The bomb won’t kill me regardless of whether I take precautions.This sentence looks rather harmless but is in fact ambiguous in a subtle way, which proves to be the root of the problem. Thus, read in one way—a so-called “thick” way—the sentence implies that it is unnecessary to take precautions against the bomb, as indeed the reasoning above proceeds immediately to infer. (See just after the yellow bit.)
If the bomb won’t kill me, then the bomb won’t kill me regardless of whether I take precautions …this being the only way to justify this opening claim, but then surreptitiously switches to using it in the thick way:
… the bomb won’t kill me regardless of whether I take precautions; so any precautions I take will be unnecessary.the switch now being required to justify this closing claim. This, of course, is the fallacy of equivocation: that of changing meanings midway through an argument. The intent was clearly to merge the two claims just shown and derive:
If the bomb won’t kill me, then any precautions I take will be unnecessarythis being a key claim of the larger argument. But the derivation is now seen to be fallacious, based as it is on an equivocation. (This is essentially the diagnosis given by Dummett himself.)
If Ireland already won, then any waiting that you do will be unnecessaryrests illegitimately upon the resulting equivocation. All of this is exactly as before.