Kim Boström

Im Jahre 1998 verblüfften Andy Clark und David Chalmers die philosophische Gemeinschaft mit der so genannten These des erweiterten Geistes, die im Kern besagt, dass kognitive Systeme nicht-biologische Komponenten enthalten können und sich damit über die Grenzen biologischer Organismen hinaus erstrecken können. Die These wird seitdem nicht nur von Philosophen, sondern auch von Kognitions- und Neurowissenschaftlern intensiv und kontrovers diskutiert. In den Beiträgen, die in dem vorliegenden ersten deutschsprachigen Band zur These des erweiterten Geistes versammelt sind, werden u.a. die folgenden Fragen behandelt: Was soll es heißen, dass der Geist nicht (nur) im Kopf ist? In welchem Sinne könnte er erweitert sein, und welche Möglichkeiten der Erweiterung gibt es? Welche Zusammenhänge bestehen zwischen Geist und Kognition sowie zwischen Kopplung und Konstitution? Was genau besagt der von Clark und Chalmers vorgebrachte aktive Externalismus? Welche Bedeutung hat die These des erweiterten Geistes für repräsentationalistische und für funktionalistische Theorien des Geistes sowie für Theorien kollektiver Intentionalität und sozialer Kognition? Welche Anwendungen der These könnte es geben?

Postural reflexes are essential for locomotion and postural stability, and may play an important role in the etiology of chronic back pain. It has recently been theoretically predicted, and with the help of unilateral perturbations of the trunk experimentally confirmed that the sensorimotor control must lower the reflex amplitude for increasing reflex delays to maintain spinal stability. The underlying neuromuscular mechanism for the compensation of postural perturbations, however, is not yet fully understood. In this study, we applied unilateral and bilateral sudden external perturbations to the trunk of healthy subjects and measured the muscular activity and the movement onset of the trunk. We found that the onset of the trunk muscle activity is prior to, or coincident with, the onset of the trunk movement. Additionally, the results of our experiments imply that the muscular response mechanism integrates distant sensory information from both sides of the body. These findings rule out a simple monosynaptic stretch reflex in favor of a more complex polysynaptic postural reflex mechanism to compensate postural perturbations. Moreover, the previously predicted negative correlation between reflex delay and reflex gain was also confirmed for bilateral perturbations.

A non-relativistic quantum mechanical theory is proposed that describes the universe as a continuum of worlds whose mutual interference gives rise to quantum phenomena. A logical framework is introduced to properly deal with propositions about objects in a multiplicity of worlds. In this logical framework, the continuum of worlds is treated in analogy to the continuum of time points; both “time” and “world” are considered as mutually independent modes of existence. The theory combines elements of Bohmian mechanics and of Everett’s many-worlds interpretation; it has a clear ontology and a set of precisely defined postulates from where the predictions of standard quantum mechanics can be derived. Probability as given by the Born rule emerges as a consequence of insufficient knowledge of observers about which world it is that they live in. The theory describes a continuum of worlds rather than a single world or a discrete set of worlds, so it is similar in spirit to many-worlds interpretations based on Everett’s approach, without being actually reducible to these. In particular, there is no splitting of worlds, which is a typical feature of Everett-type theories. Altogether, the theory explains (1) the subjective occurrence of probabilities, (2) their quantitative value as given by the Born rule, and (3) the apparently random “collapse of the wavefunction” caused by the measurement, while still being an objectively deterministic theory.