 But what more must be added? Agent-causal libertarians maintain that self-determination requires that the agent herself play a causal role over and above the causal role played by her reasons. Some agent-causal libertarians deny that an agent’s reasons play any direct causal role in bringing about an agent’s self-determined actions (Chisholm 1966; O’Connor 2000, ch. 5), whereas others allow or even require that self-determined actions be caused in part by the agent’s reasons (Clarke 2003, ch. 9; Steward 2012, ch. 3). But all agent-causal libertarians insist that exercises of the power of self-determination do not reduce to nondeterministic causation by apt mental states: agent-causation does not reduce to event-causation.