Conscious Realism and the Mind-Body Problem - UCI Cognitive ...

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106 HoffmanHere there is good news. We have substantial progress on the mindbodyproblem under conscious realism, and there are real scientific theories.We now have mathematically precise theories about how one typeof conscious agent, namely human observers, might construct the visualshapes, colors, textures, and motions of objects (see, e.g., Hoffman 1998;Knill and Richards 1996, Palmer 1999).One example is Ullman’s (1979) theory of the construction of threedimensionalobjects from image motion. This theory is mathematicallyprecise and allows one to build computer-vision systems that simulate theconstruction of such objects. There are many other mathematically precisetheories and algorithms for how human observers could, in principle,construct three-dimensional objects from various types of image motions(e.g., Faugeras and Maybank 1990, Hoffman and Bennett 1986, Hoffmanand Flinchbaugh 1982, Huang and Lee, 1989, Koenderink and van Doorn1991, Longuet-Higgins and Prazdny 1980). We also have precise theoriesfor constructing three-dimensional objects from stereo (Geiger et al. 1995,Grimson 1981, Marr and Poggio 1979), shading (Horn and Brooks 1989),and texture (Aloimonos and Swain 1988, Witkin 1981). Researchers debatethe empirical adequacy of each such theory as a model of humanperception, but this is just normal science.Almost without exception the authors of these perceptual theories arephysicalists who accept HFD and conceive of their theories as specifyingmethods by which human observers can reconstruct or approximate thetrue properties of physical objects that, they assume, exist objectively,i.e., independently of the observer (a claim about physical objects thatis explicitly denied by conscious realism). But each of these perceptualtheories can equally well be reinterpreted simply as specifying a methodof object construction, not reconstruction. The mathematics is indifferentbetween the two interpretations. It does not require the hypothesisof independently existing physical objects. It is perfectly compatible withthe hypothesis of conscious realism, and the mind-dependence of all objects.So interpreted, the large and growing literature in computationalvision, and computational perception more generally, is concrete scientificprogress on the mind-body problem, as this problem is posed by consciousrealism. It gives mathematically precise theories about how certain consciousagents construct their physical worlds. The relationship betweenthe conscious and the physical is thus not a mystery, but the subject ofsystematic scientific investigation and genuine scientific theories.What one gives up in this framework of thinking is the belief thatphysical objects and their properties exist independently of the consciousagents that perceive them. Piaget claimed that children, at about ninemonths of age, acquire object permanence, the belief that physical objectsexist even when they are not observed (Piaget 1954; but see Baillargeon1987). Conscious realism claims that object permanence is an illusion. It
Conscious Realism and the Mind-Body Problem 107is a useful fiction that substitutes for a situation which, for the child, istoo subtle to grasp: Something continues to exist when the child stopsobserving, but that something is not the physical object that the childsees when it observes. That something is, instead, a complex dynamicalsystem of conscious agents that triggers the child to create a physicalobjecticon when the child interacts with that system. For the child it ismuch simpler, and rarely problematic, to simply assume that the physicalobject it perceives is what continues to exist when it does not observe.Indeed, only when one faces the subtleties of, e.g., quantum theory orthe mind-body problem, does the utility of the illusion of object permanencefinally break down, and a more sophisticated, and comprehensive,ontology become necessary.With physicalist approaches to the mind-body problem, one faces a difficultquestion of causality: If conscious experience arises somehow frombrain activity, and if the physical world is causally closed, then how, precisely,does conscious experience cause anything ? It seems, for instance,that I eat pistachio ice cream because I feel hungry and I like the tasteof pistachio. Do my conscious experiences in fact cause my eating behaviors? No, say non-reductive functionalists, such as Chalmers (1996),who claim that functional properties of the brain give rise to, but are notidentical with, conscious experiences. Instead they often endorse epiphenomenalism:Brain activity gives rise to conscious experiences but, sincethe physical realm is causally closed, conscious experiences themselveshave no causal consequences. It seems like I eat pistachio because ittastes good, but this is an illusion. Moreover, I believe that I consciouslyexperience the taste of pistachio, but I would believe this whether or notI in fact consciously experience this taste. This is a radical claim andclose to an outright reductio of the position. Reductive functionalists, bycontrast, do not endorse epiphenomenalism, since they claim that consciousexperiences are identical to certain functional states of the brain,and conscious experiences therefore possess the causal properties of thosefunctional states. However, reductive functionalism has recently been disprovedby the “scrambling theorem” which shows that, if one grants thatconscious experiences can be represented mathematically, then consciousexperiences and functional relations are not numerically identical (Hoffman2006).Conscious realism leads to a different view of causality, a view I callepiphysicalism: Conscious agents are the only locus of causality, and suchagents construct physical objects as elements of their MUIs; but physicalobjects have no causal interactions among themselves, nor any othercausal powers. Physical objects, as icons of a conscious agent’s MUI, caninform, but do not cause, the choices and actions of a conscious agent.When a cue ball hits an eight ball and sends it careening to the cornerpocket, the cue ball does not cause the movement of the eight ball any
Page 6 and 7: 92 Hoffmanthen the visual system in
Page 8 and 9: 94 Hoffmanwhat it represents. Inste
Page 10 and 11: 96 Hoffman4. Virtual WorldsSuppose
Page 12 and 13: 98 HoffmanThis counterexample is in
Page 14 and 15: 100 HoffmanA fifth argument: Ideas
Page 16 and 17: 102 Hoffmansupercomputer is vastly
Page 18 and 19: 104 Hoffman2003). Exegesis of Kant
Page 22 and 23: 108 Hoffmanmore than the movement o
Page 24 and 25: 110 Hoffmanconscious agent, we both
Page 26 and 27: 112 Hoffmancreatures that thrived l
Page 28 and 29: 114 Hoffmanlutionary considerations
Page 30 and 31: 116 Hoffmangrateful. Sole responsib
Page 32 and 33: 118 HoffmanGibson J.J. (1950): The
Page 34 and 35: 120 HoffmanRizzo M., Nawrot M., and

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