in the narrower sense of the word, no other problems than such as are treated by the critical science of knowledge." Philosophy is the self-knowledge of science. This standpoint will, no doubt, be a sufficient condemnation of the whole work in the eyes of those to whom the very name Erkenntnisstheorie is an abomination; but when we find that Professor Riehl's definition of the task of Erkenntnisstheorie[1] coincides exactly with T. H. Green's definition of the problem of metaphysic,[2] we may conclude that, whatever be the difference in result, the methods of these German and English Kantians are the same. Indeed, the parallel might be easily extended, for the criticism in the case of each of these authors is directed largely against the naïve or dogmatic assumptions of a metaphysical natural science. The distinguishing feature of Professor Riehl's book, and that which in my opinion gives it especial value for English readers, is that the author is in close touch with the science of to-day, and writes rather as a critic within science than as a critic upon science. The average scientific worker, in America at least, is usually quite innocent of any philosophy except the defunct and forgotten theories of his college days,—and the system of Mr. Spencer. He reads the latter because it offers a synthesis of present scientific conceptions; and while it cannot be said that Professor Riehl's book offers no difficulties to the reader not thoroughly grounded in Kantian criticism, it is, I think, more likely than any work of similar aim to appeal to the scientist who reflects on the broader aspects of his work. Nor does this mean that the work is any the less valuable to the student of philosophy because of its scientific basis. A metaphysics which has 'got beyond' the need of such careful and detailed criticism of modern scientific concepts and methods, is an object of natural suspicion. If we are to make real progress in our views of reality, the most promising, if not the only safe, starting-point is to be found in the methods and concepts by which modern thought is mastering its problems one by one, interpreting its environment, and so coming to a consciousness of itself; and I for one cannot think that this work of criticism has been so thoroughly done in English philosophy that Professor Riehl's study will not be a valuable help.
The author's attitude toward metaphysics might be easily misunderstood from the statement quoted above, which denies the possibility of such a science. It is, however, against a metaphysics which would dispense with criticism that the spirit of his polemic is really directed. For while, in the chapter on "Metaphysical
