ar X iv : q ua nt - p h / 05 07 22 0 v 1 22 J ul 2 00 5 When champions meet : Rethinking the Bohr – Einstein debate ∗

Einstein's philosophy of physics (as clarified by Fine and Howard) was predicated on his Trennungsprinzip, a combination of separability and locality, without which he believed " physical thought " and " physical laws " to be impossible. Bohr's philosophy (as elucidated by Hooker, Scheibe, Folse, Howard, and others), on the other hand, was grounded in a seemingly different doctrine about the possibility of objective knowledge, namely the necessity of classical concepts. In fact, it follows from Raggio's Theorem in algebraic quantum theory that within a suitable class of physical theories Einstein's doctrine is mathematically equivalent to Bohr's, so that quantum mechanics accommodates Einstein's Trennungsprinzip if and only if it is interpretedà la Bohr through classical physics. Unfortunately, the protagonists themselves failed to discuss their differences in a constructive way, since in its early phase their debate was blurred by an undue emphasis on the uncertainty relations, whereas in its second stage it was dominated by Einstein's flawed attempts to establish the " incompleteness " of quantum mechanics. These two aspects of their debate may still be understood and appreciated, however, as reflecting a much deeper and insurmountable disagreement between Bohr and Einstein on the knowability of Nature. Using the theological controversy on the knowability of God as a analogy, Einstein was a Spinozist, whereas Bohr could be said to be on the side of Maimonides. Thus Einstein's off-the-cuff characterization of Bohr as a 'Talmudic philosopher' was spot-on.