Tim, Tom, Time and Fate: Lewis on Time Travel

In his well-known time travel story, David Lewis claims that there is a sense in which Tim can go back in time and kill his Grandfather and a (more inclusive) sense in which he cannot. Lewis describes Tims predicament as semi-fatalist, but holds that this does not compromise Tims freedom or his ability to kill Grandfather. I argue that if semifatalism is true of Tim, it is true of everyone, and that this is a troubling conclusion.