120 NEW BOOKS. prehension of onlookers. These depend partly upon their training in judgment, relatively to the particular class of events. We may be con- scious of what kind of event is passing, without being conscious of the details in which it differs from other classes of events, and on which our recognition must be founded ; accordingly Dr. Moller assumes an " unconscious process of comparison of the present with past similar experiences" i.e., unconscious judgments. Rather we should say the decision occurs on the ground of previous judgments, by which a mental disposition has been established : the new impression calls the disposition into play, and the 'Auffitssung' takes place, the subject being uncon- scious only of its conditions in the past, not of any mental factors actually present at the moment. J. L. McIxTYRE. Uber Irikalt und GeUung des Kausalgesetzes. Von Benno Erdmann. Halle : Max Niemeyer, 1905. Pp. 52. This paper, which was read before the section for Methodology of Science at the International Congress of Arts and Sciences, St. Louis, 1904, and an English translation of which is appearing in the forthcoming number of the Philosophical Review, is an interesting attempt to find a via media between the conflicting accounts of Empiricism and Rationalism. After a lucid statement of the psychological facts of the apprehension of succession and of ' uniformity ' in succession, Prof. Erdmann tries to show that consistent Empiricism is bound to reduce causality to mere regular temporal succession. We observe certain uniform sequences in the stream of events, and beyond these uniformities we have no right to go. Indeed, Ernst Mach (' the most consistent modern Empiricist in Germany ') is quoted as holding that the very terms ' cause ' and ' effect ' with their suggestion of a productive activity on the part of the cause suggest ' fetichism,' and that a purely temporal relation must not be interpreted dynamically. If this conclusion holds good, then, as Prof. Erdmann rightly perceives, the element of necessity on which Rationalists have always insisted, is wholly banished from causal connexions. Hence Prof. Erdmann makes an attempt to re-establish it by arguing that the necessity, in causal connexions is the same in principle as the necessity underlying even the simplest judgment of perception. If, e.g., we see a green expanse we are, under pain of self-contradiction, compelled to judge that the expanse is green. In that consists the 'necessity' of the judgment. Similarly, since experience presents us with the fact of uni- formity, we are compelled, if we would avoid contradicting that fact, to judge that causal connexions are necessary. For uniformity, fully thought out, implies necessity, since if there were no necessity the world would be mere irregular chaos, and the conception of chaos is self -contradictory (chaos = a whole without relations). However, though the necessity of causal connexions is thus vindicated against the Empiri- cists, little has been gained, for the Empiricists are right in maintaining the hypothetical character of all causal connexions, so far as we build on them anticipations of the future. We know that a given cause makes a certain effect necessary we do not know whether in future experience we shall meet with that cause again. Every causal law, therefore, on analysis reveals two elements of different value : (1) An element of thought-necessity, according to which like causes necessarily lead to like effects. This is the general and abstract law of causality. (2) An element of hypothesis, viz., the assumption that in future experience we shall meet with the same causes (and, therefore, with the same effects) with which we have been familiar in the past.
