428 PHILOSOPHICAL PERIODICALS. scientinque ') agrees with Ostwald in holding that a causal hypothesis is never proved in the proper sense of the word. Such an hypothesis is neither true nor false. It is simply good or bad, useful or harmful, according to circumstances. St. Thomas would seem to have been of this opinion, for in the commentary on Aristotle's treatise De Caelo et Mundo he says : " The suppositions of astronomers are not necessarily- true. Nor are they to be regarded as necessarily true even when they explain the facts of observation, for it may very well be that at some future time an explanation equally satisfactory, though as yet quite un- discovered, may present itself ". G. de Craene ( ' La Connaissance de 1'esprit ') maintains that though, by means of that faculty of abstraction which enables us to apprehend the essence or nature of bodies apart from the notes which characterise it in individual bodies, we may, up to a certain point, place ourselves in relation with things immaterial, never- theless it remains always true that material things constitute the proper object of human thought. From this it follows that our idea of spirit or immaterial substance is a purely negative idea. N. Kaufmann (' La Finalite dans 1'Ordre moral '), following Aristotle and St. Thomas, argues (1) that the perfection of the rational nature of man is the immanent end of moral activity ; (2) that the rational nature of man is the norm and law of moral activity. Reason recognises the nature of man in all its relations, and, when it is sound (Xoyo? ijp&m), it decides rightly as to what is in harmony with that nature, and thus constitutes the norm of conduct; (3) that the rational nature of man is the basis of virtue, and, since it tends towards its own perfection as its end, the principle of finality. No. '24. P. de Munnynck (' L'Hypothese scientitique,' suite et fin) who, in a previous number of the Revue, had contended that hypotheses are not true in the proper sense of the word, inasmuch as they have no rigorously logical connexion with fact, now upholds the usefulness of these hypotheses. From the psychological standpoint, their usefulness is great since they gratify the natural instinct of the reason to seek for causes, an instinct which had been artificially repressed during the processes of mere observation. But, besides this subjective, they have also, as is obvious, an objective value, seeing that they contribute largely to the progressive conquest of the secrets of nature. For their objective usefulness it is necessary however that they should be simple, representative, i.e., that they should appeal to the imagination, comprehensive and free from opposition to any established fact. N. Kaufmann ('La Fiualiti' dans 1'Ordre moral') continuing his studies of finality in the moral order, as set forth in the writings of Aristotle and St. Thomas, maintains that in the moral perfection of human nature there are three degrees, and, corresponding with these three degrees, three tendencies of human nature. (1) The individual man possesses, by virtue of his nature, a certain fundamental perfection which nature strongly urges him to preserve and develop. But (2) man in isolation cannot fully realise the imperative necessities of his nature. He needs for their fulfilment the aid of human society by means of family ties, association with those of his kind, and relation to the State which is the most perfect of societies. To this need corresponds the social tendency. But (3) the greatest perfection of man's is the beatitude which results from union with God. and to this alone man's nature tends not as to a means, but as to its ultimate end. D. Mercier (' La Notion de la Vuriti' ') accepts the traditional definition of logical truth, ri:., the " agreement of thought with reality " but insists that " thought " in this connexion primarily stands for judgment, while "reality" primarily stands for the objective identity of the two terms of the judgment, ;md