 A few comments on the logic of the argument are in order.  (2)  and  (3)  make up the meat of the argument; together they entail  (4).  This means that  (1),  which is motivated by the skeptical scenarios mentioned above and the associated veil of perception view, would be unnecessary for deriving the skeptical conclusion, as are those skeptical scenarios, were it not for the fact that  (1)  is commonly taken to render perception inferential in such a way as to lend support to  (2).  If  (1)  is true, then, plausibly,  (2)  is: if our access is mediated by potentially nonveridical appearances, then we should only trust the appearances we have reason to think veridical. And no other reason to endorse  (2)  is immediately apparent (although an additional motivation for  (2)  will be discussed below, in  section 3.1).  (1) is therefore an important component of the traditional problem. The plausibility of  (3)  derives from the idea that our only means of verifying the veridicality of appearances would itself depend on perception, in the question-begging manner sketched above.