  What we've seen is that Clarke's conception of what it is to be a free agent requires first that the agent may act in some particular way even in the absence of his having a sufficient reason to act in that particular way. Thus, there are exceptions to PSR. Second, we've seen that when the agent has a sufficient reason to do a particular act and freely does that act, the sufficient reason or motive is not a determining cause of the agent's act. At the time of the act the agent had the power not to perform that act. So, on Clarke's libertarian view there is a profound difference between the sufficient reason for the balance moving in a particular way and the sufficient reason for an agent's free act. In the first case the sufficient reason is a determining cause, in the second it is not. Leibniz, however, sees no need to suppose there are exceptions to PSR and no need to treat the motive for the agent's free act as anything other than a determining cause of that act.