Review of: Mental Content. COLIN MCGINN. Oxford, New York: Basil Blackwell, 1989. vi, 215 p. Cloth

 

Pierre Jacob,

Groupe de recherche sur la cognition,

CREA,

CNRS/Ecole Polytechnique,

1, rue Descartes,

75005 Paris, France.

 

 

            According to externalism, a thinker's environment contributes to the contents of many of his or her propositional attitudes. Colin McGinn's book, Mental Content, is a welcome contribution to the assessment of the scope, limits and implications of externalism. Granted, the contrast between facts internal to, and facts external to, a person or individual might seem somewhat elusive. Nonetheless, if externalism is correct, then not all of a person's mental properties are (intrinsic or monadic) properties of his or her brain. Nor do all of a person's mental properties supervene on physical properties of his or her brain. Some at least involve relations between an individual's brain and his or her nonmental environment. Admittedly, this version of externalism depends on an indiscriminate concept of a person's environment. Early on (fn 5, p. 2) McGinn rightfully (in my opinion) distinguishes the contribution the "nonmental world" might make to the content of a person's mind ("externalism" proper) from the contribution possibly made to the content of a person's mind by what other minds in his or her community may think ("anti-individualism").

            If correct, externalism has many far reaching philosophical consequences upon the epistemology of mental states, first person authority (about the content of a person's own mind), personal identity, scepticism, the nature of mental properties, physicalism, mental causation and the role of content in scientific psychology. Is it correct?

            McGinn diagnoses the major source of resistance to externalism in substantialism, the view that the mind is a substance (14-30, 100-103): "if externalism were true of the mind, then it could not have the substantial nature of the body or brain" (17, 23, 116). So consider e.g., personal identity. If some of a person's mental properties change when his or her environment changes, then it might seem that his or her personal identity might concomitantly be affected. This is a consequence McGinn deflects by distinguishing what confers upon a person his or her mind from what makes a person the person he or she is (3, 24-26, 46): whereas a person is, a mind is not, a substance (25).

            At the core of the book is McGinn's distinction between strong and weak externalism (7-9). According to strong externalism, unless a thinker causally interacts with a particular spatio-temporal item present in his or her nonmental environment, he or she could not entertain a thought with a particular content. Prime candidates for strong externalism are contents of thoughts about particular spatio-temporal material objects and primitive (nondefinable) natural kind concepts. According to weak externalism, unless property P is instantiated by a particular item somewhere or other in the nonmental world, a thinker could not entertain a thought one constituent of which is a concept denoting or expressing P. Candidates for weak externalism are abstract arithmetical or geometrical properties and perceptual content.

            McGinn's book is a critique of "total strong externalism". The crux of his argument is that property realism and a teleological account of content, both of which McGinn favors, conspire to entail a weak externalist view of some contents.

            What is relevant to e.g., perceptual content is less its causes than its behavioral effects (58-99): while I have the visual experience as of a square shaped building prompted by my perceiving a square building in the actual world, my twin may, the weak externalist claims, have an indistinguishable visual experience prompted by a round building transmitted by warped light rays on twin earth. Guided by the same perceptual content, we may both exhibit the same squarewise driving behavior. McGinn takes the strong externalist verdict of a mismatch between my twin's perceptual content and his behavior on twin earth as a refutation of total strong externalism (65-66). But now, if some contents are weakly external, then total internalism is false and so is total strong externalism. I will argue that weak externalism generates a dilemma between naturalism and property realism.

            Mental Content has three parts. In the first part ("The Location of Content" which occupies over half the book), McGinn does two things: he lays out his metaphysics and he probes the applicability of (weak and strong) externalism to a variety of different mental contents. As the second part of the book, "The Utility of Content," makes clear, McGinn's outlook is broadly naturalistic and falls squarely in the recent tradition of teleological accounts of content1 which, he says, he "was slow to come round to" (143). In the third part, he espouses the mental model view of what he variously calls the "basis," the "ground" or the "mechanism" of content.2

            There is a connection between the teleological account of content advocated in Part II and the mental model view of the "basis" (or "ground") of content advocated in Part III. In the latter, McGinn addresses what he takes to be an "engineering" or a "design" task - a task he calls "Psychotectonics." Roughly, the task is to build a machine which "invites the assignment of propositional items, not to say what these assigned items themselves consist in" (170-72). McGinn thinks there are two major competing views which may claim to do the job: Jerry Fodor's sententialist hypothesis of a language of thought3 and the mental model view. McGinn believes (182) that once the confusion between the "ground" or "mechanism" of content and the (propositional) "object" or "target" is cleared up, then the mental model picture can be seen to be the correct view of the former.

            His reason lies in the analogy between the role of (abstract) propositions as indices in assigning contents to mental states and the role numbers play in scientific measurement as indices of physical magnitudes (107, 139-43, 182-83, 187). One anti-Fodorian consequence of the indexing analogy between contents and numbers is that "logical structure" need no more be "literally in the head" than "indices need... in general be in what they index" (183). However, unlike assignment of numbers in measurement, assignment of (propositional) content to mental states has a teleological point (142): the content of a representational state is linked to the function the state has in delivering valuable information for the benefit of the organism whose state it is.4 Both the analogy and the disanalogy between numerical indices in measurement and propositional indices in content assignment loom large in McGinn's project since he depends on them for his argument that content is suitable for scientific psychology.

            Since Putnam's seminal thought experiment,5 philosophers have disagreed about the suitability of content for a naturalistic approach to the mind or for scientific psychology. I found McGinn's criticism of Churchland's charge that contentful folk psychology is a degenerate stagnant research program insightful (123-26).6 So did I find his discussion of Stich's castigation of content and defense of a syntactic scientific psychology and Putnam's dichotomy between algorithmic, computational, subpersonal scientific psychology and informal, holistic, personal, normative content-based interpretation theory (127-32).7 McGinn's conclusion is "not... to banish content from the science of psychology" (132, 156), but to recognize that biology, not physics, ought to be the proper paradigm for scientific psychology. One assumption used to reach the conclusion is that subpersonal content of the kind ascribed either in low level human visual information processing or to nonhuman animals, though no less content than the content of propositional attitudes, is less subject to hermeneutic perplexities.

            Whereas he sees (rightly in my opinion) no tension between externalism and a physicalist ontology (103-105), McGinn takes very seriously the puzzle externalism generates for mental causation, i.e., the threat that the mental be epiphenomenal. The puzzle arises from the tension between three views: the externalist view that some content is relational (or extrinsic to an individual's brain); the view that, however relational, content may be a causally efficacious property; and the view (which McGinn espouses) that all causation is a local process (133-137). Pondering over this tension, many philosophers have recently worried whether physical properties of an individual's brain do not screen off or preempt mental properties from causal efficacy or causal relevance.8

            McGinn "concedes" the epiphenomenalism of the mental and he argues that the concession will seem fatal only to philosophers in the grip of physics worship. On his view, genuine causal explanations are physical explanations: they must refer to physical properties of mechanisms. "Content cannot be saved on the strength of what it takes for the causal wheels to turn" (149). However, he insists "that there is more to explanation than simply citation of causes" (144). His explanatory vindication of content is threefold. First, from the indexing analogy between numbers and contents, he argues that contents are neither more nor less causally efficacious, hence neither less nor more explanatorily respectable, than numbers (141). Second, he argues, in biology, not only does the information supplied by "teleological taxonomies" differ from, and complement, the information supplied by "causal taxonomies" (145-46), but the "biological function of a trait, mental or bodily, cannot be revealed by examination of the causal mechanisms" (149). Finally, from the teleological account of content, he argues that content is neither better nor worse off than the biological function of a trait.

            Let me now go back to "the crux" of McGinn's argument against total strong externalism. One obvious rationale for the distinction between strong and weak externalism is that it provides a neat alternative to the distinction between broad and narrow conceptual contents.9 Natural kind concepts are strongly external. The perceptual content of a sensory experience is weakly external.10 Therefore the conceptual content of my water beliefs differs from the conceptual content of my twin's twater beliefs. However, the perceptual content of my experience triggered by my perception of a glass of water and the perceptual content of my twin's experience when he perceives a glass of twater are indistinguishable - an assumption clearly made in Putnam's seminal thought experiment.11

            Why does the teleological account of content support weak externalism? The reason is that "contentful states can in principle have a function that is specified by reference to a property that is not actually instantiated in the organism's causally impinging environment... a function could in principle exist without that function ever actually being fulfilled" (67). Why does property realism support weak externalism too? The reason is that, on McGinn's view, "properties are mind-independent and objective" (fn 130, p. 116) and "we simply have no other conception of e.g., the concept square than as something that denotes the property of being square" (fn 57, p. 41). It is, McGinn believes, a condition of adequacy on any theory of content, that it solves what he calls (11-12) "the matching problem:" How do concepts match (or "latch onto") properties of things? On McGinn's "naive realist" view, mind-independent objective properties have a dual role or may enter into two distinct relations with objects: they may be instantiated by, or predicated of, objects. If an object instantiates a property and if an individual's thought predicates the latter of the former, then the thought is true.

            Here is the dilemma an advocate of weak externalism, I think, faces: either for me to correctly ascribe the property of being square, I must causally interact with square-shaped spatio-temporal particulars in my environment, or not. If the former, strong externalism is vindicated. But McGinn cannot take this option, since on his view, the concept of a square shape is typically an "observational" concept (59) to which weak externalism applies as it does to perceptual content. If the latter, then either naturalism is false or property realism is false: either the mind has the nonnatural power to reach out into the world to the property of being square uninstantiated in its environment or being square is a projection from my concept. Suppose "possessing the concept square cannot consist in anything other than standing in some relation (the intentional relation) to that property" (fn 57, p. 41). Unless being square is a projection of my concept of a square, my mind, it seems, will not stand in relation to this property if the latter is not instantiated in my environment. But this is to give up property realism.

 

 

 

 

1. See F. Dretske, "Misrepresentation," in R. Bogdan (ed.) Belief (Oxford: Clarendon Press, 1986); J.A. Fodor, A Theory of Content (Cambridge, Mass.: MIT Press, 1990); R.G. Millikan, Language, Thought and Other Biological Categories (Cambridge, Mass.: MIT Press, 1984); D. Papineau, Reality and Representation (Oxford: Blackwell, 1987).

2. A view he ascribes to Cambridge psychologist Kenneth Craik and which has been recently rehabilitated by Cambridge psychologist Philip Johnson-Laird, Mental Models (Cambridge: Cambridge University Press, 1983).

3. Cf. J.A. Fodor, The Language of Thought (New York: Crowell, 1975) and Psychosemantics, The Problem of Meaning in the Philosophy of Mind (Cambridge, Mass.: MIT Press, 1987).

4. McGinn suggests that computers, which are are purely syntactic engines, lack altogether "original teleology," "affective or conative states" and intentionality (155): "intentionality begins with wanting,... not thinking" (fn 56, p. 155).

5. Cf. H. Putnam, "The Meaning of 'Meaning'," Philosophical Papers, II, Mind, Language and reality (Cambridge: Cambridge University Press, 1975), pp. 215-71.

6. Cf. P.M. Churchland, "Eliminative Materialism and Propositional Attitudes," The Journal of Philosophy, 78, (1981): 67-90.

7. Cf. S. Stich, From Folk Psychology to Cognitive Science (Cambridge, Mass.: MIT Press, 1983) and H. Putnam, "Computational Psychology and Interpretation Theory," Philosophical Papers, III, Realism and Reason (Cambridge: Cambridge University Press).

8. For a sample, see J. Tomberlin (ed.) Philosophical Perspectives, 3, "Philosophy of Mind and Action Theory," (Atascadero: Riedgeview, 1989).

9. A distinction earlier espoused by McGinn in "The Structure of Content," A. Woodfield (ed.) Thought and Object (Oxford: Clarendon Press, 1982), pp. 206-58.

10. On the strong externalist view of perceptual content, "aetiology trumps aftermath" (65); on weak externalism, "aftermath trumps aetiology" (66).

11. See Putnam, "The Meaning of 'Meaning'," (op. cit., p. 224).