  The first argument for moral liberty depends upon the inadequacy of any account of deliberation that leaves out the belief that our conduct is in our power. So the second depends upon the inadequacy of any account of what makes a person morally accountable that does not include the power to control action. Someone who wished to deny that human beings have power over their conduct, but are still morally accountable, might note, for instance, that one of the primary purposes of certain forms of punishment, most notably imprisonment, is to prevent the offender from acting similarly in the future. However, such a purpose does not presuppose that the person has power over his or her conduct. If the thief is going to steal again, then that's reason enough to imprison him, we might say. This is so even if he is going to steal only because his desires will inevitably give rise to such behavior and not because he has power that he is resolved to exercise objectionably in the future. Reid's second argument for moral liberty fails if purposes of this sort exhaust the purposes of punishment. The second argument turns, that is, on a retributivist conception of punishment—a conception according to which a punishment is appropriate only if it is deserved—and a further claim to the effect that a punishment is never deserved in the retributivist's sense if the crime was not efficiently caused by the agent to whom the punishment is issued. It remains an open question whether or not a retributivist conception of punishment could be coherently married to a view that denies that human beings are endowed with power. Reid's second argument for moral liberty raises this question in a powerful form.