The overwhelming majority of the attempts in exploring the problems related to quantum logical structures and their interpretation have been based on an underlying set-theoretic syntactic language. We propose a transition in the involved syntactic language to tackle these problems from the set-theoretic to the category-theoretic mode, together with a study of the consequent semantic transition in the logical interpretation of quantum event structures. In the present work, this is realized by representing categorically the global structure of a quantum algebra (...) of events (or propositions) in terms of sheaves of local Boolean frames forming Boolean localization functors. The category of sheaves is a topos providing the possibility of applying the powerful logical classification methodology of topos theory with reference to the quantum world. In particular, we show that the topos-theoretic representation scheme of quantum event algebras by means of Boolean localization functors incorporates an object of truth values, which constitutes the appropriate tool for the definition of quantum truth-value assignments to propositions describing the behavior of quantum systems. Effectively, this scheme induces a revised realist account of truth in the quantum domain of discourse. We also include an Appendix, where we compare our topos-theoretic representation scheme of quantum event algebras with other categorial and topos-theoretic approaches. (shrink)

Scientifically speaking, quantum mechanics (QM) is the most successful theory ever made. Philosophically speaking, however, it is the most controversial theory. Its basic principles seem to contravene our deepest intuitions about reality, which are reflected in the metaphysical commitments of classical mechanics (CM). The aim of this paper is twofold. First, I argue that QM implies an ontological challenge, and not merely an “ontic” one, as it has been traditionally interpreted in the analytic tradition. Second, I suggest that positions known (...) as “ontological pluralism” exhibit an internal weakness due to its unwarranted compromise to a representational view of scientific theories. (shrink)

The logic of a physical theory reflects the structure of the propositions referring to the behaviour of a physical system in the domain of the relevant theory. It is argued in relation to classical mechanics that the propositional structure of the theory allows truth-value assignment in conformity with the traditional conception of a correspondence theory of truth. Every proposition in classical mechanics is assigned a definite truth value, either ‘true’ or ‘false’, describing what is actually the case at a certain (...) moment of time. Truth-value assignment in quantum mechanics, however, differs; it is known, by means of a variety of ‘no go’ theorems, that it is not possible to assign definite truth values to all propositions pertaining to a quantum system without generating a Kochen–Specker contradiction. In this respect, the Bub–Clifton ‘uniqueness theorem’ is utilized for arguing that truth-value definiteness is consistently restored with respect to a determinate sublattice of propositions defined by the state of the quantum system concerned and a particular observable to be measured. An account of truth of contextual correspondence is thereby provided that is appropriate to the quantum domain of discourse. The conceptual implications of the resulting account are traced down and analyzed at length. In this light, the traditional conception of correspondence truth may be viewed as a species or as a limit case of the more generic proposed scheme of contextual correspondence when the non-explicit specification of a context of discourse poses no further consequences. (shrink)

ABSTRACT This essay examines error and both external freedom and internal freedom. There is no external freedom (the latitude to choose) without internal freedom (the capacity to choose). Concerning external freedom, it suggests that errors serve as a derivative basis for natural rights. Concerning internal freedom, it overviews four groundbreaking papers from the 1990s by Stephen Boydstun, who suggested that there is no external freedom without internal indeterminism—specifically that associated with quantum probabilities related to neuronal control processes. Also reviewed is (...) work by Elio Conte and by Andrei Khrennikov. Experiments involving a quantum-like model of cognition are discussed. (shrink)

The semantics underlying the propositional structure of Hilbert space quantum mechanics involves an inherent ambiguity concerning the impossibility of assigning definite truth values to all propositions pertaining to a quantum system without generating a Kochen-Specker contradiction. Although the preceding Kochen-Specker result forbids a global, absolute assignment of truth values to quantum mechanical propositions, it does not exclude ones that are contextual. In this respect, the Bub-Clifton “uniqueness theorem” is utilized for arguing that truth-value definiteness is consistently restored with respect to (...) a determinate sublattice of propositions defined by the state of the quantum system concerned and a suitable “preferred” observable. It is suggested that the most natural choice of the latter, especially for confronting the problem of truth valuation in quantum mechanics, results in the determinateness of the observable to be measured. An account of truth of contextual correspondence is thereby provided that is appropriate to the quantum domain of discourse. The resulting account of truth is compatible with a realist conception of truth. Such an account essentially denies that there can be a universal context of reference or an Archimedean standpoint from which to evaluate logically the totality of facts of nature. (shrink)

In this paper we attempt to analyze the physical and philosophical meaning of quantum contextuality. In the first part we will argue that a general confusion within the literature comes from the improper "scrambling" of two different meanings of quantum contextuality. The first one is related to an epistemic interpretation of contextuality, introduced by Bohr, which stresses the incompatibility of quantum measurements. The second, is related to an ontic notion of contextuality, exposed through the Kochen-Specker theorem, which focuses on the (...) constraints to discuss about actual properties within the orthodox formalism of QM. We will show how these two notions have been scrambled together creating an "omelette of contextuality" which has been fully widespread through a popularized "epistemic explanation" of the KS theorem according to which: The outcome of the observable A when mea- sured together with B or together with C will necessarily differ in case [A,B] = [A,C] = 0, and [B,C] ̸= 0. We will show why this statement is not only improperly scrambling epistemic and ontic perspectives, but is also physically and philosophically meaningless. In the second part of the paper, we will analyse the relation between ‘classical contexts’ and QM. We will show that three accepted presuppositions found within the orthodox literature are, in general, false. Namely: that quantum contextuality does not preclude an objective description of physical reality, that the choice of a context restores a classical description of reality, and that the choice of a context is a necessary condition for accounting for empirical statements in QM. (shrink)

The category-theoretic representation of quantum event structures provides a canonical setting for confronting the fundamental problem of truth valuation in quantum mechanics as exemplified, in particular, by Kochen–Specker’s theorem. In the present study, this is realized on the basis of the existence of a categorical adjunction between the category of sheaves of variable local Boolean frames, constituting a topos, and the category of quantum event algebras. We show explicitly that the latter category is equipped with an object of truth values, (...) or classifying object, which constitutes the appropriate tool for assigning truth values to propositions describing the behavior of quantum systems. Effectively, this category-theoretic representation scheme circumvents consistently the semantic ambiguity with respect to truth valuation that is inherent in conventional quantum mechanics by inducing an objective contextual account of truth in the quantum domain of discourse. The philosophical implications of the resulting account are analyzed. We argue that it subscribes neither to a pragmatic instrumental nor to a relative notion of truth. Such an account essentially denies that there can be a universal context of reference or an Archimedean standpoint from which to evaluate logically the totality of facts of nature. (shrink)