Patricia Churchland

Anydomainofscientificresearchhasitssustainingorthodoxy. Thatis, research on a problem, whether in astronomy, physics, or biology, is con- ducted against a backdrop of broadly shared assumptions. It is these as- sumptionsthatguideinquiryandprovidethecanonofwhatisreasonable-- of what "makes sense." And it is these shared assumptions that constitute a framework for the interpretation of research results. Research on the problem of how we see is likewise sustained by broadly shared assump- tions, where the current orthodoxy embraces the very general idea that the business of the visual system is to create a detailed replica of the visual world, and that it accomplishes its business via hierarchical organization and by operatingessentiallyindependently of other sensorymodalitiesas well as independently of previous learning, goals, motor planning, and motor execution.

Beginning with Thomas Nagel, various philosophers have propsed setting conscious experience apart from all other problems of the mind as ‘the most difficult problem’. When critically examined, the basis for this proposal reveals itself to be unconvincing and counter-productive. Use of our current ignorance as a premise to determine what we can never discover is one common logical flaw. Use of ‘I-cannot-imagine’ arguments is a related flaw. When not much is known about a domain of phenomena, our inability to imagine a mechanism is a rather uninteresting psychological fact about us, not an interesting metaphysical fact about the world. Rather than worrying too much about the meta-problem of whether or not consciousness is uniquely hard, I propose we get on with the task of seeing how far we get when we address neurobiologically the problems of mental phenomena

As neuroscience uncovers these and other mechanisms regulating choices and social behaviour, we cannot help but wonder whether anyone truly chooses anything (though see "Is the universe deterministic?"). As a result, profound questions about responsibility are inescapable, not just regarding criminal justice, but in the day-to-day business of life. Given that, I suggest that free will, as traditionally understood, needs modification. Because of its importance in society, any description of free will updated to fit what we know about the nervous system must also reflect our social need for a working concept of responsibility.

Within the domain of philosophy, it is not unusual to hear the claim that most questions about the nature of consciousness are essentially and absolutely beyond the scope of science, no matter how science may develop in the twenty-first century. Some things, it is pointed out, we shall never _ever_ understand, and consciousness is one of them (Vendler 1994, Swinburne 1994, McGinn 1989, Nagel 1994, Warner 1994). One line of reasoning assumes that consciousness is the manifestation of a distinctly nonphysical thing, and hence has no physical properties that might be explored by techniques suitable to physical things. Dualism, as this view is known, is still to be found among those within the tradition of Kant and Hegel, as well as among some with religious convictions. Surprisingly, however, strenuous foot-dragging is evident even among philosophers of a materialist conviction. Indeed, one might say that it is the philosophical fashion of the 90's to pronounce consciousness unexplainable, and to find the explanatory aspirations of neurobiology to be faintly comic if not rather pitiful. The very word, "reductionism" has come to be used more or less synonymously with "benighted-scientism-run-amok", where scientistm apparently means "applying scientific techniques to domains where they are inapplicable." McGinn, perhaps the most unblushing of the naysayers, insists that we cannot expect even to make any headway on the problem. (p. 114) Ironically perhaps, here we are at a conference in honor of Dr. Herbert Jasper who was a great pioneer in moving neuroscience forward on this problem, and where results will be presented allegedly _showing_ additional progress on the problem. Because I am quite optimistic about future scientific progress on the nature of consciousness, my aim here, as a philosopher, is to address the most popular and influential of the skeptical arguments, and to explain why I find them unconvincing. Thus the overall form of the paper is negative, in the sense that I want to show why a set of naysaying arguments fail.

We critically review themushrooming literature addressing the neuralmechanisms of moral cognition (NMMC), reachingthe following broad conclusions: (1) researchmainly focuses on three inter-relatedcategories: the moral emotions, moral socialcognition, and abstract moral reasoning. (2)Research varies in terms of whether it deploysecologically valid or experimentallysimplified conceptions of moral cognition. Themore ecologically valid the experimentalregime, the broader the brain areas involved.(3) Much of the research depends on simplifyingassumptions about the domain of moral reasoningthat are motivated by the need to makeexperimental progress. This is a valuablebeginning, but as more is understood about theneural mechanisms of decision-making, morerealistic conceptions will need to replace thesimplified conceptions. (4) The neuralcorrelates of real-life moral cognition areunlikely to consist in anything remotely like a``moral module'' or a ``morality center.'' Moralrepresentations, deliberations and decisionsare probably highly distributed and notconfined to any particular brainsub-system. Discovering the basic neuralprinciples governing planning, judgment anddecision-making will require vastly more basicresearch in neuroscience, but correlatingactivity in certain brain regions withwell-defined psychological conditions helpsguide neural level research. Progress on socialphenomena will also require theoreticalinnovation in understanding the brain'sdistinctly biological form of computationthat is anchored by emotions, needs, drives,and the instinct for survival.

Progress in the neurosciences is profoundly changing our conception of ourselves. Contrary to time-honored intuition, the mind turns out to be a complex of brain functions. And contrary to the wishful thinking of some philosophers, there is no stemming the revolutionary impact that brain research will have on our understanding of how the mind works. Brain-Wise is the sequel to Patricia Smith Churchland's Neurophilosophy, the book that launched a subfield. In a clear, conversational manner, this book examines old questions about the nature of the mind within the new framework of the brain sciences. What, it asks, is the neurobiological basis of consciousness, the self, and free choice? How does the brain learn about the external world and about its own introspective world? What can neurophilosophy tell us about the basis and significance of religious and moral experiences? Drawing on results from research at the neuronal, neurochemical, system, and whole-brain levels, the book gives an up-to-date perspective on the state of neurophilosophy—what we know, what we do not know, and where things may go from here.

Philosophy, in its traditional guise, addresses questions where experimental science has not yet nailed down plausible explanatory theories. Thus, the ancient Greeks pondered the nature of life, the sun, and tides, but also how we learn and make decisions. The history of science can be seen as a gradual process whereby speculative philosophy cedes intellectual space to increasingly wellgrounded experimental disciplines—first astronomy, but followed by physics, chemistry, geology, biology, archaeology, and more recently, ethology, psychology, and neuroscience. Science now encompasses plausible theories in many domains, including large-scale theories about the cosmos, life, matter, and energy. The mind’s turn has now come. The classical ‘‘mind’’ questions center on free will, the self, consciousness, how thoughts can have meaning and ‘‘aboutness,’’ and how we learn and use knowledge. All these matters interlace with questions about morality: where values come from, the roles of reason and emotion in choice, and the wherefore of responsibility and punishment. The vintage mind/body problem is a legacy of Descartes: if the mind is a completely nonphysical substance, as he thought, how can it interact causally with the physical brain? Since the weight of evidence indicates that mental processes actually are processes of the brain, Descartes’ problem has disappeared. The classical mind/ body problem has been replaced with a range of questions: what brain mechanisms explain learning, decision making, self-deception, and so on. The replacement for ‘‘the mind-body problem’’ is not a single problem; it is the vast research program of cognitive neuroscience. The dominant methodology of philosophy of mind and morals in the twentieth..

A remarkable hypothesis has recently been advanced by Libet and promoted by Eccles which claims that there is standardly a backwards referral of conscious experiences in time, and that this constitutes empirical evidence for the failure of identity of brain states and mental states. Libet's neurophysiological data are critically examined and are found insufficient to support the hypothesis. Additionally, it is argued that even if there is a temporal displacement phenomenon to be explained, a neurophysiological explanation is most likely

Explaining the nature and mechanisms of conscious experience in neurobiological terms seems to be an attainable, if yet unattained, goal. Research at many levels is important, including research at the cellular level that explores the role of recurrent pathways between thalamic nuclei and the cortex, and research that explores consciousness from the perspective of action. Conceptually, a clearer understanding of the logic of expressions such as ‘‘causes’’ and ‘‘correlates’’, and about what to expect from a theory of consciousness are required. The logic of some terms, such as ‘‘qualia’’ and ‘‘reductionism’’, continues to generate misunderstandings about the scientific possibilities and limits. Experimentally, a deeper understanding of the role of the thalamus in coordinating activity across cortical levels, and a readiness to reconsider the orthodox approach to thalamocortical organization are also required.

States of the brain represent states of the world. A puzzle arises when one learns that at least some of the mind/brain’s internal representations, such as a sensation of heat or a sensation of red, do not genuinely resemble the external realities they allegedly represent: the mean kinetic energy of the molecules of the substance felt (temperature) and the mean electromagnetic reflectance profile of the seen object (color). The historical response has been to declare a distinction between objectively real properties, such as shape motion and mass, and merely subjective properties, such as heat, color and smell. This hypothesis leads to trouble. A challenge for cognitive neurobiology is to characterize, in suitably general terms, the nature of the relationship between brain models and the world modeled. We favor the hypothesis that brains develop high-dimensional maps whose internal relations correspond in varying degrees of fidelity to the enduring causal structure of the world. From this perspective, the basic epistemological relation is not “single-percept to single- external-feature” but rather “background-brain-maps to causal-domain-portrayed.