In Memoriam

I remember distinctly the moment I learned that David Lewis had died. It was during my years as a postdoctoral fellow, when I was more than a little isolated, and so it turned out to have been some time—months, maybe—since the event. I recall thinking: the world in which I thought I was living, during those months, turned out not to be the actual world, and so I turned out not to be the person I thought I was, but merely a counterpart of that person. And thus arose the half-formed thought (still only half-formed now, alas) that therein lay some insight into what is actually at stake in the conflict between counterpart theory and transworld identity.