Howard Robinson "The Failure of Disjunctivism to deal with “Philosophers’ Hallucinations”"

Philosophers are (mainly, at least) interested in what I shall call “philosophers’ hallucinations”. These are not, as far as we know, hallucinations as they actually occur, but they are, it is argued, the hallucinations that would occur if the perceptual system and brain were stimulated in the just the way it is stimulated in genuine perception, but directly and not by the usual external objects. This would give, it is supposed, an hallucination indistinguishable to the subject from the corresponding perception.

A belief in the possibility of such hallucinations is taken as grounds for rejecting naïve or direct realism, and, perhaps, for adopting the sense-datum theory. Defenders of direct realism but who accept the possibility of philosophers’ hallucinations are obliged to adopt the disjunctive theory of perception. In this paper, first I shall restate the (as far as I can see) usually ignored prima facie reason for thinking that disjunctivism is grossly implausible. Then I shall discuss critically the contemporary versions of disjuctivism defended by John McDowell, Michael Martin (and maybe others).