As usual, Ioan gets what I'm trying to say and says it better than I do!
Biological insanity, be it schizophrenia or psychosis or some other psychiatric disorder, is not intentional. The afflicted person is not 'immoral' because he does not choose to break with reality. I think the civil law here in the US has this approach, when it rules that 'legal insanity' is the inability to discern right from wrong.
I think that this is half-right: the psychiatric patient is most often trying to do the right thing, but with the wrong information. He tries to be moral, but just does not have the ability to make good decisions because of the impairment he experiences. He is not making 'stupid' decisions in the sense of being carefree or, as Ioan points out, intentionally stupid.
There is another kind of insanity, a moral insanity. This is "doing insane things for the sake of doing insane things." This insanity is intentional, done with full knowledge of what is true, and thus moral.
Morality is the description of behavior that is according to nature, thus according to what is right and good. Immorality is not a random act, but an intention to rebel against the natural order. When we know what is good but refuse to act accordingly, we are departing into moral insanity.
The addict often starts off in the arena of moral insanity. He will drink or use knowing that what he is doing is perhaps against morality, but his pride (driven by pain and fear) tells him he is entitled to act out in an immoral manner.
However, once the disease sets in and his intellect is sufficiently distorted, he enters into a type of biological insanity where his free will is impaired by a disease which he has no control of. Addiction has one foot in each type of insanity. One is treatable through a therapeutic and rational process, but the other is not. Biological insanity cannot be counselled, but moral insanity can.
The difficulty is being able to discern when the addict is acting out of either type of insanity. Does he have a choice not to drink or use? This is a tricky question: on the one hand, his moral insanity is treatable and so he does have a choice, yet his biological insanity compels him to use beyond his ability to control. The addict must learn to take responsibility for his intentional insanity, and leave the treatment of his biological insanity to the care of God. This is what the 12 Steps does.
However, there are many people who do "insane things for the sake of doing insane things." They are purposefully immoral. They have no biological impairment, and so they are truly insane. The person with biological insanity, if he can be properly treated, willingly embraces sanity in the same proportion as the general public (with perhaps a higher level of compassion and virtue on account of his experience of suffering with his disease). But, those who are purposefully immoral have a curable problem which only needs willingness.
My greatest concern for our modern world is that we are working overtime to redefine good in such a way that makes addictions recovery and true morality an impossibility. Our cultures stokes the fires of personal irresponsibility and self-indulgence even when it talks about altruistic notions of community and charity.
We arrest and fine people for destroying unborn turtles in their eggs because it is killing an endangered species, but say that abortion does not kill a human being. But, then again, we send people to prison for murder should they cause a woman to miscarry even in her first trimester, when it is perfectly legal for her to abort the child.
Why such a conflicted logic? Because we have become imprisoned by our desires for things, and are willing to abandon reason and logic for the sake of our goals: avoiding the consequences of voluntary, unprotected sex.
Abortion is just one example of many. So, how is it that we can teach the addict about morality when his own world is so distorted by immorality? We celebrate "doing insane things for the sake of doing insane things." Just look at the celebrity culture! Turn on your TV and watch what is going on.
The world is "doing insane things for the sake of doing insane things." We revel in our lawlessness, yet we wonder why we need to medicate ourselves.