Offers the Switching Argument for the claim, (2), that only reason-giving relations between perceptual experiences and empirical beliefs could possibly serve the content-determining role required by (1). Non-reason-giving relations between perceptual experiences and basic empirical beliefs would necessarily leave the subject quite ignorant of which mind-independent object his belief is supposed to be about, in a way that is incompatible with his having the understanding required for this to be a belief of his, about just that thing, at all. Along with the assumption that we have beliefs about a mind-independent spatial world, (1) and (2) entail (R), that perceptual experiences provide reasons for empirical beliefs, the main thesis of Part I of the book.
Keywords: empirical belief, perceptual experiences, reason-giving relations, Switching Argument