Page:Mind (New Series) Volume 9.djvu/135

NEW BOOKS. 121 on Geometry are a farrago of logical fallacies, historical blunders, and mathi itir;il errors, culminating in a pretended proof of the axiom of parallels. The discussion of Mechanics is mainly directed against Mach, and insists on the necessity of absolute motion, which the author, like Leibniz, deduces by means of causality. He fails, however, to under- stand the consequences of absolute motion, since he asserts, contrary to received Dynamics, that two particles alone in the world would have to move in the straight line joining them. Atomism is regarded as a priori necessary, and action at a distance as unavoidable, though the latter, it is confessed, cannot be anthropomorphised. Vortex atoms are dismissed with the single remark that they are the maddest imagina- tion since the time of the Vedas (p. 104), and no arguments are to be found against a plenum. The law of inertia is deduced from the prin- ciple that every change is to have a cause ; with Heymans, experience is allowed to decide whether the principle is to apply to change of place or change of velocity. It is not realised that both, if the principle be sound, require causes, and that, if one may be uncaused, so may the other. The book, though it has some good sections, shows, despite violent partisanship, an almost total lack of real argument on controverted points. It also illustrates the fact that philosophers subsequent to Kant, in writing on mathematics, have thought it unnecessary to become acquainted with the subjects they were discussing, and have therefore left to the painful and often crude efforts of mathematicians every genuine advance in mathematical philosophy. B. EUSSELL. Die Moderne Pliysiologische Psychologic in Deutschland. E-ine historisch- Imtische Untersuchung mit besonderer Berucksichtigung de.s Problems der Aufmerksamkeit. Von W. HEINRICH. Zweite teilweise umgear- beitete und vergrbsserte Ausgabe. Zurich : E. Speidel, 1899 ; Lon- don : Williams & Norgate. Pp. viii., 249. Price 4s. net. Zur Prinzipienfrage der Psychologic. Von W. HEINRICH. Zurich : E. Speidel, 1899 ; London : Williams & Norgate. Pp. vi., 74. Price 2s. net. Heinrich's position, as developed in his Prinzipienfrage, may be summed up as follows. For scientific purposes we must regard the world as a manifold whose parts are qualitatively differentiated. A naive realism is the only justifiable presupposition. Hence we must exclude from our point of view derived notions such as those of mass, energy and con- sciousness. All there is to consider (here, as in other places, Heinrich closely follows Avenarius) is the individual, his fellow-men and their utterances, and his complex environment. The strictly scientific method is descriptive, and never goes behind the facts for an explanation. Psy- chology, accordingly, does not aim at deciphering man's consciousness. Its special task is to investigate the attitude of the individual in relation to his fellow-men and to his environment. With this end in view it takes cognisance only of the interaction between the individual, physio- logically considered, and his environment ; and that because hi the ob- jective world alone can the law of causation be rigidly and usefully applied. Hence those theories which imply an introspective basis, or introduce a subjective factor, should be dismissed as weak, if not as self- contradictory. Between the individual and the environment we must assume the existence of a complete chain of physical sequence, unin- terrupted by any psychic links. Many of Heinrich's arguments in