As a former addict, I know how hard it is to struggle with drug problems. And, as someone who has studied the issue of addiction for decades, I know that the question of addiction and responsibility-- what behavior is caused by the person, and what is due to the influence of the drug-- is not easily determined.
Some-- call them the disease model absolutists-- argue that anything an addict says or does under the influence isn't "really" under his control. In the case of Mel Gibson's recent drunken outburst, these folks claim that his anti-Semitic ravings were "just the drink talking."
Others-- and here I include myself-- argue that while addiction may exacerbate antisocial or immoral tendencies, it cannot create them afresh. If you aren't anti-Semitic to begin with, no amount of drink will cause you to start blaming the Jews for world problems.
If-- like most human beings, however-- you harbor some prejudices, drink may remove your inhibition from expressing them, but such disinhibition tends to produce the odd inappropriate comment, not a full-fledged rant. Continued spouting on the same theme, as Gibson did during his arrest, generally indicates that the issue has been given consideration, rather than simply being an errant impulse.
This question is important because it has far larger implications in determining appropriate drug policy, not just Gibson's moral status. If addicts have no control over their behavior while using, it is correct to take their civil liberties and treat them like children, incarcerating them until we can be sure that their better selves are back in control.
If, on the other hand, addicts' wills are merely impaired by drink or drug, the issue becomes more complicated. If addiction responded to plain-old reward/punishment learning, it actually couldn't exist: addiction is defined as compulsive use of a substance *despite* negative consequences, so merely increasing the negative consequences one experiences as a result of drugs is unlikely to solve the problem.
Alternatively, if addiction were completely unresponsive to contingencies, recovery would be impossible-- no amount of punishment for using or reward for staying clean would have any influence.
We're left with a tricky situation in which addicts have some control over their behavior-- and therefore some responsibility for it and the attendant level of civil rights and responsibilities-- but not as much as they might have were they not under the influence. Further complicating matters is the fact that the substance itself, the social setting and the mental state of the addict all play roles as well-- and so, the amount of control an addict has may fluctuate.
And, to make it even more complicated, the same things that predispose people to addiction may also predispose them to lesser moral control over their behavior. Take, for example, a child raised in a violent, abusive home in a crime-ridden neighborhood. Living with violence causes the stress system to be constantly on-guard-- this prompts a quick reaction to threat, which is needed to protect yourself when you are constantly at risk of being attacked.
However, when you are not under threat-- say, in school-- you will still have this hair-trigger threat response, and may react aggressively to things that actually aren't threatening, for example, eye contact. This will set you up for being labeled a "behavior problem"-- and over time, if you continue to live with violence and continue to react aggressively, the brain areas which are supposed to reign in the threat response will become under-developed as the rapid-response threat regions get over-developed.
Further, your dysregulated stress system will make drugs attractive to you-- and the fact that you've been labeled a behavior problem means that you will probably hang around with other similarly-labeled kids (the "nice" kids will be afraid of you) and be exposed to drugs. A vicious cycle can spiral out of control if no positive forces intervene.
Fast-forward ten years and this formerly abused child has become a violent mugger, crack addict and armed robber. Both the crime and the drugs are an outgrowth of the abuse, exacerbating each other, but the drugs didn't produce the crime and the crime didn't directly cause the drug use. In fact, if you look at it chronologically, in most such cases, the aggressive behavior and crime long precedes the addiction.
Get such a person sober, as they say in 12-step programs, and you have a sober thief--and, unless you address the underlying problems, not one who is likely to stay sober long.
In Mel Gibson's case, this means that while rehab may curtail his drinking, unless he takes seriously the idea of "moral inventory" suggested by 12-step programs or undergoes some other form of serious moral reflection, his anti-Semitism will remain untouched.
You can blame the drink for the disinhibition-- but you can't blame it for the ugliness it unmasks. A cynical "Now I'm in recovery; all should be forgiven" won't cut it without genuine amends. I have my problems with the way 12-step programs sometimes conflate moral and medical issues-- but in this instance, they've got a lot to teach. We'll see if someone like Gibson is capable of learning.