Article II: On Habit and Custom

St. Thomas, I, q. 83, a. 1, ad 5; I-II, q. 78, a. 2 and 4.

95. A habit is a firm and permanent disposition acquired from the repeated performance of acts, by which someone easily and promptly breaks forth into similar acts, and it can be defined: a facility and promptness, acquired by repeated acts, for placing similar acts. Custom is the very repetition of acts or the accustomed mode of acting; hence it is properly distinguished from an acquired habit and stands to it as cause to effect, indeed also as effect to cause: for custom is the cause of acquiring and strengthening a habit; but once the habit has already been acquired, it is itself the cause why the custom is continued. In the present question, however, moralists rather often use one for the other indiscriminately.

Custom can be contracted inadvertently and therefore without deliberation and involuntarily; or knowingly and freely contracted, and therefore voluntarily and deliberately. Moreover, once the habit has already been contracted, after its subject becomes conscious of it, either he retracts it efficaciously, that is, with a firm purpose of applying remedies suitable for uprooting it, in which case the habit is actually involuntary, although perhaps antecedently acquired voluntarily and freely; or he freely accepts and conserves it, or does not retract it but neglects to uproot it, in which case it is actually voluntary and free, although perhaps antecedently involuntary or not deliberate.

96. Principles. I. A custom that is not deliberate and is involuntary influences in the same way as antecedent concupiscence; hence it increases the voluntary as to propensity, but diminishes it as to freedom.

It should be noted: 1) if someone places an act solely from such custom and therefore altogether inadvertently, this will be non-voluntary and in no way deliberate, and consequently neither good nor evil; 2) deliberate custom, or custom freely admitted, if it is efficaciously retracted, that is, not by displeasure alone but by a firm purpose of acting to extirpate it, becomes actually involuntary; whence acts following from it alone are involuntary and not imputable, just as the cause itself or custom is; 3) if the habitual person afterward neglects in due time to employ efficacious remedies, the custom (from that negligence) again becomes indirectly voluntary and free, and consequently the acts following from it will be voluntary and free and imputable.

II. Deliberate and voluntary custom 1) always increases the voluntary as to propensity; 2) if, which is rarer, it removes all actual advertence and deliberation in the following acts, it diminishes freedom and consequently goodness or sin, because it removes the voluntary and free in itself and leaves only the voluntary and free in the cause, if the custom was deliberately acquired, or the indirect voluntary and free, if it was acquired without deliberation but is freely neglected so that it is not removed; 3) if, however, which is more frequent, it leaves sufficient advertence here and now, it does not remove freedom in itself but diminishes it somewhat, because ordinarily it clouds the intellect and its actual deliberation, and diminishes indifference; yet this diminution of liberty is perfectly compensated in the cause, because man freely contracted the habit and conserves it, and thus freely wills the very diminution of deliberation and liberty, which shows a choosing will intense and confirmed in good or in evil. Hence simply the voluntary and goodness or sin are increased. Hence St. Thomas says that one who sins from habit, that is, not from inadvertence or passion, but uses his habit by his free will alone, sins from mere malice. Hence two principles:

1. What is done advertently from an involuntary custom, or inadvertently from a voluntary custom, is under some respect more voluntary, but less free.

2. What is done advertently from a voluntary custom is not less free, but simply more voluntary.

97. Observation.

Good custom diminishes freedom toward evil; this, however, is an imperfection of the will; whence good custom perfects the will more.