Michael Williams has frequently considered and rejected approaches to "our knowledge of the external world" that see it as the best explanation for certain features of experience. This paper examines the salience of his position to approaches such as Mackie’s that do not deny the presentational directness of ordinary experience but do permit a gap between how things appear and how they are that allows for sceptical doubts. Williams’ main argument is that, to do justice to its place in a (...) foundationalist strategy, the external world as hypothesis must offer an explicandum that does not invoke concepts of objects but is rather purely experiential. He next claims that no coherent regularities are available at such a level so there is nothing to be explained. Coherence only comes with objects, not as something objects could explain. Confronting this with Mackie’s Lockean theory of perception, we find that Mackie decisively rejects the first claim about the nature of the explicandum, since he sees ordinary perception as involving intentional objects which are distinct from the persisting objects they present. He is also committed to rejecting Williams’ line on purely experiential regularities, though this plays a subordinate role in his general position. The crucial issue then becomes the tenability of Mackie’s intentional object analysis and the extent to which it might yet tilt the argument in favour of realism against a global sceptic. In formulating his own epistemological strategies Williams might appear to countenance a version of Mackie’s view divorced from foundationalism. But while Williams’ contextualism in its minimal version might do so, in practice it retains the lessons derived from his skirmishes with scepticism and thus disallows certain types of enquiry. I conclude by contrasting Mackie’s response to scepticism with that of Williams in his diagnostic vein. (shrink)