The Worlds We Have Already Destroyed

"If the only weapon that protects us functions entirely in an imaginary world, a world in which we would have pulled the trigger, what do we truly know about the solidity of that protection? This is a question no experiment can settle for us." Here we attempt to set out the theses of Jean-Pierre Dupuy, David Lewis, and Gregory Kavka on a complex subject: counterfactual propositions and their application to possible worlds.