I’ve just got back from the University of Connecticut, where I gave my paper on Modal Knowledge at the Philosophy Department Colloquium and got lots of helpful feedback. The UConn grad students have just started a blog, What Is It Like To Be a Blog?.
I also attended a conference on Conditionals. On Saturday, Dorothy Edgington told us what she thinks about subjunctive conditionals, namely that they do not have truth values but rather express the speaker’s belief that the conditional probability of the consequent on the antecedent is high (i.e., basically, they function pretty much the way she thinks indicatives do, but in a different tense).
I was worried that there seem to be cases where the consequent is unlikely to be true given that the antecedent is, yet still would be true if the antecedent was. The existence of such cases suggests that subjunctives and conditional probabilities are not correlated in the way Edgington claims. We discussed the following example (one suggested by Edgington when I raised my worry in discussion time). Suppose you decide at the last minute not to get on a plane which is very unlikely to crash, and the plane in fact crashes, killing all its passengers. It’s tempting to think that the probability of your dying conditional on having got on the plane is low, because the plane’s chances of crashing were low, yet clearly if you had got on the plane you would have died.
Edgington replied that we simply have to find the right conditional probability, in much the same way that (say) someone who likes closest-world semantics for these conditionals has to find the right similarity relation. In the above case, she said, the right conditional probability is that of your dying given that you got on the plane and it crashed. To save the proposal, you just need to find the right pieces of further information about the world to take into account, besides what is mentioned in the antecedent. This information will makes the conditional probability of the consequent high.
This might be thought to be a bit ad hoc, given that the crashing is not mentioned in the antecedent of the conditional we’re actually interested in. But regardless of that, I think it is a problem that the response won’t always work if there is indeterminacy in the world. For in that case, there will – or at least, could – be some unlikely events that just happen, and are not rendered any more likely however much further information about the world we take into account.
Suppose C is an event that would have happened, without being determined, if A had happened, although it was very unlikely to do so. Then the subjunctive:
If A had happened then C would have happened
looks true, although the conditional probability of C on A is low. And in this case there is no further information about the world that we can take into account which will make the conditional probability of C high – that is, there is nothing which can play the role played by the fact that the plane crashed in Edgington’s response to the first example.
So Edgington’s account of counterfactuals seems at risk of giving the wrong results unless we assume there is no indeterminacy. And this seems to be a distinctive problem for the account, not analogous to an problem faced by closest-world approaches.