 Let’s begin with events. Some have proposed that events are just regions of spacetime (Lemmon 1966; Quine 1985). That is: they propose that events are individuated by the time and place of their occurrence. This is a very coarse-grained view of events. According to it, no two distinct events can occur at the same place and time. To see why some think this individuates events too coarsely, consider the example form Davidson (1969): A metal ball is spun on a hotplate. As it rotates, the ball heats up. It heats up and rotates within precisely the same region of spacetime. So, if we individuate events in terms of the time and place of their occurrence, then we must say that the ball’s heating up and its rotation are one and the same event. But it can seem that the ball’s heating up and its rotation differ causally. The ball’s heating up caused the surroundings to warm, but it does not appear that the ball’s rotation caused the surroundings to warm. Similarly, the ball’s being spun caused it to rotate, but didn’t cause it to heat up. And the hotplate caused the ball to heat up, but didn’t cause it to rotate. Moved by examples like these, Davidson (1969) suggests individuating events by their causes and effects. That is, Davidson proposes that x and y are the same event iff, for every event z, both z caused x iff z caused y and x caused z iff y caused z. The left-to-right direction of this biconditional follows from the Indiscernability of Identicals, so the right-to-left is the substantive direction; it tells us that we should not draw any more distinctions between events than are needed to account for differences in causation. This imposes a constraint on how a theory of events must relate to a theory of causation, but on its own, it does not tell us what events are, nor how finely they are individuated. After all, without some additional claims about which events are causally related, Davidson’s thesis is entirely consistent with the claim that the ball’s rotation and its heating are identical.