 What needs to be noted at this point is that Davidson argued early on for the claim that mental events have causal efficacy, through noting a problem for non-causal accounts of action explanation (Davidson 1963). Mental events and states explain action by making it intelligible—rational—in light of the agent’s beliefs and purposes. The challenge that Davidson raised for non-causal theories of action explanation was to account for the fact that, for any action performed, there may well be a large number of mental events and states true of the agent, and capable of rationalizing the action, but that don’t thereby explain that action. The agent acted because of some specific beliefs and purposes, but other beliefs and purposes of his could just as easily rationalize that action, and thus be cited in its explanation. Was the agent moving his hand as he did because he wanted to swat the fly, relieve a cramp, or wave in greeting? He may well have wanted to achieve all three of these aims, but still only in fact performed the action because of one of these reasons. How do we understand ‘because’ so as to rule out the pretenders? Davidson’s claim was that it is only if we understand ‘because’ as ‘was caused by’ that we can justifiably pick out the genuine explanans—thereby imputing causal potency to mental events.