254 CRITICAL NOTICES : to deal with his criticism of those two great props of the mechani- cal philosophy, the doctrine of Evolution and the hypothesis of Psychophysical Parallelism. There is the less need for me to speak of the former that Mr. Spencer may almost be cited himself as confitens reus. When a philosopher whose system has been exposed to so damaging an attack on its characteristic principles and method can find no better retort than a complaint against the unauthorised use of capital letters in quotation from his works, one may fairly say that the game is up. In justice to Mr. Spen- cer however it must be said that Prof. Ward's pleasantries at his expense are often heavy as well as pugnacious, and that the real force of his indictment against the Synthetic Philosophy would be more evident if he had abstained more from indulging a tendency to banter. How damaging the indictment is will readily be per- ceived by any one who will read carefully the extraordinary "proof" given in "First Principles" of the doctrine that an absolutely homogeneous physical universe must, in virtue of its homogeneity, burst out into a multitude of local differential move- ments, and then compare Mr. Spencer's text with Prof. Ward's incisive but well-deserved comments. When we reach the discussion of the favourite doctrine of " Parallelism " with which Prof. Ward's second volume opens, we find ourselves passing at last from criticism of the methods and assumptions of natural science to epistemology. Hence it is natu- ral that the author's special views on the metaphysical problems connected with the notions of "causality," "activity," "deter- mination " and " freedom " should make themselves specially felt in this part of his work. It is on these points rather than on the minor details of the argumentation in volume L, that some students whose general sympathy is with the attack on Naturalism will feel bound to part company with the Professor. In the argument by which he shows the. methodological absurdity of the doctrine of two parallel but independent series there is, indeed, little from which any Idealist would care to dissent. In fact, when once the mind has been disabused of the fancy that "science" has somehow proved from the doctrine of " Conservation " the impos- sibility of a mental state influencing the physical series, there seems to be no further intelligible reason for maintaining a doc- trine which cannot even be formulated without contradiction. It might, however, have been well to recognise the practical con- venience of using the concept of "parallelism" as a working hypothesis for purposes of psychophysical investigation. Absurd 'as the doctrine is when put forth as the final truth about the relation of mind to body, it is still practically convenient, as far as possible, to go in psychophysics on the principle of looking for the antecedents of nervous changes in nervous changes and for those of mental changes in mental changes. Of course, like all "work- ing hypotheses," this hypothesis cannot be carried out without a certain amount of conscious fiction. We may, for instance, find