Friday, February 19, 2010

Externalism about prudential reasons

Consider this case, which a colleague tells me is standard. You are bleeding badly, and you need to get to the hospital. You get in your car. No ambulance is available. However, unbeknownst to you, your car's ignition is wired to a bomb. What should you, prudentially, do? Suppose you say "Don't go to the hospital, try to self-treat." Why would you say that? Well, it has better consequences than turning on the ignition. Call somebody who says this a "consequences externalist".

But what does it mean to say that it has better consequences than turning on the ignition? I suppose it's because something like this pair of conditionals is true:

  1. Were you to turn on the ignition, the bomb would explode and you'd die immediately.
  2. Were you not to turn on the ignition, you'd live longer.
But in fact we live in a world that, as far as we know, is suffused with indeterminism. There is a tiny chance that if you turn on the ignition, the electrons from the battery will quantum tunnel around the bomb's igniter and to the car's spark plug. There is a tiny chance that if you don't turn on the ignition, a quantum event will increase the heat in the bomb and make it explode. And so on.

If something like generalized standard Molinism (i.e., Molinism generalized to indeterministic stuff other than free will) is true, (1) and (2) are perfectly well defined. But suppose no such view is true. So, really, all we have at the time of the decision are objective probabilities: it is overwhelmingly likely, given the physical state of the world, that if you turn on the ignition, the bomb will explode and you'll die immediately, etc. So, it seems, the consequences externalist has to be deeming the conditionals true when the probabilities are high enough.

So, it seems, the consequences externalist is saying that you ought not to turn on the ignition because it is exceedingly likely, given the actual arrangement of the universe at the time of the action, that doing so will let you live longer, and it is exceedingly likely that turning on the ignition will not.

Fine. Now imagine that you in fact turn the ignition, the electrons quantum-tunnel around the bomb, and all is well (maybe eventually the bomb quantum-tunnels into the sun, too). This is exceedingly unlikely, but is compatible with everything in the story so far. According to the consequences externalist position I've sketched, you in fact did the wrong thing—even though it had better consequences than the alternative. You did the wrong thing, because at the time of the decision the objective probabilities were against this decision.

But to say that in this case you did the wrong thing goes against the guiding intuitions of the consequence externalist. Once you admit that you might have done the wrong thing even though it had the better consequences, you should probably just abandon the consequence externalism altogether, and move from objective to subjective probabilities.

Now, there is something the consequence externalist can say. She can say that we evaluate subjunctives by probabilities when their antecedents are false, and by consequents when the antecedents are true. This is messy, but not crazy. So, in the case I've described, (1) is false because it has a false consequent and true antecedent, but (2) is true because the objective probability of the consequent given the antecedent is low at the time of the action.

But if the consequence externalist says this, she has the following weird thing to say. She has to say that (a) turning on the ignition was in fact right, but (b) had you not turned on the ignition, turning on the ignition would have been wrong. Why does she have to say (b)? For if you had not turned on the ignition, the subjunctive conditional (1) would have been true. It would have been true because it would have had a false antecedent and hence would have to have been evaluated according to the objective probabilities.

So, oddly, you did the right thing, but had you not done it, it would have been the wrong thing. That is weird indeed.

5 comments:

enigMan said...

I like this case, it's weird but simple; but I wonder if the externalist is left with a result that is too odd. The world being indeterministic, in a non-Molinistic way, the externalist should think that what is objectively best changes, as the indetermined becomes determined.

This makes things more complicated than in the deterministic case, but no more paradoxical than indeterminism is anyway (e.g. via talk of what is true). And since what is objectively for the best is changing, it makes sense that doing what is objectively the wrong thing at the time can turn out to have been the objectively right thing.

And there are common intuitions that such is how things are, e.g. people who take risks do feel justified when (and just because) things work out well. Although I don't think that they should then pride themselves on having taken a risk, there can seem to be objective rewards for such behaviour (e.g. evolution).

Alexander R Pruss said...

Surely it can't both be the case at t1 that p, and at t2 that it was not the case that p at t1.

My suspicion is that consequence externalists haven't thought enough about the truth grounds of counterfactuals in an indeterministic world.

Maybe a slightly better way of running the case is this. You're wounded and in your car. There is no bomb in your car--in fact, your car is perfectly fine. What should you do? Intuitively: you should try to drive to the hospital, right? So, you turn the ignition, and the spark quantum tunnels from the spark plug to the gas tank, and, boom, you're dead.

If the counterfactuals are defined by probabilities, you should say that you did the right thing though it turned out bad. But that is a betrayal of what consequence externalists stand for. The other option is this weirdness:
1. You did the wrong thing. But:
2. Had you not done this, it would have been the wrong thing to do!

So, there is no thing such that had you done it, it would have been right.

You did the wrong thing by turning the ignition instead of self-treating. The right thing to do was to self-treat. But had you done the right thing, it would have been wrong!

enigMan said...

I do find myself more convinced by your second example; I would agree that then one did the right thing, which happened to turn out badly. But could the consequence externalist not also say that one did what was the right thing to do at the time? The actual consequence would have to remain important, but I still don't see why that could not enter into things as the effect of hindsight.

Could the consequence externalist not say that while it was the wrong thing to do as it happened, it was the right thing to do at the time? There may be a prima facie contradiction there, but under Presentism (which is a nice way to think of such non-Molinistic indeterminism) the actual consequence did not exist at the time. I think that to be a consequence externalist one only has to allow for such consequences as exist; and if there is such indeterminism then the consequences change, from lots of objective possibilities to actual outcomes.

Then the consequence externalist could say:
1. You did the wrong thing (as it happened). But:
2. It was the right thing to do (at the time). And:
3. Had you not done this, then that would have been the wrong thing to do (at the time). Although of course:
4. That might have turned out to have been the right thing to have done, given the ubiquity of the indeterministic physics; so there is something such that had you done it, it would have been right.

enigMan said...

...although I wonder whether the prima facie contradiction between 1 and 2 (which might be resolved by distinguishing more clearly between our actions and what randomly happens to us) would rather make the consequence externalist suppose that generalized standard Molinism is true.

Alexander R Pruss said...

Sociologically, few philosophers (and almost no non-theist philosophers--that's an odd sociological fact) are going to accept either Molinism or presentism. I agree that either one of the two will get one out of the difficulty.