Wim Christiaens

After presenting Apostel’s views on scientific realism, I present definitions of the concepts of ontology and metaphysics. I then proceed to develop Apostel’s basic ontology and his metaphysics. Apostel proposed a particular understanding of existence based on his views on causation. He also developed a view of the universe as a causal self-explaining system. I discuss and illustrate three kinds of what he calls “metaphysical deductions” that aim to deliver such a view of the universe. The most important one is the Leibnizian variational method, that should allow us to deduce the existing universe as the ‘best’ of all possible worlds.

As part of the creation-discovery interpretation of quantum mechanics Diederik Aerts presented a setting with macroscopical coincidence experiments designed to exhibit significant conceptual analogies between portions of stuff and quantum compound entities in a singlet state in Einstein—Podolsky—Rosen/Bell-experiments (EPR-experiments). One important claim of the creation-discovery view is that the singlet state describes an entity that does not have a definite position in space and thus does not exist in space. Free Process Theory is a recent proposal by Johanna Seibt of an integrated ontology, i.e., of an ontology suitable for the interpretation of theories of the macrophysical and microphysical domain (quantum field theory). The framework of free process theory allows us to show systematically the relevant analogies and disanalogies between Aerts' experiment and EPR-experiments. From free process ontology it also follows quite naturally that the quantum compound entity described by the singlet state does not exist in space.

The condition of explicit theoretically discursive cognitive performance, as it culminates in scientific activity, is, I claim, the life world. I contrast life world and scientific world and argue that the latter arises from the first and that contrary to the prevailing views the scientific world (actually, worlds, since the classical world is substantially different from the quantum world) finds its completion in the life world and not the other way around. In other words: the closure we used to search in a complete and comprehensive scientific description of all aspects of experience by referring it back to underlying atoms, genes and other scientific objects and the covering laws ruling them, should be sought in a reintegrating and occasionally dissolving of the abstract scientific model in the self-organizational fluidity and superposition-like indeterminateness and non-locality of the life world: “We have to acknowledge the indeterminate as a positive phenomenon” (Merleau-Ponty in his The Phenomenology of Perception).

A worldview has six components. We concentrate on the first two: the descriptive world model and the explanatory world model. In the first half of the paper we make some general remarks on the methodology of world construction. In the second part, we discuss inconsistencies in world models. Adding new fragments to our world model can lead to inconsistencies. Three strategies are distinguished: (i) a partial return to instrumentalism, (ii) paraconsistency, and (iii) the adaptive option. The latter option is elaborated by means of several historical examples and by means of the EPR paradox.

En este artículo, analizamos el significado de las matrices densidad en el formalismo de la mecánica cuántica. Discutimos el problema de los "sistemas cuánticos compuestos" en la lógica cuántica así como también la interpretación de las mezclas impropias. Tomando en cuenta el desarrollo de la lógica cuántica convexa, presentamos un análisis de la estructura formal de la teoría que, argumentaremos, debe ser considerado a la hora de desarrollar un nuevo esquema conceptual para la interpretación de las mezclas cuánticas. In this article, we analyze the meaning of density matrices within the formalism of quantum mechanics. We discuss the problem of compound systems in the context of quantum logic as well as the interpretation of improper mixtures. Taking into account the development of convex quantum logic, we present an analysis of the formal structure of the theory which we will argue, must be taken into account when developing a new conceptual scheme for the interpretation of quantum mixtures