It has often been claimed, and it is widely agreed, that agency involves the initiation of action by the agent.[7] But it has been controversial what this consists in. The standard conception is compatible with the claim that intentional actions are initiated by the agent, and proponents of the standard theory have argued that initiation can be explained in terms of causation by the agent’s mental states and events. According to desire-belief versions of the view, initiation by the agent consists in causation by the relevant desire-belief pairs (Goldman 1970; Davidson 1971; Dretske 1988). According to more recent versions, initiation consists in causation by the relevant intentions (Brand 1984; Bratman 1987; Bishop 1989; Mele 1992, 2003; Enç 2003). Opponents of the standard conception argue, however, that an agent’s power to initiate action cannot be reduced to the capacity to act intentionally and for reasons. They argue that the exercise of agency may be entirely spontaneous, in the sense that an agent may initiate an action for no reason and without prior intent. On this view, reasons and intentions may have a strong and even a decisive influence on how an agent acts. But agency has its source in the power to initiate, and the exercise of this power cannot be reduced to the agent’s being moved by reasons or intentions. This is an alternative conception of agency (Ginet 1990; O’Connor 2000; Lowe 2008; see also McCann 1998; for critical discussion see Mele 2003: 38–51, 71–76; Clarke 2003: 17–24). Proponents of this alternative conception reject the standard theory and they reject, more generally, any account of agency in terms of causal relations between agent-involving states and events. According to some, the initiation of action consists in irreducible agent-causation, others appeal to uncaused mental acts of the will. The main positions on this issue correspond to the main positions in the metaphysics of agency, to which we turn in section 3.1.