Françoise Balibar, Professor Emeritus of physics at the Université Denis Diderot, Paris VII gave a wonderful keynote on final day of the Philosophy After Nature conference in Utrecht whose title was drawn from Ernst Mach’s aphorism Die Natur ist nur einmal da (Nature is there only once).
Here she discussed the philosophical implications of failures of univocity or “complete determination” in areas such as space-time physics – points where there seems no way of uniquely individuating objects by all the properties assigned in physical theory. A key example, here, was the Einstein ‘hole argument’ which some take to imply that mathematically distinct models of the same space time built on alternate coordinate assignments are physically equivalent (or, for old-style realists about space-time, that the manifold has additional but observationally inaccessible structure). The upshot was that we can no longer view events as individuated by their relations to an independently subsisting world or subject (to observe events, you must be amid them!). It also induced the intriguing reference to Deleuze’s claim that physical science has no concept of difference.
I haven’t unpacked the implications of her talk by any means but would be delighted to discuss these themes further.
Altogether an inspiring ending to a wonderful conference characterized by some excellent keynotes and panels.