More fatalism

In response to my previous post, Jonathan Ichikawa offered a more puzzling variant of the fatalist argument. International tensions are high, and a captain spies a foreign frigate off his starboard. He reasons,

1. Either there will be a battle or there won’t be a battle.
2. If there will be a battle, there’s no harm in firing the cannons now.
3. If there won’t be a battle, there’s no harm in firing the cannons now.
4. So, there’s no harm in firing the cannons now.

Something is wrong here.

“There’s no harm in firing the cannons now” means something like “Firing the cannons now will lead to no worse consequences than doing otherwise.” Now let’s suppose that “if” expresses a material conditional. Then the argument is valid. But the world could be like this:

• The captain fires the cannons. It starts a battle, which leads to a terrible war and thousands of ugly deaths. If the captain hadn’t fired the cannons, none of this would have happened.

In this case, the first premise is true. The third premise is also true, because the antecedent is false. But the second premise is false: there will be a battle, but there’s very great harm in firing the cannons now. Moreover, whatever “if” means, it means something at least as strong as the material conditional. So Premise 2 really is false in the war-world.

Then why does it sound true? Probably because we naturally hear it as saying something like “If there will be a battle anyway, there’s no harm in firing the cannons now.” That is, we implicitly give the antecedent some kind of modal force.

• If (necessarily, there will be a battle), then there’s no harm in firing the cannons now.

This is true: if the battle is inevitable, the captain might as well take the first shot. But the reasoning fails precisely because the battle is not inevitable: the antecedent of this conditional is false.

There may be something more general going on here: maybe when someone says “It will be the case that P”, in general we hear this as saying “No matter what, it will be the case that P”. Maybe “will” even has this modal force as part of its content. On this alternative story, Premise 2 is true after all, and the fatalist argument shows roughly what the fatalist thinks it shows: in general, “There will be a battle or there won’t be a battle” is false! But this does not mean that the future is “open”: rather it means that this is false:

• Necessarily, there WILL be a battle, or, necessarily, there WILL not be a battle.

Where “WILL” is an artificial version of “will”, with all of the modal overtones stripped out—it means merely “at some future time”. If something like this semantic story is true, it would explain a lot of our confusions about the future: our language naturally leads us to confuse tense with modality.