 NRB denies the skeptic accepts doctrines on the basis of any premises that purport to warrant them. On this view, [i] inapprehensibility and [ii] universal suspension were the residual and rationally unwarranted beliefs Arcesilaus was left with as a result of his philosophical activity (see Frede 1979 &amp; 1984, Cooper 2004, Brittain 2005 [2008], and Thorsrud 2009).