 Davidson notes the heavy dependence, in Ducasse’s account, on the notion of a ‘change’. And he asks whether we really have a purchase on this concept absent appeal to laws. There are two aspects of this concern. First, the notion of ‘change’ is short for ‘change of predicate’—a change occurs when a predicate true of some object (or not true of that object) ceases to be true (or comes to be true) of that object. And this leads directly to questions about how predicates are individuated and their relationship to laws (see below). Second, and at a more general level, the notion of ‘change’ has itself changed over time—for instance, Newtonian mechanics defines a change differently than Aristotelian physics, so that continuous motion counts as a change, and thus requires an explanation, according to the latter but not the former. Thus, the very notion of ‘change’ is theory dependent, and therefore (Davidson holds) presupposes the notion of ‘law’, in the sense that something counts as a change, and thus as having a cause, only against a background of theoretical principles.