Online research in philosophy

In our everyday discourse, we distinguish without fail between minds and bodies or between the mental and the physical. Yet, in philosophy there is a tendency to get rid of this divide. Roughly, the naturalist wants to reduce or to identify the mental with the physical in order to provide a unified basis for scientific research. The idealist, in contrast, sticks to the mental as a precondition of grasping the physical. The physical then tends to turn into mere mental representations. These attempts to overcome the divide, however, are not very promising. While the first tries to assimilate the mental to the physical, the second takes the opposite approach with the result that either the mental or the physical goes by the board. Fortunately, there is a third option: the realist maintains that the mental exists along with the physical.

This article defends a modest version of the Physical Church-Turing thesis (CT). Following an established recent trend, I distinguish between what I call Mathematical CT—the thesis supported by the original arguments for CT— and Physical CT. I then distinguish between bold formulations of Physical CT, according to which any physical process—anything doable by a physical system—is computable by a Turing machine, and modest formulations, according to which any function that is computable by a physical system is computable by a Turing machine. I argue that Bold Physical CT is not relevant to the epistemological concerns that motivate CT and hence not suitable as a physical analog of Mathematical CT. The correct physical analog of Mathematical CT is Modest Physical CT. I propose to explicate the notion of physical computability in terms of a usability constraint, according to which for a process to count as relevant to Physical CT, it must be usable by a finite observer to obtain the desired values of a function. Finally, I suggest that proposed counterexamples to Physical CT are still far from falsifying it because they have not been shown to satisfy the usability constraint.

We can find no place in psychology for the concept of stimulus as a physical agent to which an individual responds in a psychological manner. Moreover, we can find no place for sensation and image when considered as simple mental elements. We would also purge ...

Relational quantum mechanics is an interpretation of quantum theory which discards the notions of absolute state of a system, absolute value of its physical quantities, or absolute event. The theory describes only the way systems affect each other in the course of physical interactions. State and physical quantities refer always to the interaction, or the relation, between two systems. Nevertheless, the theory is assumed to be complete. The physical content of quantum theory is understood as expressing the net of relations connecting all different physical systems.

Some features of physical science relevant for a discussion of physical explanation are mentioned. The D-N account of physical explanation is discussed, and it is seen to restrict the scope of explanation in physical science because it imposes the requirement that the explanandum must be deducible from the explanans. Analysis shows that an alternative view of scientific explanation, called the instance view, allows a wider range of physical explanations. The view is seen to be free from a certain class of counter examples to the D-N theory.

With reference to two specific modalities of sensation, the taste of saltiness of chloride salts, and the loudness of steady tones, it is shown that the laws of sensation (logarithmic and power laws) are expressions of the entropy per mole of the stimulus. That is, the laws of sensation are linear functions of molar entropy. In partial verification of this hypothesis, we are able to derive an approximate value for the gas constant, a fundamental physical constant, directly from psychophysical measurements. The significance of our observation lies in the linking of the phenomenon of “sensation” directly to a physical measure. It suggests that if the laws of physics are universal, the laws of sensation and perception are similarly universal. It also connects the sensation of a simple, steady physical signal with the molecular structure of the signal: the greater the number of microstates or complexions of the stimulus signal, the greater the magnitude of the sensation (saltiness or loudness). The hypothesis is currently tested on two sensory modalities.

My aim in this paper is to defend a version of the brain process theory, or identity thesis, which differs in one important respect from the theory put forward by J.J.C. Smart. I shall argue that although the sensations which a person experiences are, as a matter of contingent fact, brain processes, nonetheless there are facts about sensations which cannot be described or understood in terms of any physical theory. These 'mental' facts cannot be described by physics for the simple reason that physical descriptions are designed specifically to avoid mentioning such facts. Thus in giving a physical explanation of a sensation we necessarily describe and render intelligible that sensation only as a physical process, and not also as a sensation. If we are to describe and render intelligible a person's sensations, or inner experiences, as sensations, and not as physical processes occurring in that person's brain, then we must employ a kind of description that connot be derived from any set of physical statements.