Aristotle, answered from the texts and cited to the page.
Substance abuse — the habitual pursuit of bodily pleasures through drink, drugs, or similar means to the point where reason loses its governance over action — is, in my framework, a case that sits at the intersection of akrasia (lack of self-control) and akolasia (self-indulgence), and the distinction between them matters considerably for how one understands the condition and whether it admits of cure.
Consider first the man who drinks to excess knowing full well that he ought not. He is like the person who gets drunk quickly on a small amount of wine — overcome by passion before reason can assemble itself to resist.1 His condition is akrasia: he acts contrary to his own decision, swept away by appetite. What is significant here is that the starting point — the correct opinion about what is good — is preserved in him, even if passion temporarily overwhelms it.2
Because that starting point survives, he can be persuaded to change; the condition is not incurable.3 The graver case is the man who has, through long habituation, arrived at the conviction that the pleasure of intoxication is simply what he ought to pursue. Vice, I argued, is in accordance with decision, while lack of self-control is contrary to it.4
The habitual substance abuser who no longer experiences his pursuit as a lapse — who feels no conflict, no repentance — has crossed from akrasia into something closer to akolasia. His starting point has been corrupted. And here the analogy to chronic disease is exact: such a condition resembles dropsy or tuberculosis, a permanent disorder, whereas the akratic case is more like epilepsy, intermittent and therefore more tractable.5
Character itself — ethos — develops through habituation, through repeated movements of the soul in one direction or another.6 The stone, however many times you hurl it upward, will never rise of its own accord; but the soul, precisely because it is not a stone, can be shaped.7 Virtue and vice are both brought about and destroyed by the same factors applied differently — pleasures and pains are the medium through which all such formation and deformation works.8
This is why discipline, understood as a form of treatment, operates through opposites: the man whose character has been bent toward excess must be trained back through the experience of restraint, not merely instructed in it. The practical implication is that one must diagnose which condition is present before prescribing any remedy. The akratic abuser, who retains his correct opinion about the starting point, is amenable to argument and persuasion in a way the self-indulgent man is not.9
The latter requires something more like the re-formation of character from the ground up — a longer and less certain work.
for the incontinent man is like the people who get drunk quickly and on little wine, i.e. on less than most people.Nicomachean Ethics
He is better than the undisciplined man and not unqualifiedly base. For what is best in him, the starting point, is preserved.Eudemian Ethics, pp. 142–143
it is on the contrary the former that is easily persuaded to change his mind, while the latter is not.Nicomachean Ethics
incontinence is contrary to choice while vice is in accordance with choiceNicomachean Ethics
wickedness is like a disease such as dropsy or consumption, while incontinence is like epilepsy; the former is a permanent, the latter an intermittent badness.Nicomachean Ethics
Character exists, as the name signifies, because it develops from habit, and a thing gets habituated as a result of a pattern of conduct that is not innate, by repeated movement of one sort or another.Eudemian Ethics, p. 51
We do not see this in lifeless entities: however many times you hurl a stone upwards, it will never do this without being forced to.Eudemian Ethics, p. 51
virtue and vice are concerned with pleasures and pains, since it is through these that discipline works, being a form of treatment that is (as in other cases) effected through opposites.Eudemian Ethics, p. 51
Since the uncontrolled man is not the sort to pursue through conviction bodily pleasures that are excessive and in conflict with correct reasoning, while the other kind of man has conviction, since he is just the sort to pursue them, the former can easily be changed by persuasion but the latter cannot.Eudemian Ethics, pp. 142–143