  There are many ways of querying Ayer’s conclusion. Austin attacked the way he saw the argument from illusion being deployed. He questioned just about everything in it: the distinction between veridical and non-veridical perception, the supposed generalization from ‘some (real) perceptual experience is indiscriminable from a (mere) perceptual appearance’ to ‘all such perceptions are indiscriminable from their counterpart appearances’, and the assumption that when we have defective perceptions there are non-material objects of those perceptions, sense-data.