Williams, Bernard Arthur Owen (1929–2003)

3. Internal and external reasons

For Kant, once I know that something is the right thing to do (which I am supposed to be able to do by pure reason alone, uninfluenced by desire), this alone supplies me with a reason for action. This Williams resists. He calls such reasons ‘external’ reasons, and wants to argue, by contrast, that reason can only motivate me if it is connected to some already existing motivational state of myself (such as a desire). Such reasons Williams calls ‘internal’ reasons, because they follow from something internal to the agent. Williams’ terminology here needs care and is liable to be confusing as he uses these terms in a different manner and with opposite effect than most philosophers (for whom ‘internal’ is taken to mean internal not to the person, but to morality; in the standard use, a reason based on antecedent desire is hence ‘external’).

In Williams’ terminology, all reasons (that is, all real reasons) are internal reasons. That something, for example, follows from the rationally apprehended supposed requirements of justice gives me in itself no reason to do it. I only have a reason if I also happen to want to be just. For Williams it is the same with prudence. Some philosophers, such as Sidgwick, argue that I am rationally required to regard all times to be of equal value; Williams, by contrast, argues that I only have a reason to consider the distant future as important as the near future if I happen to have a particular kind of prudential psychology. Again, what counts as a reason for me depends upon my own idiosyncratic psychological state; pure reason alone is unable to tell me what to do (see Moral motivation).