Infinite divisibility vs. absolute indivisibility: What separates Einstein and Bergson

Bergson states that motion is “absolutely indivisible”. But motion in physics is standardly taken to be infinitely divisible. Thus, Bergson’s thesis stands in opposition to the manner motion was conceived by Einstein, and also in metaphysical theories such as eternalism, which, since Einstein, is often traced back to special relativity. This paper rejects both positions, and argues that motion is divisible but not infinitely so. The argument is based on an analysis of unified wholes aimed at establishing that they can be comprised of parts (or stages). Motion is such a unified whole. The paper then claims that unified wholes are not part of the vocabulary of physics. This, it is suggested, is the origin of the difference between Einstein’s and Bergson’s conceptions of motion. Bergson’s real objective, it is further argued, was to defend a rich, tensed conception of motion, and it was in this context that he mistakenly stated motion to be indivisible. More generally, Bergson’s theses regarding time and motion are part of his agenda of highlighting the existence and cruciality of knowledge that is extra-scientific and cannot be reduced to science. The paper ends by locating the Einstein–Bergson dispute in the broader context of different philosophical methodologies and conceptions of time, and with a brief discussion of the historical circumstances which, it is suggested, exacerbated the controversy.