The place of mental content in the natural world

The fundamental worry of the naturalist is that intentional mental phenomena have no real place in the natural world and that the intentional and semantic properties routinely ascribed to our mental states in the course of psychological description and explanation have no reality. Alleviating this worry would involve showing that, and how:

(i) intentional mental phenomena occur in, and belong to, the natural world in broadly the same way in which, for example, biological, chemical, and geological phenomena do; and

(ii) the intentional and semantic properties of mental phenomena are as real as, and as real in broadly the same kind of way as biological, chemical and geological properties.

The purpose of engaging in the naturalisation project is to alleviate this worry. This point could do with much in the way of expansion and clarification.

By definition scientific intentional psychology is committed to the idea that some of our mental states have intentional and semantic properties; more specifically that some of our mental sates have semantic or intentional content. Moreover, its practitioners seek to produce explanations and theories in which appeals to such properties figure prom inently. Consequently, if there are any requirements or conditions that a property must satisfy in order to be

scientifically respectable - in order to have a legitimate role to play in the theories and explanations of a respectable science - then they m ust be satisfied by the semantic and intentional properties that figure in psychological theory and explanation.

An assumption that unites those who engage in the naturalisation project is that there is just such a condition or requirement in virtue, of the truth of the doctrine of physicalism and/or the commitment of science to that doctrine. U nderstood in the relevant sense, physicalism is the (perhaps vague) doctrine that our world is at bottom physical in nature; that it is at bottom nothing more than a very complex collection of physical particles organised hierarchically into aggregates that compose or constitute larger scale physical entities, states, events and processes, all of which behave in accord w ith the laws of physics. Thus physics is the most basic or fundamental science. However, according to the physicalist, this is not to say that physics is the only science or that physical properties are the only real properties. Rather, there are sciences other than physics - namely the special sciences - that appeal to properties that do not figure in the explanations, descriptions, predictions and. laws of physics. According to the physicalist the phenomena that the special sciences study and the properties that they appeal to are related to physical properties and phenomena in roughly the following way. Each and every special science entity, state, event or process is possessed by something (be it an entity, state event or process) that is physically composed, constituted or realised. And the relationship between special science properties, on the one hand, and physical properties, on the other, is that the former either reduce to or supervene on the latter so that the totality of physical facts fixes or determines the totality of special science facts. In other words the world couldn't be different at the special science level without being different at the physical level.

The upshot of all this is that the physicalist is committed to the idea that for any putative special science to be in good repute it must satisfy the following condition:

The phenomena that fall within its domain of enquiry must be physically composed, constituted or realised; the properties that its laws and explanations quantify over must be possessed by phenomena that are physically composed, constituted or realised;

and its properties m ust reduce to, or supervene upon, the physical.

So the question arises: does intentional psychology satisfy the above condition? It might be thought that a positive answer can quickly be established by arguing that intentional mental phenomena are

physically com posed, constituted or realised via being

neurophysiologically composed, constituted or realised and that intentional mental properties are possessed by phenomena that are at bottom clearly physical (be the bearers of such properties human individuals, brains, brain states, or something else along those lines). However this is far too swift, for it still remains to be shown that intentional properties either reduce to physical properties or supervene on the physical. A failure to indicate that (and how) lower level physical properties or facts fix, determine, or ground the intentional properties of mental states counts as a failure to indicate that (and how) intentional psychology manages to be a respectable, bona fide special science.^^

In short then, to engage in the naturalisation project is to attempt to indicate that (and how) physical properties or facts fix, determine, or ground the semantic and intentional properties that are attributed to our mental states in the course of psychological theorising and explanation. And Fodor's theory of content is an exercise in that project.

Of course one might attempt to naturalise any putative special science property, for they must all be related to the physical in the above described manner if they are to be scientifically respectable. But there is a widespread feeling within the philosophical community that there is an element of added urgency in the case of the intentional properties of mental states; that is why, at the beginning

Constitution/realisation by the physical doesn't entail supervenience on the physical as the following example indicates. Suppose that some physical objects have the property of being created by God. Such objects are physically constituted yet the property of being a physical object created by God does not supervene on the physical; rather it supervenes on factors outside the physical reahn. Consequently, intentional phenomena could be physically realised without it following that intentional properties are supervenient on the physical. Therefore, to establish that intentional properties are scientifically respectable one needs to do more than determine that intentional phenomena are physically realised or constituted.

of this section, I described naturalists as having a worry that intentional mental phenomena do not belong to the natural world and that intentional properties do not have the right sort of reality. Who knows how the naturalisation story goes w ith respect to geological, biological, and perhaps even chemical properties. But few would doubt that there is a story to be told, no matter how complex the details. Thus only an eccentric would harbour any doubts about the scientific respectability of geology, biology or chemistry. Alas, the same cannot be said of intentional psychology, for philosophers who doubt that there is a naturalisation story to be told with respect to intentional properties are literally queuing up to tell us the bad n e w s . T h u s we find Fodor making comments such as the following:

The worry about representation is above all that the semantic (and/or the intentional) will prove permanently recalcitrant to integration in the natural order; for example, that the sem antic/intentional properties of things will fail to supervene upon their physical properties. What is required to relieve the

worry is therefore, at a minimum, the framing of naturalistic

conditions for representation. ('Semantics Wisconsin Style' p 32) If the semantic and the intentional are real properties of things, it m ust be in virtue of their identity with (or maybe their

supervenience on?) properties that are themselves neither

intentional nor semantic. If aboutness is real, it must be really

something else.

Such philosophers make up a motley bunch. At one extreme there are those who, following Quine, believe that the semantic and intentional resist naturalisation as such properties constitute a closed circle and are happy to conclude: so much the worse for such properties and any descriptive and explanatory enterprise that trades in intentional talk. At another extreme there are those who, like McDowell and the later Putnam, think that the normative nature of meaning stands in the way of naturalisation, but that that is not to say that the intentional lacks reality or that all explanatory and descriptive enterprises that appeal to intentional properties thereby stand in a state of ill repute. Such philosophers object to what they see as the scientism of such philosophers as Fodor.

And, indeed, the deepest motivation for intentional irrealism derives from a certain ontological intuition; that there is no place for intentional categories in a physicalistic view of the world; that

the intentional can't be naturalised. {Psychosemantics p 97)

Given these worries there is a very real need to make some progress in the task of constructing a naturalistic theory of content. Once we have such a theory the mystery as to how our mental states could have semantic and intentional properties, and any doubts as to the possibility of a scientifically respectable intentional psychology, will evaporate.

If one is committed to the existence or the possibility of a scientific intentional psychology then one is thereby committed to the idea that the intentional properties that such a psychology appeals to in its theories and explanations are related to the physical in the very way that gives the naturalisation project its sense and importance. One cannot be a champion of scientific intentional psychology and deny that there is a naturalisation story to be told, a story that specifies just which aspects of the physical world fix or determine the intentional and semantic properties that that psychology ascribes to us and our mental states. Of course one is free to deny that there is, or could be, such a psychology. If one did this, one could consistently hold that there is neither a need for, nor a possibility of producing, a naturalistic theory of content. However, I don't find this position very attractive as it requires its advocate to hold either that contemporary cognitive psychology is not a legitimate science, or that its attributions of intentional properties to our internal states is not to be taken literally. Given that I have been arguing for a scientific cognitive psychology that, in the course of explaining our intentionally characterised cognitive capacities, makes literal and ineliminable attributions of intentional properties to some of our internal states, I am committed to there being a naturalisation story

I think that there is something distinctive about semantic and intentional properties that gives some prima facie or intuitive plausibility to the idea that they are not related to the physical in the way that bona fide special science properties are. For example, intentional states can be about things that are external to them, things with which they have had no causal contact, and, indeed, things that do not exist.

to be told with respect to those properties; a story that needs to be told in the course of constructing a complete and successful vindication of that psychology.

6.3 Reductionism

What form should a naturalistic theory of content take? What kind of theory should the naturalist be seeking? One thought is that the theory should attempt to reduce the intentional to the physical in the manner in which the property of being water reduces to that of being

H2O.101 Much of the opposition to the project of naturalising content

is based on the idea that to engage in that project is to thereby commit

oneself to the idea that the intentional reduces to the physical.^02 o f

course if intentional properties did reduce to physical properties it would be clear that (and how) intentional psychology could satisfy the requirements described in the previous section for being a respectable science. But is it really plausible that there is such a reductive relationship; that intentional properties have a non- intentional essence? Despite the well publicised examples of water, lightning, and heat, scientific investigation has uncovered few intertheoretic bridge laws and philosophers have proved even less successful in specifying convincing necessary and sufficient conditions for the application of even our most simple and familiar concepts. So we have every right to be sceptical about the prospects for naturalising intentional content by means of reduction.

The above quotes suggest that Fodor is seeking a reductionist theory. However, they are misleading, for, in keeping with his career-long opposition to the idea that the categories of the special sciences can (and must) reduce to those of physics, what he really seeks is a

For a helpful account of the nature of the reduction relation see Kim (1996) ch. 9. See, for example, Stich (1992) and Tye (1992), both of whom represent the naturalisation project as being one of specifying reductionist necessary and sufficient conditions for the application of intentional concepts. Both are sceptical about the possibility of reducing the intentional to the physical, but deny that any disastrous consequences follow from this, given the fact that special science properties rarely reduce to the physical and need not so reduce to be scientifically respectable. In other words, they object to what they see as the reductionist assumptions underlying and driving the naturalisation project.

sufficient condition for meaning (as opposed to a necessary and sufficient condition). It is consistent with the existence of such a sufficient condition that intentional and semantic properties can have many and varied sources; that no such property has a non- semantic and non-intentional essence. The idea is that it is possible that my cow thoughts are about cows (rather than something else or nothing at all) for one reason, that the states of my visual system represent what they represent for some other reason, and that Fang's thoughts are about food for yet a third reason. In other words, in each of these cases some feature of the physical world is responsible for, fixes or determines, the intentional properties of the mental state in question; but that feature might differ from case to case.

But why, one might wonder, must there be any such non-semantic, non-intentional, sufficient conditions? The answer has to do with the doctrine of physicalism. Physicalism doesn't require that higher- level, special science properties reduce to those of physics, but it does require that where there are no relations of reduction or identity there are relations of realisation and supervenience. In other words, at the very least, higher-level special science properties are physically realised and have physical supervenience bases so that whenever such a property is tokened in our world the tokening of that property is the product of, or is fixed or determined by, some lower level physical feature of the world such that the higher level property in question couldn't but have been tokened given that physical f e a t u r e . N o w the existence of such supervenience or realisation relations between higher-level special science properties and lower- level physical properties entails that associated with each special science property will be a battery of conditional statements each specifying a physical condition the satisfaction of which is sufficient for the tokening of the higher-level property in question. There may be infinitely many such physicalistic sufficient conditions associated with each higher-level property, each one specifying a distinctive way in which a tokening of that property can be generated. To deny of a higher-level non-physical property that there are any such

133 In this context we need not worry about the specific nature of the supervenience relation (e.g. "strong", "global", or whatever) implied by physicalism, or whether the notion of necessity implied by "couldn’t but have" is m etaphysical or nomological.

physicalistic sufficient conditions associated with it is either to deny that it is scientifically respectable or to reject the doctrine of physicalism.

What these considerations imply about intentional properties is the following. If there is to be a scientifically respectable intentional psychology then the intentional properties that figure in the explanations and theories of that psychology must have physical supervenience bases. Thus, associated with each of these properties there m ust be physicalistic sufficient conditions such that the satisfaction of their antecedents guarantees the tokening of the property in question. To deny that there are such sufficient conditions is either to deny the possibility of a scientific intentional psychology or to reject physicalism. Anyone who is committed to physicalism (a doctrine that I take to be uncontestable and fundam ental to the ideology of science) and to the reality or possibility of a scientific intentional psychology must accept that there are such physicalistic sufficient conditions for the tokening of intentional properties.

To attem pt to uncover physicalistic sufficient conditions for meaning is to engage in the naturalisation project without thereby committing oneself to any implausible reductionist thesis. Seen in this light I think that it is clear that the naturalisation project is not a misguided project, and that it is an especially important one in which to make progress given the widespread scepticism concerning the prospects for a respectable scientific intentional psychology. Once we have specified some appropriate sufficient conditions we will have indicated that intentional properties supervene on physical properties and removed the mystery as to how intentional facts could be determined or fixed by physical facts.^34

104 Michael Tye (1992) argues that intentional psychology is a respectable science, and in the course of doing so constructs an account of the relationship between psychology (and higher level sciences in general) and physics that is similar to my account. He advances a version of what he calls "naturalism" according to which:

The general relationship which obtains between higher level and lower level physical properties is one of realization . . . The realization relation is, at least in part, one of determination: the lower level property synchronically fixes the higher level one so that the tokening of the former at any time t necessitates the token of the latter at t but not conversely. . . The parallel between types and

But what is the nature of the required physicalistic conditions? In

Psychosemantics Fodor explicitly states that his theory is intended to specify a sufficient condition that is satisfied by our mental states. For example, he writes:

I want a naturalized theory of meaning; a theory that articulates,

in nonsemantic and nonintentional terms, sufficient conditions

for one bit of the world to he about (to express, represent, be true

of) another bit. I don't care . . . whether this theory holds for all

symbols or for all things that represent . . . I'm prepared, that is,