An event is anything that happens, an occurrence. The idea of an event began to take on a philosophical life of its own in the twentieth century, due to a reawakening of interest in the concept of change, to which the concept of an event seems inextricably tied, and to the growing use of the concept of an event in scientific and metascientific writing (see Broad 1933, McTaggart 1927, and Whitehead 1929). Interest in events has also been sparked by versions of the mind-body identity thesis formulated in terms of events and by the idea that a clearer picture of events will facilitate discussion of other philosophical issues.

Discussions of events have focused on whether there are events and, if so, what the nature of events is. Since whether there are events depends in part on what they would be like if there were any, the two issues have...