The nature of the mind and its relationship
to the body have long been objects of intense investigation by philosophers.
With the rise of modern science, questions that were once the concern
of philosophers exclusively have become amenable to empirical investigation
and, most recently, to investigation through the methods of cognitive
neuroscience. As the concerns of philosophy and "hard science" continue
to merge, investigators from both traditions are increasingly in a
position to contribute to each others' projects. Two examples of such
interdisciplinary work undertaken by philosophers at the CSBMB are
described below.
Phenomenology and the Science of PerceptionThere is a long tradition of philosophical attempts to think about the nature of perception. In the second half of the 20th century these attempts have been motivated by at least three kinds of observations. In the first place, perceptual experiences are often understood to be intentional they are of, about, or directed towards objects, events, or states of affairs in the world. In the second place, perceptual experiences seem to be connected with certain kinds of thoughts. A particularly salient class of these thoughts are the perceptual demonstrative thoughts thoughts like "that cup", for instance, said in the perceptual presence of a cup. But finally, there is significant phenomenological evidence to suggest that the content of the experience isnıt reducible to the content of the thought had on the basis of it. Seeing the cup seems, in some sense, to be a "richer" kind of thing than having a thought about it. A project being undertaken by Sean Kelly attempts to bring together all these observations and, in the light of further empirical data, form a story about the content of certain kinds of perceptual experiences and the thoughts they make possible.The project is motivated by some startling results from recent brain research. These results involve a patient with severe brain damage who suffers from a failure to recognize visual shapes. This condition is called "visual form agnosia". Interestingly, despite her inability to recognize the shape of objects, this patient, D. F., has no apparent difficulty performing visually guided actions that require the processing of those very visual shapes. In other words, although she cannot recognize the shape of objects presented to her, she has no problem acting differentially with respect to them. To account for this, the neuroscientists A. David Milner and Melvyn Goodale have hypothesized a perceptual mechanism that is "geared to action, in contrast to judgmental 'seeing'". In particular, they believe that one of the two major streams of visual processing in the cerebral cortex, the so-called dorsal visuo-cortical stream, is primarily responsible for the visual guidance of actions. If correct, Milner and Goodale's hypothesis would overthrow the standard interpretation of the relative roles of the two major streams of visual information processing. On the standard interpretation, the so-called ventral stream provides conceptual information about "what" the perceived object is (its size, shape, color, etc.), while the dorsal stream provides information about "where" the perceived object is (perhaps in a body-centered space). According to Milner and Goodale, however, these streams should be understood as providing "what" and "how" information. On this hypothesis, the dorsal stream doesnıt just tell us where a perceived object is, it tells us how to act bodily with respect to it. This information must be encoded in a language of potential bodily actions, instead of in a language of locative concepts or thoughts. This general idea is pre-figured in the phenomenological work of Maurice Merleau-Ponty and is in sympathy with the psychological account of perception developed by J. J. Gibson. Such an empirical result, if correct, would have important implications for philosophical accounts of perception and perceptual demonstrative thought as well. In particular, one influential philosophical account of the content of perceptual experience, developed by Gareth Evans, is also based on the (now apparently erroneous) idea that in perceiving an object we receive information about where that object is located (relative to us). Evans uses this idea to develop an account of the relationship between perceptual content and the content of perceptually based demonstrative thoughts. In order to have a perceptually based demonstrative thought about an object, Evans argues, it is sufficient to know its objective location. On the assumption that perceiving an object tells us its location relative to us, the perceptual act provides at least some of the information necessary to form a demonstrative thought about the object being perceived. To get the rest, Evans posits some "general cognitive capacities" which allow us to infer the objective location of an object from its location relative to us. He thus claims to show how perception makes possible demonstrative thought. If Milner and Goodale are right in arguing that the dorsal stream provides us with "how" instead of "where" information, however, then Evansıs account of perceptual content is wrong: it is based on the erroneous idea that perceptual content is merely locative. This error carries over to his account of the relation between perceptual and demonstrative content as well. Kelly proposes, therefore, to re-think Evansıs approach to these problems by focussing on the following questions:
Emotion and Cognition in Moral Judgment: An fMRI InvestigationConsider the following moral dilemma. A trolley is heading down a set of tracks toward five people who will be killed if it proceeds on its present course. You can save these five people by diverting the trolley onto a different set of tracks, one that has only one person on it, but if you do this that person will be killed. Is it morally permissible to turn the trolley and thus prevent five deaths at the cost of one? Most people say yes. Now consider a slightly different dilemma. Once again, a trolley is heading down a set of tracks toward five people. You are on a footbridge over the tracks next to a large man. The only way you can save these five people is to push this man off the bridge and into the path of the trolley. Is that morally permissible? Most people say no.These two cases create a puzzle for moral philosophers (at least for those who take moral intuitions at face value): What makes it okay to sacrifice one for the sake of five in the first case but not in the second case? But there is also a psychological puzzle here: How does everyone know (or "know") that it's okay to turn the trolley but not okay to push the man off the bridge? One hypothesis is that we have an implicit understanding of a complex set of shared moral principles from which we deduce our answers. According to this theory our responses are, in both cases, the results of "cool" reasoning. A different hypothesis appeals to common emotional response rather than shared principles. The thought of pushing someone to his death with one's bare hands is, we'll suppose, more emotionally salient than the thought of hitting a switch that will have similar consequences. Somehow, the action described in the second case sets off an emotional "moral alarm" in each of us. According to this theory, our shared dispositions to respond emotionally to some things and not others explains the consistency found in people's reactions to these two cases. "Cool" reasoning and emotional response are associated with different parts of the brain. While our understanding of these psychological functions and their neural substrates is far from complete, we are in a position to use the above theories to generate predictions about the brain's activity and to test these predictions using fMRI (functional Magnetic Resonance Imaging). Such a study is being carried out by Joshua Greene (Graduate Student, Dept. of Philosophy) under the supervision of Jonathan Cohen (Director, CSBMB; Professor of Psychology) and with the help of Brian Sommerville (Research Assistant, CSBMB) and John Darley (Professor of Psychology). |