For many scientific research topics it is important to clarify which elements of reality are referred to by particular descriptions. In order to avoid category mistakes and false conclusions it is essential to distinguish carefully between ontic and epistemic descriptions. Ontic descriptions of a system refer to its states and properties independent of observations. By contrast, epistemic descriptions are always relative to the context of observation.

The distinction of ontic and epistemic descriptions was paradigmatically and in detail worked out for the formalism of quantum theory, where this is possible in a particularly transparent fashion. The discussion of cognitive systems is prone for similar problems, as was recently demonstrated impressively by Walde.

Reductionist approaches in debates about consciousness assume that mental states can more or less be reduced to brain states. By contrast, emergentist conceptions ascribe an irreducibility to mental states, which is graded depending on the type of emergence concept under consideration. We proposed a version of contextual emergence which is characterized by the idea that brain states provide necessary, but not sufficient conditions for mental states.

We demonstrated that contextual emergence provides a correct and detailed description of particular properties of physical systems. The construction of emergent properties in this sense follows basic principles, due to which contingent contexts at a higher level of description are implemented by stability criteria at the lower level. We employed this procedure successfully for the discussion of mental and neural states.

Motivated by the recent completion of Wolfgang Pauli's scientific correspondence, we reviewed Pauli's ideas concerning the psychophysical problem and placed them in the context of current debate. In detail these ideas are: non-Boolean descriptions in science, Pauli's conceptions of creative work, speculations inspired by Jung about a symmetry breaking of a psychophysically neutral reality and its relationship to notions of time. Finally, Pauli's criticism of the then predominant neo-Darwinian ideas about biological evolution are to be mentioned, which have received important modifications today.