Individualism and computation

In this section I will consider several arguments for individualism that might be labelled "arguments from the Computational Theory of Mind(CTM)". According to such arguments, given the nature of

To show that tliis is not an isolated case Burge presents a whole battery of parallel cases. These cases feature the following terms "sofa", "contract", "brisket", "clavichord" and "red".

computation, scientific psychology's commitment to CTM entails that it is individualistic.

The first of these arguments is due to Fodor and is presented in his classic paper 'Methodological Solipsism Considered as a Research Strategy in Cognitive Psychology'. Methodological solipsism is an approach in psychology that considers the individual in isolation from her environment, attempting to describe her internal mental life in such a way that makes no assumptions about the nature of the external world. In ignoring the individual's environm ent and making no assumptions about its nature, such a psychology must describe and individuate psychological states in terms of properties that supervene on the individual's internal constitution. Assuming the truth of physicalism, a psychology that endorsed methodological solipsism would therefore individuate psychological states in terms of properties that supervene upon the intrinsic physical properties of the subjects that fell within its domain of inquiry.

Fodor argues that contem porary scientific psychology is methodologically solipsistic and thus, in virtue of its physicalist predilections, individuates in such a way as to respect the local supervenience of the psychological on the physical. His reasoning runs thus. Cognitive psychology is committed to CTM. Now computers only have access to the formal or syntactic properties of the symbols that they manipulate, being blind to their semantic properties (which are determined by features of the world external to the computer). Consequently, cognitive psychology is commited to the idea that mental processes only have access to the formal or syntactic properties of the symbols or representations that they manipulate; in other words it endorses the formality condition. This endorsement of the formality condition entails that the concern of

cognitive psychology is to 'study mental processes qua formal

operations on symbols' (p. 232), and thus that it will ignore the sem antic properties of m ental representations and states individuating such representations and states in terms of their formal or syntactic properties. In the case of physically realised computers, such properties supervene on their intrinsic physical constitution so that two physically identical computational systems will be formally or syntactically identical. In short, cognitive psychology, in studying and attem pting to characterise the

computational processes executed by and in the mind-brain, will consider the individual in isolation from the environment and will

individuate m ental states and representations form ally or

syntactically and thus individualistically.

This picture of the nature of cognitive psychology clearly conflicts with that developed in Chapter 2, and so should be rejected. The aim of cognitive psychology is to account for our intentionally characterised cognitive capacities. The subpersonal computational processing that underlies and supports such capacities is able to underlie and support them precisely because of the information processing problems that it solves or the information that it generates. Were it not for the information that the computational processes in my brain generated, I would not have the cognitive capacities that I in fact have. Consequently, a putative explanation of a cognitive capacity that merely characterised the computational processing qua formal symbol manipulation that underlay that capacity would not constitute a full explanation. A complete explanation must characterise the information generated by the computational processing (and thus attribute intentional content to the representations so manipulated) plus those facts about the world that enable the information to be generated in the way that it is. Therefore, cognitive psychology can hardly be methodologically solipsistic in the manner described by Fodor. First, it must attribute intentional content to our mental representations. And second, it must consider and appeal to facts about the environment external to the subject.

A second argument for the conclusion that the commitment of scientific psychology to CTM implies that it individuates individualistically rests on the idea that the intentional properties of mental representations are causally inert or epiphenomenal with respect to the phenomena that scientific psychology seeks to explain. Here is how the argument goes. Suppose an event el causes another event e2. Then el will have some property (or properties) in virtue of which it causes e2; such properties are causally responsible for el's causing e2. However, not all of el's properties will be causally relevant in this way; many will be causally inert or epiphenomenal with respect to e2. Consider an example. Edgar's diet causes him to develop a heart condition. His diet has many properties one of which

is the property of consisting of items purchased from Tesco's. It is not in virtue of its having this property that Edgar's diet causes him to develop a heart condition; with respect to that effect this property is causally inert or epiphenomenal. Rather, it is because it has the property of containing high levels of saturated fat that his diet causes him to develop a heart condition. An adequate causal explanation of Edgar's developing a heart condition must specify not just its cause (that is, his diet) but also the causally efficacious property of this cause (that is, its property of containing high levels of saturated fat). This point can be generalised: causal explanations, to be adequate, must specify not just the cause of the effect in question, but also the causally relevant property of that cause.

A consequence of CTM, with its endorsement of the formality condition, so the argum ent continues, is that the intentional properties of mental states and representations are causally inert with respect to the mental and behavioural effects that such states and representations cause. This is because computers only have access to the syntactic or formal properties of the symbols they manipulate, being blind to whatever intentional properties they have. Therefore,

intentional properties should not appear in psychological

explanations of behavioural and mental events. Such explanations should specify only the syntactic or formal properties of mental states and representations for it is they that are the causally efficacious properties. This result has bearings on the individuation question. For as intentional properties have no legitimate role in scientific psychological explanations, scientific psychology cannot legitimately individuate mental states in terms of such properties. It has no option other than to individuate mental states in terms of their syntactic properties, properties that are locally supervenient. Therefore scientific psychology, in virtue of its commitment to CTM and subsequent endorsem ent of the form ality condition, is individualistic.

Recently there has been much discussion of the question of the causal efficacy of content.^^ One popular way of responding to the

Much of ihis discussion concerns itself not so much with the consequences of CTM but rather with those of Davidson's anomalous monism. According to Davidson (1970): (i) causation is a relation between particular events; (ii) every token mental event is identical with some token physical event; and (iii) if an event e l causes another

threat of epiphenomenalism is to attempt to argue that, contrary to the epiphenomenalist's claim, intentional properties are not causally

i n e r t .48 Por the friend of CTM this would involve arguing (as do

Block (1990a) and Peacocke (1994)) that computers are sensitive to the semantic properties of the symbols they manipulate. In Chapter 2 I argued that computers are sensitive only to syntactic properties so I do not wish to follow this route. However, I think that all is not lost, for intentional properties are not required to be causally efficacious to have a legitimate role to play in scientific psychological explanation. This is another consequence of the nature of scientific psychology as I have described it. The causal inertness of content might well entail that intentional properties had no legitimate role to play in scientific psychological explanation if the aim of scientific psychology was to produce singular causal explanations of neurophysiologically realised m ental events and behaviour that was realised by bodily movements. But the fact that it aims to account for intentionally characterised cognitive capacities makes matters somewhat different. What is crucial about the causal processes that underlie and facilitate perception and cognition is that they generate relevant information. Ceteris paribus, if my visual system didn't generate the information

event e2, then el must have some property F, and e2 some property G such that it is a strict law that F-events cause G-events. As Davidson holds that the only strict laws are physical laws, this doctrine would seem to imply that the intentional properties of mental events are causally inert for whenever a mental event causes an effect it will have some physical property that is sufficient to determine that it produces that effect. For a discussion of this issue see Davidson (1993), Antony (1989) and Heil and Mele (1993).

In 'Making Mind Matter More' Fodor responds to the epiphenomenalist in this way. The version of the epiphenomenalist argument that he considers is the quite general one that all special science properties that are not identical to physical properties, being multiply realisable at the physical level, are epiphenomenal. He argues that a special science property F of an event e l is causally efficacious with respect to an effect event e2 that has special science property G if that causal chain is subsumed by the law that F's cause G's (this law need not be strict). He then argues that given the existence of intentional causal laws, intentional properties meet this condition and thus are not epiphenomenal. For a response see Segal and Sober (1990). For some other important contributions to the debate see: Jackson and Pettit (1988), Dretske (1988,1990), and Yablo (1992).

that it generates from the retinal images that it takes as input, then it would not enable me to perceive the world as I perceive it to be (or to find out about the world by means of vision). Hence an explanation of that capacity cannot ignore the information generated by the visual system's computational activity (and thus the content of the representations it manipulates). A purely syntactic account would leave it a complete mystery as to how the syntactic operations it described were able to support the target capacity and facilitate its exercise; it would leave out what, from the point of view of scientific psychology, was all important about those syntactic operations. All this will be the case even if the visual system is blind to the information carried by the representations that it manipulates; even if content is causally inert. So, in conclusion, the causal inertness of intentional properties does not entail individualism by debarring such properties from having any legitimate role to play in scientific psychological explanation.

A third argument for the conclusion that scientific psychology's commitment to CTM implies that it individuates individualistically has to do with implementation. The argument runs as follows. Higher level laws are implemented by lower level mechanisms. For a higher level law of the form "Fs cause Gs" to be implemented by the lower level mechanism that MFs cause MGs, it must be the case that the instantiation of the property F is sufficient for instantiation

of the property Mf and that the instantiation of the property MG is

sufficient for the instantiation of the property G. Now a scientific psychology committed to CTM holds that intentional laws are implemented by computational mechanisms. Given the general nature of the implementation relation, this implies both that there are computationally sufficient conditions for the instantiation of intentional properties, and that there are intentionally sufficient conditions for the instantiation of computational properties. A consequence of this is that computational mechanisms cannot implement broad intentional laws for it isn't generally the case that there are computationally sufficient conditions for the instantiation of broad intentional properties. (I believe that water is wet, yet being in the computational state that I am in isn't sufficient for having this belief, as my twin is computationally identical to me yet believes that twater is wet). As Fodor puts it, the assumption that intentional

properties are broad 'makes it very hard to see how there could be computationally sufficient conditions for their instantiation. How

could a process which, like computation, merely transforms one

symbol into another guarantee the causal relations between symbols and the world upon which . . . the [broad] meanings of symbols

depend?' {The Elm and the Expert, p .12). In short, computational

mechanisms can implement intentional laws only if those laws are narrow so that a scientific psychology that was both intentional and comm itted to CTM would have to be narrow on pain of inconsistency.49

My objection to the above argum ent is essentially that it misrepresents the nature of the implementation relation; there don't have to be lower level sufficient conditions for the instantiation of higher level properties in order for lower level mechanisms to im plem ent higher level laws. It is certainly true that for computational mechanisms to implement intentional laws there would have to be a close and systematic relationship between com putational properties on the one hand, and intentional properties on the other. But that relationship need not be one of coinstantiation (which is effectively how Fodor describes it). In fact, with respect to the case that concerns us, all that the implementation relation requires is the following:

49 In The Elm and the Expert Fodor represents ttiis argument as the fundamental