 In the argument below, ‘\(L\)’ is an abbreviation for a sentence expressing a conjunction of all the laws of nature; ‘\(H\)’ is a sentence expressing a true proposition about the total state of the world at some time in the distant past before any agents existed; ‘\(\Box\)’ is ‘it is logically necessary that’; ‘\(\supset\)’ is the material conditional, and ‘\(P\)’ is a dummy for which we may substitute any sentence which expresses a true proposition.