the appearances it contains, is, together with its determinations, known to us only by
means of experience or perception. I, on the contrary, prove in the first place that space
(and also time, which Berkeley did not consider) and all its a priorideterminations can
be known by us, because, no less than time, it inheres in us as a pure form of our sensi-
bility before all perception or experience and makes all intuition of the form, and there-
fore all appearances, possible. It follows from this that, as truth rests on universal and
necessary laws as its criteria, experience, according to Berkeley, can have no criteria of
truth because its phenomena* (according to him) have nothing a prioriat their founda-
tion, whence it follows that experience is nothing but sheer illusion; whereas with us,
space and time (in conjunction with the pure concept of the understanding) prescribe
their law to all possible experience a prioriand, at the same time, afford the certain
criterion for distinguishing truth from illusion therein.
My so-called (properly critical) idealism is of quite a special character, in that it
subverts the ordinary idealism and in that only through it all a prioriknowledge, even
that of geometry, receives objective reality, which, without my demonstrated ideality of
space and time, could not be maintained by the most zealous realists. This being the
state of the case, I could wish, in order to avoid all misunderstanding, to have named
this conception of mine otherwise, but to alter it altogether is probably impossible.
It may be permitted me however, in future, as has been above intimated, to term it
“formal” or, better still, “critical” idealism, to distinguish it from the dogmatic idealism
of Berkeley and from the skeptical idealism of Descartes.
Beyond this, I find nothing remarkable in the judgment of my book. The reviewer
makes sweeping criticisms, a mode prudently chosen, since it does not betray one’s own
knowledge or ignorance; a single thorough criticism in detail, had it touched the main
question, as is only fair, would have exposed either my error or my reviewer’s measure of
insight into this species of research. It was, moreover, not a badly conceived plan, in order
at once to take from readers (who are accustomed to form their conceptions of books from
newspaper reports) the desire to read the book itself, to pour out in one breath a number of
passages in succession which, torn from their connection with their premises and expla-
nations, must necessarily sound senseless, especially considering how antipathetic they
are to all school-metaphysics; to exhaust the reader’s patience ad nauseam,and then, hav-
ing made me acquainted with the lucid proposition that persistent illusion is truth, to con-
clude with the crude paternal moralization: to what end, then, the quarrel with accepted
language; to what end, and whence, the idealistic distinction? A judgment which seeks all
that is characteristic of my book, first supposed to be metaphysically heterodox, in a mere
innovation of the nomenclature proves clearly that my would-be judge has understood
nothing of the subject and, in addition, has not understood himself.**846 IMMANUELKANT
376
**The reviewer often fights with his own shadow. When I oppose the truth of experience to dream, he
never thinks that I am here speaking simply of the well-known somnio objective sumtoof the Wolffian philoso-
phy, which is merely formal, and with which the distinction between sleeping and waking is in no way concerned—
a distinction which can indeed have no place in a transcendental philosophy. For the rest, he calls my deduction
of the categories and table of the principles of the understanding “common well-known axioms of logic and
ontology, expressed in an idealistic manner.” The reader need only consult these Prolegomenaupon this point to
convince himself that a more miserable and historically incorrect judgment could hardly be made.*Idealism proper always has a mystical tendency, and can have no other, but mine is solely designed
for the purpose of comprehending the possibility of our a prioriknowledge of objects of experience, which is
a problem never hitherto solved or even suggested. In this way all mystical idealism falls to the ground, for
(as may be seen in Plato) it inferred from our cognitions a priori(even from those of geometry) another intu-
ition different from that of the senses (namely, an intellectual intuition), because it never occurred to anyone
that the senses themselves might intuit a priori.375