In an illusion, if what has been said in the earlier part of this section is right, the essential thing is the presence to the mind of some false proposition, which may be affirmed or denied according as we are or are not deceived. But what precisely is this false proposition in each case? And, a second question, on what grounds do we entertain it?

The following discussion arises out of reflection upon a number of related topics. One of these is the problem of perception, and in particular of perceptual illusion. Another is the use which has been made, e.g. by Bradley, of the distinction between appearance and reality as a guiding principle of metaphysical inquiry. But the immediate occasion of the present inquiry is the attempt to discover what Kant in particular has to say upon these and similar problems. It is for this (...) reason that I have given the paper its title, and not because I wish to pose as an expert in Kantian scholarship. What contribution I can make to Kantian studies is only that of the outsider whose questions may perhaps suggest to the experts lines of inquiry which their very familiarity with Kant's ways of expressing himself may have led them to overlook. But the aim of the paper is not so much to discover what Kant meant as to formulate a particular view which may have been Kant's in such a way that we can judge whether it is true or not. The decision on that point, however, falls outside the scope of the present discussion. (shrink)