 In the older literature, there were just two kinds of incompatibilists—hard determinists and libertarians. A hard determinist is an incompatibilist who believes that determinism is in fact true (or, perhaps, that it is close enough to being true so far as we are concerned, in the ways relevant to free will) and because of this we lack free will (Holbach 1770; Wegner 2003). A libertarian is an incompatibilist who believes that we in fact have free will and this entails that determinism is false, in the right kind of way (van Inwagen 1983). Traditionally, libertarians have believed that “the right kind of way” requires that agents have a special and mysterious causal power not had by anything else in nature: a godlike power to be an uncaused cause of changes in the world (Chisholm 1964). Libertarians who hold this view are committed, it seems, to the claim that free will is possible only at worlds that are at least partly lawless, and that our world is such a world (but see O’Connor 2000, Clarke 2003 and Steward 2012). But in the contemporary literature there are incompatibilists who avoid such risky metaphysical claims by arguing that free will is possible at worlds where some of our actions have indeterministic event causes (Kane 1996, 1999, 2008, 2011a; Ekstrom 2000; Balaguer 2010; Franklin 2018) or that free will is possible at worlds where some of our actions are uncaused (Ginet 1990). Note that none of these three kinds of incompatibilists (agent-causation theorists, indeterministic event-causation theorists, non-causal theorists) need be libertarians. They may reserve judgment about the truth or falsity of determinism and therefore reserve judgment about whether or not we in fact have free will. They might also be hard determinists because they believe that determinism is in fact true. But what they do believe—what makes them incompatibilists—is that it is possible for us to have free will and that our having free will depends on a contingent fact about the laws that govern the universe: that they are indeterministic in the right kind of way. (See the entry on  incompatibilist theories of free will).