アリストテレス『哲学について』(Fr. 16 Ross)における「神」概念
The Concept of Deity in Aristotle's De Philosophia, Fr. 16 Ross
The fragments of Book III of the early dialogue De Philosophia show Aristotle pursuing his studies on Deity and the Universe. Above all, fr. 16, preserved in Simplicius' Commentary in De Caelo 288. 28-289. 15, is characterized by its reference to the philosophical proof of the existence of Deity as well as that of the immutability of Deity. As J. Bernays pointed out, the latter proof presupposes the former. Here, the obvious but unspoken premise of the former proof is clarified, and it is explained in what sense the latter proof presupposes the former.
The discussion of the existence of Deity appears in the first part of the fragment. "In general, where there is a better there is also a best. Since, then, among existing things one is better than another, there is also something that is best, which will be the divine." Most commentators (e. g., W. Jaeger, P. Wilpert, and C. J. De Vogel) have ignored the (obvious to Aristotle, therefore not mentioned) premise of this proof of the existence of Deity as something that is best. Behind this proof lies the premise that a series of better things is not endless : of this Aristotle seems quite convinced. Taking this premise into consideration, we can properly appreciate the validity of the proof of the existence of Deity without the help of the scholastic argumentum ex gradibus, the theory of forms and the realistic scale of entities.
With regard to the proof of the immutability of Deity, the following choices are enumerated and ruled out one by one. The choices are as follows, "Now that which changes is changed either by something else or by itself, and if by something else, either by something better or by something worse, and if by itself, either to something worse or through desire for something nobler." These choices are ruled out on the grounds of the existence of Deity as something that is best, as was argued in the first part of the fragment. The transition of time which change in general presupposes is half hidden in this proof : this presupposition is once taken into account, then left out by means of the nature of "best" that Deity bears. This is the point of this proof which most commentators have not been aware of.
So far as Fr. 16 is concerned, the immutability of Deity can be understood in the same way as in the Corpus. This conclusion raises the questions, "Did Aristotle in the early dialogues have the same opinion on the immutability of Deity as he did in the Corpus ?" and "Is fr. 16 a genuine fragment of De Philosoplzia ?" But we should bear in mind that the fragmentary nature of the dialogue does not permit much speculation on what Aristotle thought Deity to be.