[jrkatz]

I'm sorry, I should have been clear. The 'certainty of punishment' bit should be understood as a probability. The gist of it is that a person considering criminal behavior isn't worried about the severity of the punishment `S` in isolation, but also the likelihood (read: 'certainty') `C` thereof. Simplistically the deterrence model is `C*S`. An extremely severe punishment (execution!) with zero or effectively zero chance of getting caught provides no deterrence. There's more to it - for example doubling severity does not double deterrence in general - but that's the gist of it.

My little thought experiment supposes a person who is drunk evaluates, before deciding to get in the car, the potential outcomes of drunk drive, while entirely convinced they won't harm someone. (I suspect most drunk drives are entirely convinced they won't harm someone, although it is obvious to anybody else there is at least a _chance_ they will.) Today, getting caught with whatever nonzero probability results in a punishment of some severity. By the model we're assuming above, this produces a nonzero amount of deterrence. If we shift away from punishing drunk drivers, the severity drops to zero. If a drunk's options are to call for a ride from the bar or try to drive home, and getting caught at the latter only mean they'll have to call for a ride from some location between the bar and home, driving is the rational choice after all, _so long as they are convinced they won't hurt anybody_.

I was being too circumspect. The point of my scenario is to highlight that decriminalizing drunk driving will likely increase the amount of drunk driving, at least among the population of drunk drivers who are overconfident in their abilities. That in turn will increase the danger drunk drivers present to the rest of us.

I gather you think reaction is morally preferable to prevention in such cases. Is that a fair assertion? In general, I bet we agree there is some amount of risk to myself that I must tolerate to afford others their freedoms, and have just landed at different risk tolerances. I try to take need into account when drawing my line in the sand. "Does anybody _need_ to drive drunk?". Since it's a situation drunk drivers make for themselves I'm happy to punish it. How do you draw your line?

[pdonis]

> My little thought experiment supposes a person who is drunk evaluates, before deciding to get in the car, the potential outcomes of drunk drive, while entirely convinced they won't harm someone.

And just that last clause makes it clear that, at least at that time and place, that person is not going to be deterred by reasonable incentives against reckless behavior, because their judgment is impaired.

Basically, your solution (which is also, as you point out, the solution in place in our current society), is to put unreasonable incentives in place--unreasonable from the point of view of the person, because, in your hypothetical, they're 100% convinced they won't harm anyone, so to them this whole "don't drive drunk" thing seems like an unreasonable restriction. It might be reasonable from the point of view of society, but that very view of "society" is not really compatible with a free society of free and responsible adults. More on that below.

> I gather you think reaction is morally preferable to prevention in such cases. Is that a fair assertion?

The only moral principle I have stated is that one should not impose punishments on people who have not caused actual harm. But I did imply a corresponding moral responsibility for the people themselves: that they should exercise reasonable judgment when making choices. People who either will not or cannot take on that responsibility are not going to be deterrable by the kinds of reasonable incentives I am proposing.

Your position seems to be, basically, that in our current society, most people fall into the latter category: they either will not or cannot take responsibility for exercising reasonable judgment--for example, by making it an ironclad rule for themselves that if they are going to go someplace where they might get drunk, they have a plan in place in advance to get home without having to drive. If most citizens of our supposedly free society can't meet that standard, we have a much worse problem than drunk driving.

> Since it's a situation drunk drivers make for themselves I'm happy to punish it.

I don't disagree that being in a situation where you "need" to drive drunk is self-inflicted; I basically said the same thing just above. My point is broader: that our society seems to assume that most adult citizens, if not prevented by various nanny-state laws, will make such errors of judgment frequently enough for it to be a problem. Either that assumption is false, in which case our society is imposing huge restrictions on people that are not justified; or, even worse, that assumption is true, in which case I think our society is doomed.

[jrkatz]

> The only moral principle I have stated is that one should not impose punishments on people who have not caused actual harm

But isn't the risk of death a harm? That's what I'm driving at here. It's about where the line is drawn.

Should it be legal for someone to take shots at you as long as they miss? Drunk driving is the tip of an iceberg here.

> My point is broader: that our society seems to assume that most adult citizens, if not prevented by various nanny-state laws, will make such errors of judgment frequently enough for it to be a problem. Either that assumption is false, in which case our society is imposing huge restrictions on people that are not justified; or, even worse, that assumption is true, in which case I think our society is doomed.

This bit about a doomed society interests me. Why must society be doomed if it needs "nanny-state" laws to function? If society needs those to function and it makes them (society produces its own laws, after all), isn't that the look of a society that is succeeding? A society that regulation and fails to self-regulate is doomed, for sure.

Now then, the bit about 'most' adults needing such help doesn't come from anywhere. I agree it's a few. But if most adults don't need government incentive to drive sober, regulation preventing drunk driving abrogates a 'right' _they won't exercise_. Are their freedoms limited in that case? Or are laws against drunk driving highly targeted, impacting only the people who are driving drunk, getting them off the roads before they hurt someone?