"No, the difference between the two sentences li..."


by Kevin Van Horn Dec 27 2017

If $~$K$~$ denotes the proposition that somebody else shot Kennedy and $~$O$~$ denotes the proposition that Oswald shot him, then the first sentence and second sentence are respectively talking about:

No, the difference between the two sentences lies entirely in the background information assumed. The first sentence implicitly assumes background information B that includes the fact that someone did, in fact, shoot JFK. The second sentence implicitly assumes that we have some sort of structural equation model (as discussed in Pearl's book Causality) from which we can show that JFK must have been shot -- even if we exclude from our background information all events occurring on or after November 22, 1963.