November 17

An example of a counterfactual condition is the following: ``If McCain had won in 2008, then Joe Biden would have been vice president.'' Normally, we would look upon this as an if-then sentence, if P then Q. The P here is false and the Q is true, so by convention, we would say that the sentence is true. On the other hand, this doesn't seem to capture the real meaning of the sentence. To one who has not been handicapped by a semester of logic, this sentence has something fundamentally wrong with it. Common sense would tell us that if McCain had won, Sarah Palin would have been vice president, not Joe Biden.

This sentence cannot be adequately understood without considering alternative universes: worlds in which the P (``McCain wins'') is true. Jim 1 asks Jim 2 who won in 2008 in his universe. Jim 2 says Obama. Jim 1 suggests using the time machine to search for more alternative universes, hoping to find one where McCain won. Tom 1 and Tom 2 think this is dangerously stupid. If you agree with Jim 1, Click here. If you are a stick-in-the-mud, Click here.