Hilbert Space Quantum Mechanics is Contextual (Reply to R. B. Griffiths)

CHRISTIAN DE RONDE

CADERNOS DE HISTORIA E FILOSOFIA DAS CIENCIAS

UNICAMP

Año: 2016 vol. 2 p. 131 - 160

0101-3424

In a recent paper Robert Griffiths [13] has argued, based on the consistent histories inter- pretation, that Hilbert space quantum mechanics (QM) is non-contextual. According to Griffiths, the problem of contextuality disappears if the apparatus is "designed and operated by a competent experimentalist" and we accept the Single Framework Rule (SFR). In the present paper we will argue that Griffiths? conclusion is untenable. Firstly, we will argue that Kochen-Specker (KS) type contextuality has nothing to do with the measurement pro- cesses nor the measurement problem --solving this problem does not necessarily remove contextuality. Secondly, that the consideration of counterfactual situations is endemic when reasoning by means of physics. Griffiths? SFR amounts to an unprincipled (or impractical) denial of this fact. Thirdly, that Griffiths´ demonstration implies, as a direct consequence, that QM allows a Global Valuation for all properties independently of the context. This would mean, not only that KS theorem is false, but also that the SFR is completely unnec- essary. Finally, we will argue that quantum contextuality should be reconsidered --instead as a problem that we need to escape-- as a main feature of the formalism which must be positively taken into account in order to provide a coherent representation of physical reality and explain what is QM talking about.