There is a concise but thought-provoking post over at the Philosophy of Brains blog by Gualtiero Piccinini here. ‘Psychosemantics’ refers to the project of explaining the intentional content of mental states in terms of non-intentional properties such as causal relations between head and world.
The problem with what Jerry Fodor refers to as ‘crude causal’ theories of content (CCT’s) is that they run up against the so-called disjunction problem: they aren’t sufficiently choosy about picking out the content constitutive properties from the ones that don’t matter. Thus a CCT might state a neural state type T represents some property P iff. tokens of P cause tokenings of T. So T means cat if it is reliably caused by tokens of catness.
The problem is this: CCT entails that any property at all which brings about T tokens is meant by it. So there can be no properties which cause its tokenings that it doesn’t mean. So CCT entails misrepresentation is impossible. But without misrepresentation we do not have representation.*
So psychosemantics becomes the game of constraining the indeterminacy of CCT type theories by heaping extra conditions on non-intentional properties. According to some (Dretske, Millikan) these are teleofunctional constraints. We amend CCT so that only properties T is evolved to pick out are meaning-constitutive.
Fodor’s ingenious alternative to this is assymmetric dependence theory. Where the mentalese/neuralese ‘cat’ means cat but can be tokened by the presence of bin bags, it must be because the causal link between ‘cat’ and cats constitutes its meaning in a way that the causal link with bin bags does not. Fodor’s solution is to say that the causal relations have different counterfactual properties. If ‘cat’ means cat but can be tokened by bin bags it is because I would not misidentify a bin bag as a cat but for the law that cats suffice to token ‘cat’. The same does not hold with ‘bin bags’. So there’s an asymmetry between the dependence of ‘cat’ tokenings on bin bags and its dependence on cats and this, so the story goes, suffices for ‘cat’ to mean cat or, at least, to not mean bin bag.
Piccinini notes that there is philosophical consensus that these and other emendations don’t work, but suggests they don’t fail so egregiously that we should give up on psychosemantics and opt for some anti-representationalist or anti-naturalistic alternative. This seems sensible to me. The achievement of psychosemantics is that it suggests ways of demoting meaning from the status of a transcendental mystery to that of a tough conceptual problem. Issues like disjunction and indeterminacy hardly warrant its abandonment.
For example, it seems reasonable to expect that content is usually just determinate enough to service the needs of biological systems: that there is no fact to the matter, say, about whether a frog’s visual system discriminates between the flies of its native marshes or the flying food pellets of the animal behaviourist’s lab.
As Dennett points out in Darwin’s Dangerous Idea, this is hardly a disaster for the naturalization project. It may be the kind of thing we should expect in a world in which meaning supervenes on biological and cultural processes. Moreover, indeterminacy is not all bad:
Unless there were ‘meaningless’ or ‘indeterminate’ variation in the triggering conditions of the various frogs’ eyes, there could be no raw material (blind variation) for selection for a new purpose to act upon. The indeterminacy that Fodor (and others) see as a flaw in Darwinian accounts of the evolution of meaning is actually a precondition for any such evolution . . . Meaning, like function, on which it so directly depends, is not something determinate at its birth. It arises not by saltation or special creation, but by a (typically gradual) shift of circumstances. (Dennett 1995, 408)
If the fly-detector were determinately a detector of flies then translating the frogs to their high-tech zoo would drastically alter the epistemic virtues of their representational states. The frogs would be mistakenly responding to the pellets as flies. If the fly-flicker was selective in the new environment there would surely come a point at which it ceased being determinately a fly flicker and acquired a new role of pellet flicker. But, Dennett claims, nature provides no cut-off point at which the mechanism suddenly assumes a new function. Hence, the old function must have been indeterminate all along. There is nothing in the frogs or their environment that makes it the case that they would suddently shift from being representers to misrepresenters of flies as a consequence of environmental change.
I don’t see why this indeterminacy, however constrained by the holistic inter-animation of sentences, shouldn’t percolate up to our linguistic and propositional thinking. Words, like evolved traits, can be turned to new uses, acquire new linkages and disciplinary contexts of use. ‘Mass’ was conceived by Newtonians as being invariant between inertial frames, whereas modern physics distinguishes between rest mass and relativistic mass (Field 1973). There may still be every reason for post-Einsteinian radical interpreter’s to say that the Newtonians had false or approximately true beliefs about ‘total mass’ (Ibid.) or were really referring to ‘proper’ or rest mass (Ibid., 466). It is not at all obvious that there need fact to the matter about which interpretation (or theory of meaning) is correct.
Some might argue that if this indeterminacy holds at all levels, then this implies that psychosemantics is a hopeless cause. We can never isolate a set of non-semantic properties sufficient for a creature that possesses them having proper mass beliefs, say, that wouldn’t preclude it having total mass beliefs. So a classic Nagelian reduction where semantic properties are linked to non-semantic properties via biconditional bridge laws seems to be ruled out. The best we can hope for, some might argue, is the supervenience (perhaps global) of mental/semantic properties on physical or non-semantic ones. Thus two worlds that are non-semantically alike must be semantically alike – e.g. with regard to the range of semantic theories that are warranted for any believers they contain. But, as everyone knows, supervenience-naturalism hardly merits that description. The supervenience of mental properties on physical properties is compatible with central state materialism, psycho-physical parallelism and epiphenomenalism, for example.
However, there may still be an indirect naturalistic explanation of how semantic properties supervene on non-semantic properties which falls short of reduction. At a first shot any mechanistic explanations of the discriminatory and inferential capacities that underwrite this behaviour throws light on the supervenience relation insofar as it tells us how the non-semantic properties of beings might allow them to exhibit the pattern recognition skills and reasoning capacities that merit their behaviour being regarded as ‘texts’ (candidates for interpretation).
More on indirect naturalization and indeterminacy to follow.
Dennett, Daniel (1995), Darwin’s Dangerous Idea, London Penguin.Field,
Harty (1973) ‘Theory Change and the Indeterminacy of Reference’, The Journal of Philosophy, Vol.. LXX, 15, pp. 462-481.Notes:
*Suppose I mistake a bin bag for a cat on a murky summer morning and up pops a T token in my head. CCT implies that the bin-bag property instance stands in a meaning-constitutive relation to T. Thus T cannot have meant cat and instead seems to represent some queer disjunctive property cat or bin-bag since instances of either suffice to make the relevant neural state or mentalese sentence light up.