Philosophy of Physics Seminar (Thursday - Week 6, TT25)

Abstract: The advent and rapid growth of quantum information theory and quantum computing has given rise to various radical philosophical theses—most notably John Archibald Wheeler’s claim that physical reality derives from detector-elicited answers to binary yes-or-no questions, famously summarised in his aphorism “it from bit”. Though popular in the physics community, Wheeler’s adage remains ambiguous and under-scrutinised. And where it is examined it is often read literally and dismissed as incoherent or as a form of Berkeleyan idealism. In this paper I propose an alternative interpretation along transcendental lines—or, more specifically, along the lines of Ernst Cassirer’s critical idealism. On this interpretation, the phrase does not express a metaphysical thesis. It does not claim that physical reality is (or is derived from) information. Rather, it claims merely that the objects of scientific cognition (in this case, the objects of quantum information theory) conform to the forms of such cognition. Every object of scientific experience (every “it”), on this view, is conceptually structured—and this because even the elementary act of measurement is itself conceptually structured. Thus, the results of quantum information theory are shaped by information-theoretic concepts (“bits”). By engaging with the work of a neglected figure in the philosophy of physics, I argue that we can extend to Wheeler a greater degree of interpretative charity while also extracting the deepest and most defensible insight from his remarks