Abstract and Keywords
This introductory article explains the coverage of the book, which is about the connection between philosophy and neuroscience. It discusses the beginning of the philosophy and neuroscience movement in 1986 which coincided with the publication of Patricia Churchland's Neurophilosophy. The text in this book is designed to make direct appeal to data and evidence from some recognized field of current neuroscience. The topics covered by this volume include functional neuroimaging, neuropsychological assessment, and molecular neuroscience.
Research into the brain and nervous system has increased dramatically over the past four decades. Formed in 1970 with around 500 members, the Society for Neuroscience—the premier professional organization for scientists studying the nervous system at all levels—now boasts more than 35,000 members worldwide. Its annual week‐long meeting now offers more than 14,000 scientific presentations, with attendance routinely over 30,000. In the popular media, one rarely picks up or clicks on the science section of a major newspaper or Web site and fails to find a report about a recent neuroscientific discovery. With so much professional scientific and popular interest, it is no wonder that some contemporary philosophers stay tuned. Bringing recent neuroscientific detail into philosophical discussion has opened new inquiries and breathed new life into old disputes. Increasingly one finds “philosophy of neuroscience” and “neurophilosophy” in listings ranging from course titles to individual statements of research specialization.
It seems reasonable to date the explicit start of the philosophy and neuroscience movement to 1986 and the publication of Patricia Churchland's Neurophilosophy. Of course, philosophers had been talking to neuroscientists professionally for many years before, but Churchland's book codified certain fundamentals. It set the stage for the issues that came to dominate the movement for the next two decades. These included focusing on theories (in psychology and the neurosciences) and intertheoretic relationships; militating against functionalism and the autonomy of psychology; and popularizing emerging trends in the cognitive neurosciences (neural networks, functional neuroimaging, and the neural correlates of consciousness come quickly to mind). At first, neurophilosophy served as a useful catch‐all term for these inquiries. But soon philosophers began distinguishing the philosophy of neuroscience, which referred to philosophical reflections on neuroscience's emerging foundational questions. This research quickly took its place among other (p. 4) philosophies of specific sciences. These fields came to dominate English‐speaking philosophy of science in the last decades of the twentieth century, as grand philosophical inquiries into science in general lost appeal. Neurophilosophy in turn came to stand more specifically for the application of neuroscientific discoveries to traditionally philosophical concerns.
“Philosophy and neuroscience” comfortably accommodates both endeavors and more. The more includes ongoing transdisciplinary interactions between philosophers and neuroscientists, where disciplinary boundaries get even blurrier. These inquiries are among the most exciting in all of recent philosophy, and it is time they received a broader professional hearing—hence this volume. There are chapters here that fall within philosophy of neuroscience typically conceived. There are also neurophilosophical chapters. But there are also chapters in which it is difficult to tell where the philosophy starts and the neuroscience ends, where the philosopher stops talking and the neuroscientist starts, and vice versa—even in single‐authored chapters!
The “Philosophy and Neuroscience” title is also intended to bring in an extended audience—professional neuroscientists—and not just for the sake of greater sales. It is time for neuroscientists to see what recent interactions with philosophers have produced for some of their colleagues. The hope here is that the volume will not only inform but inspire. In the preface to Neurophilosophy, Churchland asserted that “it is now evident that where one discipline [neuroscience] ends and the other [philosophy] begins no longer matters, for it is in the nature of the case that the boundaries are ill‐defined” (1986, ix–x). Back then, that slogan only had resonance with philosophers (and mostly only with wide‐eyed Quineans). Gradually, however, it is becoming more than just a philosopher's rallying cry (or plea). The neuroscientists really are starting to pay attention.
So a principal goal of this volume is to give voice to some properly informed philosophers who are beginning to contribute directly to neuroscience. Most have not just waded into neuroscience's shallows but dived right into its practices alongside neuroscientists. This goal informed my choice of contributors, all of whom were invited. Many chapters are from younger scholars who, like me, cut their academic teeth within the first two decades of neurophilosophy. A number of these contributors have recently published or are now writing their first books. The time is thus ripe to showcase the work of these philosophers, providing them with wide latitude on the topics of their entries, in a book series as widely read and influential as the Oxford Handbooks.
I only imposed only two conditions on contributors. First, each chapter had to make direct appeal to data and evidence from some recognized field of current neuroscience. A wide net was cast. Appeals in these chapters range from functional neuroimaging, neuropsychological assessment, and computational neuroscience on down through behavioral and systems neuroscience, to functional micro‐neuroanatomy, neurophysiology, and even molecular neuroscience. Second, I asked each contributor to consider collaborating with a neuroscientist. Coauthorship was not a requirement, and indeed many chapters are single‐authored. (Despite their (p. 5) scientific interests, many philosophers still like to write alone.) But it is also clear, based on the amount and depth of neuroscientific coverage, that no author in this volume learned his or her neuroscience in a vacuum (or a vat).
Because philosophy and neuroscience is a field that continues to define itself, I did not ask contributors to focus on any particular topics, but instead to cover whatever they thought was most interesting. (Another goal of this volume is to characterize and classify the central issues in this field, according to its principal practitioners.) As I expected, most chapters congealed around a familiar set of issues, but in quite novel ways. In the remainder of this brief introduction, I'll list these basic themes and locate the various chapters within them.
Explanation, Reduction, and Methodology in Neuroscientific Practice
An interest in neuroscientific detail has long been correlated with evaluating mind—brain reductionism. A discussion of intertheoretic reduction, for example, occupied one of only four chapters in Churchland's Neurophilosophy that focused directly on philosophical concerns. Yet the traditional accounts of reduction from the philosophy of science have not borne up well in detailed applications to psychology‐to‐neuroscience cases. What relationships might replace these? All four chapters in this initial part address this question by focusing on detailed cases from actual neuroscientific practice. William Bechtel examines the long‐term potentiation (LTP)—memory link, a favorite example of ruthless reductionists, and finds evidence in it instead for mechanistic reduction. He traces the mid‐twentieth‐century history of neuroscience, detailing the split between the ruthless reductionists who went on to become the Society for Neuroscience crowd, and the mechanistic reductionists who went on to develop behavioral, systems, and cognitive neuroscience as we know them today. Sarah Robins and Carl Craver examine recent work on circadian rhythms. They argue that causal‐mechanistic explanations are central to this research, with multilevel mechanisms being the key explanatory posits. Their chapter is one of the more detailed applications in the literature of the “new mechanical” philosophy of science to a neuroscientific case study. Anthony Chemero and Charles Heyser examine the use of the object recognition memory paradigm in rodents, a laboratory favorite of reductionistic neuroscientists searching for cellular and molecular mechanisms of cognition. Their literature review of recent publications employing this procedure, and their own experiences with it as practicing behavioral neuroscientists, however, suggest that not only is mind—brain reductionism false, but its implicit adoption leads to methodologically flawed science. Alcino Silva and John Bickle advocate a new scientific field, the Science of Research, whose goal is to develop and test verifiable hypotheses about scientific practice. Focusing (p. 6) on cases from the young field of molecular and cellular cognition, they argue for two initial science of research hypotheses: the convergent four hypothesis about jointly sufficient conditions for establishing causal connections between phenomena in science, and the nature of actual reductionism within the practices of this reductionistic neuroscientific field.
Learning and Memory
The next section seeks to draw philosophical lessons from recent work in one of neuroscience's hottest fields: learning and memory. Of course, cases from this field are also prominent in chapters in the previous section; here, the philosophical lessons go beyond reduction, explanation, and methodology. Colin Allen, Jim Grau, and Mary Meagher discuss Grau, Meagher, and colleagues' behavioral neuroscientific research into the spinal cord—based learning capacities of spinally transected rats. These phenomena include numerous types of associative learning that fueled the cognitivist revolution in animal experimental psychology during the second half of the last century. This research, they argue, demonstrates that the boundaries of cognition lie beyond the brain itself. Alex Rosenberg details one current neurogenomic model of both implicit and explicit memory, and draws some negative implications for key aspects of computationalism in the philosophy of mind and psychology. However, his upshot is not entirely negative. Drawing on some comparisons between neurogenomics and developmental biology more generally, he argues that computationalism's emphasis on syntactic programs seems on its way toward neurobiological vindication. Peter Machamer employs citation indexes as a measure of particular papers' influence, and based on the highest cited papers, he argues that behaviorist methodologies remain prominent within current neuroscience. The specific nature of these methodologies creates a novel challenge for generalizing the experimental results to a full account of human learning and memory, one quite different from the standard challenges that defined the twentieth‐century cognitivist revolution against behaviorism.
Sensation and Perception
Another area of great research interest and productivity in recent neuroscience has been sensation and perception. These results likewise generate interesting philosophical concerns. Valerie Hardcastle and Matthew Stewart remind us of long‐standing philosophical speculation about cerebroscopes, devices that can read the brains of oneself and others, and ponder whether the modern technique of functional magnetic resonance imaging (fMRI) realize those philosophical speculations. (p. 7) They turn specifically to attempts to image the brain in pain and point out serious methodological problems with this research. Nevertheless, they also point out that more than four years ago the Institute for Biodiagnostics of the National Research Council of Canada had already suggested that fMRI is potentially a cerebroscope for pain.
The other three chapters in this part speak to recently popular enactivist accounts of perception. Mazviita Chirimuuta and Ian Gold argue that some recent results from visual neuroscience cast doubt on the standard notion of a visual neuron's receptive field, at least in the sense that won David Hubel and Torsten Wiesel half of the 1981 Nobel Prize for Physiology or Medicine, and has since informed the hierarchical model of visual processing in the mammalian brain. They present numerous attempts to patch up the classical notion to account for these data, ranging from conservative extensions to radical replacements. One potential replacement they find intriguing, if not yet very well confirmed by experimental data, brings in resources from enactivist theories of perception. The response properties of visual neurons may reflect the complex interactions between perceiver and environment. Critical responses to enactivist theories dominate the final two chapters. Brian Keeley asks how enactivists propose to differentiate the senses and finds their account wanting in various empirical respects. The details of a pheromone‐detecting vomeronasal sense seems in tension with what enactivist Alva Noë has said about it, as do the details of various visual prosthetic devices. Keeley argues that we're left with a crucial role for neurobiological research in differentiating the senses, a role he traces back to Aristotle and through the history of late‐nineteenth‐century neurobiology (specifically to Müller's law of specific nerve energies). Charles Wallis and Wayne Wright give enactivism a comprehensive cognitive‐neuroscientific shakedown, and find it sorely lacking. They argue that not only have enactivists misdescribed the few neuroscientific details they've appealed to in defending their views, but that no evidence exists (yet) for the neural realization of the sensorimotor contingencies that ground enactivist theory.
Neurocomputation and Neuroanatomy
Neural networks have been central to philosophy and neuroscience since Rumelhart and McClelland put together the two‐volume Parallel Distributed Processing manifesto in 1986. Yet many philosopher fans of neural networks didn't keep up with developments in actual computational neuroscience. The authors in this section are strong exceptions to this common neglect. Rick Grush describes the computational details of his emulator framework and his previous applications of it to representations of egocentric (behavioral) space. He also applies it to behavioral time, including to some paradoxes of time consciousness made famous to philosophers by Daniel Dennett. He also discusses some novel neurophysiological work (p. 8) that suggests mechanisms of the emulator framework in mammalian cortex. Chris Eliasmith summarizes the basic principles of his neural engineering framework and its detailed application to modeling neural phenomena at various levels. He articulates lessons for philosophical topics ranging from levels in neuroscience and the relations between them, theory construction in the behavioral sciences, and the possibility and nature of a semantics for the resulting account of mental representations. Christopher Cherniak explains his group's work on brain wiring circuitries, providing an answer to the seeming paradox that nature hits on close‐to‐optimal wiring designs in brains, despite the limits of available space and the number of components. How does nature accomplish this? Cherniak draws inspiration from the anthropic principle of contemporary cosmology, generating an answer that potentially narrows the “hardware‐independence” thesis of classic computational psychology.
Neuroscience of Motivation, Decision Making, and Neuroethics
Neuroethics is one area of philosophy and neuroscience that has made a significant mark on the broader philosophical community. It connects up with recent developments in social and affective neuroscience and has started to spawn related disciplines like neurolaw. But behavior and decision making in ethical situations are paradigmatically motivated, and so neuroethics might learn something from the latest work on the neuroscience of motivation. Anthony Landreth presents an account of this work, beginning with a well‐known philosophical analysis. He grounds components of that analysis in a computational model drawn from reinforcement learning theory, and then suggests how components of the model might be realized by phasic and tonic activity in dopaminergic neurons in the midbrain and orbitofrontal cortex. Patricia Smith Churchland addresses the classic challenge to all naturalized ethical projects, the maxim of “no derivation of an ought from an is.” She argues that ethical decision making isn't derivational but case‐based. Thus, no logical prohibitions block strong nondeductive inferences of this sort to ought conclusions. She also grounds case‐based ethical reasoning within both neuroevolutionary and neural network accounts. Adina Roskies surveys the comparisons and contrasts between neuroethics and more well‐known genethics, arguing that the special causal proximity of brain to behavior generates unique ethical concerns. She documents four areas of recent neuroethical inquiry and some tantalizing ethical issues that have been raised in each. Eric Racine and Judy Illes consider possibilities for neural enhancement based on recent advances in brain—machine interfaces. They classify a variety of different kinds of ethical considerations that these developments raise. Then they argue that only an emergentist account of mind—brain (p. 9) relations, as opposed to strong reductionist and dualist accounts, can make sense of this full variety of ethical concerns.
Neurophilosophy and Psychiatry
Psychiatry over the past few decades has grown increasingly brain‐based, and some philosophers have followed this trend. William Hirstein describes and classifies a variety of bizarre delusions of persons and their limbs, many replete with confabulatory symptoms. These patients make seemingly confident claims for which epistemologically strong counterevidence is readily available and often presented directly to them. Hirstein surveys the neural basis of these symptoms and suggests lessons for philosophical concerns such as rationality, our knowledge of the external world, and agency. Jennifer Mundale and Shaun Gallagher adjudicate a debate about delusional experience. Are delusional experiences immediate and noninferential, or rather the result of mistaken cognitive interpretations of relatively intact basic experiences? Based on both neural and phenomenological considerations, they defend the first option. Yet they also seek to integrate the concerns that have spawned top‐down cognitive‐processing accounts. Kenneth Sufka, Morgan Weldon, and Colin Allen provide a novel approach to the old question of whether nonhuman animals experience emotions similar to those of humans. The traditional approach is to seek structural homologies across species. Instead, they draw on research in which animals are used to model various features of neuropsychiatric disorders whose core symptoms involve changes in emotional processing. Their investigations produce a set of criteria implicit in this research to validate animal models in terms of shared etiologies, symptomatologies, pathophysiologies, and responses to treatments.
The final section addresses some concerns squarely within neurophilosophy—the application of neuroscience results to reformulate and address traditional philosophical problems. Ken Aizawa and Carl Gillett insist that despite a recent flurry of philosophical challenges to the multiple realization argument about mental and physical kinds, neuroscientists readily accept a massive multiple realization hypothesis about human psychology. They defend this assertion with numerous detailed examples from recent neuroscience and locate it within a developed metaphysics of the realization relation. Their hypothesis need not trouble advocates of the importance of neuroscience for psychology, because this dependence is a consequence of their view (as opposed to the autonomy of psychology championed by some (p. 10) proponents of multiple realization). Owen Flanagan considers some grand claims about finding the neural seat of happiness based on behavioral and functional neuroimaging experiments on Buddhist priests. According to Flanagan, these claims, made by the neuroscientists doing the research and reported widely in the popular media, fail to acknowledge obvious limits on the experimental designs and results. They also fail to distinguish a variety of distinct types of happiness. Far more cautionary interpretations are warranted now, though the potential for future breakthroughs exists. Pete Mandik further develops his views on the neurobiological basis of subjectivity. Subjectivity is taken by many philosophers to be the defining feature of conscious experience, and some of these philosophers argue that no amount of neuroscientific data will ever illuminate it. Mandik provides both philosophical and neuroscientific evidence for an eliminativist conclusion (of sorts) about subjectivity. He argues that evidence exists for denying that we perceptually and introspectively experience properties that may be known in no other way.
The future of philosophy and neuroscience is difficult to foresee. Which (if any) of the topics making up this volume will generate future breakthroughs and interest? As neuroscience continues to develop, will it leave the use for philosophical reflection behind, or at least restrict it to professional philosophers? What new and revolutionary discoveries are waiting just over neuroscience's horizon, and will any of these spark new philosophical insights? None of us has a crystal ball, but we can hope that this volume, which purports to report the current state‐of‐the‐art in this field, will keep some people pushing the traditional boundaries in the humanities, social sciences, and natural sciences.