 A classic criticism of foundationalism now arises, a version of the infamous  Sellarsian dilemma.  Must you know that your (say) vision is reliable to be justified in believing that there’s a door in front of you on the basis of its looking that way? If so, we face the first horn of the dilemma: the regress of justification is revived. For what justifies your belief that your vision is reliable? Appealing to previous cases where your vision proved reliable just pushes things back a step, since the same problem now arises for the reliability of your memory. Could we say instead that the appearance of a door is enough by itself to justify your belief in the door? Then we face the second horn: such a belief would seem to be arbitrary, formed on the basis of a source you have no reason to trust, namely your vision (Sellars 1956; Bonjour 1985; Cohen 2002).