I think the appeal of IIA loses some of its grip when one realizes that a lot of our ordinary moral intuitions violate it. Pete Graham has a nice case showing this. Here’s a slightly simplified version:
Suppose you see two people drowning in a crocodile-infested lake. You have two options:
Option 1: Do nothing.
Option 2: Dive in and save the first person’s life, at the cost of one of your legs.
In this case, most have the intuition that both options are permissible — while it’s certainly praiseworthy to sacrifice your leg to save someone’s life, it’s not obligatory to do so. Now suppose we add a third option to the mix:
Option 3: Dive in and save both people’s lives, at the cost of one of your legs.
Once we add option 3, most have the intuition that only options 1 and 3 are permissible, and that option 2 is now impermissible, contra IIA.
Thanks, this is an interesting example!
I think if you are a pure consequentialist then it is just a fact of the matter that there is a goodness ordering of the three options, and IIA seems compelling again. Perhaps IIA potentially breaks down a bit when one strays from pure consequentialism, I’d like to think about that a bit more.
Yeah, for sure. There are definitely plausible views (like pure consequentialism) that will reject these moral judgments and hold on to IIA.
But just to get clear on the dialectic, I wasn’t taking the salient question to be whether holding on to IIA is tenable. (Since there are plausible views that entail it, I think we can both agree it is!)
Rather, I was taking the salient question to be whether conflicting with IIA is itself a mark against a theory. And I take Pete’s example to tell against this thought, since upon reflection it seems like our ordinary moral judgments violate the IIA. And so, upon reflection, IIA is something we would need to be argued into accepting, not something that we should assume is true by default.
Taking a step back: on one way of looking at your initial post against person-affecting views, you can see the argument as boiling down to the fact that person-affecting views violate IIA. (I take this to be the thrust of Michael’s comment, above.) But if violating IIA isn’t a mark against a theory, then it’s not clear that this is a bad thing. (There might be plenty of other bad things about such views, of course, like the fact that they yield implausible verdicts in cases X, Y and Z. But if so, those would be the reasons for rejecting the view, not the fact that it violates IIA.)