Andreas Bartels

Dieses Lehrbuch behandelt zentrale naturphilosophische Probleme, die durch Theorien der modernen Naturwissenschaften aufgeworfen werden. Es fragt, welches Bild von Raum, Zeit, Materie, Leben und Bewusstsein sich aus ihnen ergibt, aber auch nach den Konsequenzen der aktuellen Umweltkrise für unser praktisches Verhältnis zur Natur. Der Autor Prof. em. Dr. Andreas Bartels hat Mathematik, Physik und Philosophie studiert und ist emeritierter Professor für Natur- und Wissenschaftsphilosophie an der Universität Bonn.

The recent work of Paul Teller and Sunny Auyang in the philosophy of Quantum Field Theory (QFT) has stimulated the search for the fundamental entities in this theory. In QFT, the classical notion of a particle collapses. The theory does not only exclude classical, i.e., spatiotemporally identifiable particles, but it makes particles of the same type conceptually indistinguishable. Teller and Auyang have proposed competing ersatz-ontologies to account for the 'loss of particles': field quanta vs. field events. Both ontologies, however, suffer from serious defects. While quanta lack numerical identity, spatiotemporal localizability, and independence of basis-representations, events--if understood as concrete measurement events--are related to the theory only statistically. I propose an alternative solution: The entities of QFT are events of the type 'Quantum system, S, is in quantum state, Ψ '. These are not point events, but Davidsonian events, i.e., they can be identified by their location within the causal net of the world

Nikos K. Logothetis University of Manchester, Manchester, UK In binocular rivalry, the visual percept alternates stochastically between two dichoptically presented stimuli. It is established that both processes related to the eye of origin and binocular, stimulus-related processes account for these fluctuations in conscious perception. Here we studied how their relative contributions vary over time. We applied brief disruptions to rivalry displays, concurrent with an optional eye swap, at varying time intervals after one stimulus became visible (dominant). We found that early in a dominance phase the dominant eye determined the percept by stabilizing its own contribution (regardless of the stimulus), with an additional yet weaker stabilizing contribution of the stimulus (regardless of the eye). Their stabilizing contributions declined in parallel with time so that late in a dominance phase the stimulus (and in some cases also the eye-based) contribution turned negative, favoring a perceptual (or ocular) switch. Our findings show that depending on the time, first processes related to the eye of origin and then those related to the stimulus can have a greater net influence on the stability of the conscious percept. Their co-varying change may be due to feedback from image- to eyeof-origin representations.

The aim of this paper is to defend the structural concept of representation, as defined by homomorphisms, against its main objections, namely: logical objections, the objection from misrepresentation, theobjection from failing necessity, and the copy theory objection. The logical objections can be met by reserving the relation ‘to be homomorphic to’ for the explication of potential representation (or, of the representational content). Actual reference objects (‘targets’) of representations are determined by (intentional or causal) representational mechanisms. Appealing to the independence of the dimensions of ‘content’ and ‘target’ also helps to see how the structural concept can cope with misrepresentation. Finally, I argue that homomorphic representations are not necessarily ‘copies’ of their representanda, and thus can convey scientific insight.

The concept of cognition has undergone considerable extension, first, by intensive empirical study of representational systems and their role for the possession and application of cognitive capacities and second, by the turn to practical knowledge. By these two developments, the field of research on cognition has been opening with respect to which all eager attempts of demarcation between the humanities and the sciences seem to be outdated. This brings about institutional changes in the scientific landscape as can be seen in the current tendency to find interdisciplinary centres for the investigation of cognitive phenomena all over the world.

The rationality of scientific concept formation in theory transitions, challenged by the thesis of semantic incommensurability, can be restored by theChains of Meaning approach to concept formation. According to this approach, concepts of different, succeeding theories may be identified with respect to referential meaning, in spite of grave diversity of the mathematical structures characterizing them in their respective theories. The criterion of referential identity for concepts is that they meet a relation ofsemantic embedding, i.e. that the embedding concept can be substituted by the embedded one in classical limit situations. Three case studies from contemporary physics theories will be used to show that the Chains of Meaning approach not only yields meaning comparisons for already established concepts (as for Newtonian and Schwarzschild mass) but is also well suited to characterize actual scientific strategies of concept formation in yet open cases such as black hole entropy or relativistic thermodynamics.