How we cite our quotes:
The boy lifted the [flare]gun from the case and held it. Can you shoot somebody with it? he said.
[The Man:] You could.
[The Boy:] Would it kill them?
[The Man:] No. But it might set them on fire.
[The Boy:] Is that why you got it?
[The Man:] Yes.
[The Boy:] Because there's nobody to signal to. Is there?
[The Man:] No. (333.14-333.21)
McCarthy gives us a good dose of irony here. (Take it, reader! It's good for you!) Instead of using the flare gun to signal other people, The Man figures he'll use it to set them on fire. As if the only form of communication left on the planet is violence. So a tool typically used to signal distress becomes a grisly weapon.