting human nature, is distinct from godlike or heroic virtue, which disposes to an act befitting some higher nature.
Reply to Objection 1: The same habit may be about contraries in so far as contraries agree in one common aspect. Never, however, does it happen that contrary habits are in one species: since contrariety of habits follows contrariety of aspect. Accordingly habits are divided into good and bad, namely, inasmuch as one habit is good, and another bad; but not by reason of one habit being something good, and another about something bad.
Reply to Objection 2: It is not the good which is common to every being, that is a difference constituting the species of a habit; but some determinate good by reason of suitability to some determinate, viz. the human, nature. In like manner the evil that constitutes a difference of habits is not a pure privation, but something determinate repugnant to a determinate nature.
Reply to Objection 3: Several good habits about one same specific thing are distinct in reference to their suitability to various natures, as stated above. But several bad habits in respect of one action are distinct in reference to their diverse repugnance to that which is in keeping with nature: thus, various vices about one same matter are contrary to one virtue.