They do not see that the return to perceptual experience, in so far as it is a consequential and radical reform, puts out of court all forms of realism, that is to say, all philosophies which leave consciousness and take as given one of its results that the real sin of intellectualism lies precisely in having taken as given the determinate universe of science, that this reproach applies a fortiori to psychological thinking, since it places perceptual consciousness in the midst of a ready made world, and that the attack on the constancy hypothesis carried to its logical conclusion assumes the value of a genuine 'phenomenological reduction'.