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).