The practicality argument in its only tenable – ‘extreme’ – form is, if our foregoing conclusions are correct, an attack on the view that moral obligation constitutes an ‘external reason’ (in Williams’ sense) for action. For such a view, as our original investigations had suggested, involves the – for naturalists absurd – idea that an ‘inert’ fact about the world – the fact which makes the corresponding moral judgement true – can prompt an agent to act independently of any subjective motivations she might have. Before we can consider further the merits of the naturalist case, it is necessary to clear up one point in our interpretation of Williams. Williams, we have noted, is concerned with reasons in general. So far we have assumed that we may take what he says and apply it without more ado to the moral context. However, he issues a caveat (1981: 106) to the effect that we should not just assume that his question about the status of ‘external reasons’ is ‘undoubtedly the same as’ that concerning the status of the moral ‘ought’. But it is not entirely clear why he issues this caveat. After all, by his own account (ibid.: 110) the ‘external reasons’ theorist ‘wants any rational agent, as such, to acknowledge the requirement to do the thing in question’. In other words, the whole point about an ‘external reason’ seems to be that it applies categorically, or irrespective of an individual’s desires or other subjective motivations; for these will typically differ from person to person depending on a whole variety of contingencies. It cannot therefore be the categorical nature of the moral ‘ought’ that is the obstacle to applying Williams’ findings about reasons in general to morality in particular. In any case, we have our own independent grounds for maintaining that if morality is to have a special categorical force, the reasons it gives for action must be conceived as ‘external’ in precisely Williams’ sense.