Two other recent attempts to provide empirical grounds for dualism have appeared in The Behavioral and Brain Sciences (with the usual barrage of expert counterattack and rejoinder): Roland Puccetti and Robert Dykes’s “Sensory Cortex and the Mind-Brain Problem,” BBS (vol. 3, 1978, pp. 337–376), and Roland Puccetti, “The Case for Mental Duality: Evidence from Split-Brain Data and other Considerations,” BBS (1981).
Nagel addresses his musings on what it is like to be a bat against a “recent wave of reductionist euphoria,” and cites as examples: J.J.C. Smart, Philosophy and Scientific Realism (London: Routledge & Kegan Paul, 1963); David Lewis, “An Argument for the Identity Theory,” in Journal of Philosophy (vol. 63, 1966); Hilary Putnam, “Psychological Predicates,” in Art, Mind, and Religion, edited by W.H. Capitan and D.D. Merrill (Pittsburgh: University of Pittsburgh Press, 1967), and reprinted in Putnam’s Mind, Language and Reality; D.M. Armstrong, A Materialist Theory of the Mind (London: Routledge & Kegan Paul, 1968); and Daniel Dennett, Content and Consciousness. On the opposing side of the issue he cites Kripke’s “Naming and Necessity,” M.T. Thornton, “Ostensive Terms and Materialism,” The Monist (vol. 56, 1972, pp. 193–214), and his own earlier reviews of Armstrong, in Philosophical Review (vol. 79, 1970, pp. 394–403), and Dennett, in Journal of Philosophy (vol. 69, 1972). Three other important papers in the philosophy of mind are cited by him: Donald Davidson, “Mental Events,” in L. Foster and J.W. Swanson, eds. Experience and Theory (Amherst: University of Massachusetts Press, 1970), Richard Rorty, “Mind-Body, Identity, Privacy, and Categories,” in Review of Metaphysics (vol. 19, 1965, pp. 37–38); and Nagel’s own “Physicalism,” in Philosophical Review (vol. 74, 1965, pp. 339–356).
Nagel has extended his imaginative work on subjectivity in “The Limits of Objectivity,” three lectures published in The Tanner Lectures on Human Values (New York: Cambridge University Press, and Salt Lake City: University of Utah Press, 1980), edited by Sterling McMurrin. Other imaginative work on the topic includes Adam Morton’s Frames of Mind (New York: Oxford University Press, 1980) and Zeno Vendler’s “Thinking of Individuals,” in Nous (1976, pp. 35–46).
The questions raised by Nagel have been explored in many recent works. Some of the best discussion is reprinted in Ned Block’s two-volume anthology, Readings in Philosophy of Psychology (Cambridge, Mass.: Harvard University Press, 1980, 1981), along with many other articles and chapters on the topics encountered in The Mind’s I. For some fascinating thought experiments about how a different understanding of science might change what it is like to be us, see Paul Churchland’s Scientific Realism and the Plasticity of Mind (New York: Cambridge University Press, 1979).
A careful discussion of the mirror problem is Ned Block’s “Why Do Mirror Reverse Right/Left and Not Up/Down?” in the Journal of Philosophy (1974, pp. 259–277).
The perception of color, which Smullyan exploits in “An Epistemological Nightmare,” has often been discussed by philosophers in the guise of the inverted spectrum thought experiment, which is at least as old as John Locke’s Essay Concerning Human Understanding (1690, book 2, chap. 32, par. 15). How do I know that I see what you see (in the way of color) when we both look at a clear “blue” sky? We both learned the word “blue” by being shown things like clear skies, so our color-term use will be the same, even if what we see is different! For recent work on this ancient conundrum, see Block’s anthology, and Paul and Patricia Churchland’s “Functionalism, Qualia, and Intentionality,” in Philosophical Topics (vol. 12, no. 1, spring 1981).
The fantasies and thought experiments in this book are designed to make one think about the hard-to-reach corners of our concepts, but sometimes perfectly real phenomena are strange enough to shock us into a new perspective on ourselves. The facts about some of these strange cases are still hotly disputed, so one should read these apparently straightforward factual accounts with a healthy helping of skepticism.
Cases of multiple personalities—two or more persons “inhabiting” one body for alternating periods of time—have been made famous in two popular books, The Three Faces of Eve (New York: McGraw-Hill, 1957), by Corbett H. Thigpen and Hervey M. Cleckley, and Sybil (Warner paperbacks, 1973), by Flora Rheta Schreiber. Both books have been made into motion pictures. It should be apparent that nothing in the theories sketched or implied by the fantasies and reflections in this book would rule out multiple personality as impossible. Still, it may be that the recorded cases, however scrupulously described in the literature, have been too much the products of their observers’ theoretical expectations, rather than phenomena that had a crisp and well-defined existence before being studied.
Every experimentalist knows the insidious dangers of the inherent and inescapable bias with which a curious scientist faces the phenomena to be studied. We usually know what we hope to discover (for we usually know what our pet theory predicts), and unless we take great pains to prevent it, that hope may fool our eyes and ears, or lead us to lay down a subtle trail of hints to our subjects about what we expect from them—without us or our subjects realizing it. Laundering these “demand characteristics” out of experiments and using “double-blind” techniques of experimentation (where neither the subject nor the experimenter knows, at the time, which condition—test or control—is in effect) takes care and effort, and requires a highly artificial and constrained environment. Clinicians—psychoanalysts and doctors—exploring the strange and often tragic afflictions of their patients simply cannot and must not try to conduct their dealings with their patients under such strict laboratory conditions. Thus it is very likely that much of what has been honestly and conscientiously reported by clinicians is due not just to wishful thinking, but to wishful seeing and hearing, and to the Clever Hans effect. Clever Hans was a horse who astonished people in turn-of-the-century. Berlin with his apparent ability to do arithmetic. Asked for the sum of four and seven, for instance, Hans would stamp a hoof eleven times and stopwith no apparent coaching from his master, and with success over a wide variety of problems. After exhaustive testing, skeptical observers determined that Hans was being cued to stop stamping by a virtually imperceptible (and quite possibly entirely innocent and unintended) intake of breath by his trainer when Hans arrived at the correct number. The Clever Hans effect has been proven to occur in many psychological experiments with human beings (a faint smile on the experimenter’s face tells the subjects they’re on the right track, for instance, though they don’t realize why they think so, and the experimenter doesn’t realize he’s smiling).
Clinical marvels such as Eve and Sybil, then, ought to be studied under laboratory conditions before we embark on serious efforts to accommodate our theories to them, but in general that has not proven to be in the best interests of the patients. There was, however, at least one striking study of Eve’s dissociated personality, a partially “blind” study of her—their?—verbal associations, by a method that revealed three very different “semantic differentials” for Eve White, Eve Black, and Jane (the apparently fused person at the close of therapy). This is reported in C.E. Osgood, G.J. Suci, and P.H. Tannenbaum’s The Measurement of Meaning (Champaign: University of Illinois Press, 1957). A recent report of a newly discovered apparent case of multiple personality is Deborah Winer’s “Anger and Dissociation: A Case Study of Multiple Personality,” in the Journal of Abnormal Psychology (vol. 87, (3), 1978, pp. 368–372).