Progress in brain research, especially in the domain of cognitive neuroscience, renders phenomena that have traditionally been subjects of the humanities amenable to scientific investigation. It has now become possible to investigate the neuronal underpinnings of mental phenomena such as perception, decision making, control of attention, language perception and production, action planning, storage and recall of memories, emotions and moods, desires and aversions, and last but not least consciousness. This research agenda is confronted with a number of fascinating challenges. One is the immense complexity of the brain processes that underlie these highly-differentiated cognitive functions. Another results from the fact that many of the phenomena whose neuronal correlates are to be investigated are subjective phenomena, accessible and describable only from a first-person perspective. Hence there is an epistemically problematic gap between what is observable from the third-person perspective of scientific inquiry and the explananda that need to be defined in terms of first-person experience. Yet another challenge is that a relatively young scientific discipline is set to enter territories that for millennia have been ploughed by great minds who have coined terms, formulated concepts, and constructed belief systems based on evidence extracted from introspection, intuition, and observations that relied exclusively on the natural senses. This raises numerous and on occasions frustrating problems for communication, because bridges have yet to be built between the more recent naturalistic description systems and the highly-differentiated terminology nurtured in the humanities. Some of these problems surface in passionate discussions on the existence of free will, the nature of perception, the constitution of the Self, and intentionality and mental causation—and above all on the question of whether it is even possible to identify neuronal correlates of mental, subjective phenomena.
In this chapter some of these challenges will be discussed from a neurobiological perspective. We shall first review the state of the art in the field of cognitive neuroscience, emphasizing recent changes in our views on the brain. These have been forced upon us by the novel data produced by new and powerful technologies. These insights show the brain to be a highly distributed, self-active system with non-linear dynamics; rather than a hierarchically-organized stimulus-response machine, as has been proposed by behaviourist theories. Subsequently, an excursion will be made into epistemology, to establish the extent to which brain research can contribute to philosophical discussions concerning the nature of perception. The process of perceiving will be interpreted as a constructive act in which sparse sensory signals are matched with a huge amount of stored knowledge; and the various sources of this knowledge will be discussed. This section will set the stage for the following discussion of the putative neuronal correlates of consciousness (NCC), as it will highlight the cognitive constraints and idiosyncrasies of cognitive systems that owe their abilities to evolutionary processes. Before reviewing various theories on the NCC, an attempt will be made to define the explanandum—in full awareness of the futility of this attempt. The review of experimental work in search of the NCC will be followed by a brief account of our own experimental contributions, and then an attempt will be made to demystify the so-called “hard problem” of consciousness—the problem of finding a naturalistic explanation for the qualia, namely these immaterial connotations of our experiences. My proposal will be that the problem can be alleviated if we consider not only individual brains and biological evolution but also cultural evolution and the social realities that have emerged from socio-cultural interaction between human beings.
As this contribution addresses an interdisciplinary audience I considered it appropriate to not only refer to published work when alluding to experimental findings and concepts but to sometimes provide explicit and detailed background information. To this end I have adapted passages from a few of my own publications, in which I had addressed some of the issues that needed to be recapitulated for the sake of clarity in the present contribution. These passages include descriptions of experimental findings from my lab and descriptions of the state of the art in the neurosciences.