Monday, 20 June 2011

Recent developments for naturalising the mind

(This is now out in Current Opinion in Psychiatry.)

The philosophy of mind and psychiatry seem to be complementary disciplines investigating the same central issues. What is the nature of the mind, of the brain and body, and of their relation? And indeed much of the work of both disciplines is concerned with those central issues.

Over the last fifty years, philosophy has evolved a number of broad theories of the nature of the connection. They have ranged from the Churchlands’ eliminativist denial that there are mental states in favour merely of brain states [Churchland 1989], through forms of type-type reductionism such as type-type identity physicalism, which identifies types of mental state with types of physical state; behaviourism, which identifies types of mental state with types of behavioural state and functionalism, which identifies types of mental state with types of second order functional state [Fulford et al 2005: 613-66]. These last three approaches all aim to shed light on the mental in other terms (physical, behavioural and functional). They all face the challenge of avoiding, in Ned Block’s terms, chauvinism and liberalism (ruling out possible minds or allowing in too much) [Block 1980].

More modestly, Donald Davidson’s anomalous monism identifies each token mental event with a physical event (they are one and the same event) [Davidson 1980]. But what unites different mental tokens as instances of the same mental type (a shared kind of belief or sensation) is not given a physical reduction but rather explained through links to an irreducible rational pattern. Finally, there are positions which attempt no such reduction of the mental to the physical often emphasising the irreducibility of the qualitative aspects of mental lives – their qualia – or their intentionality or mental content.

One position in this debate which, whilst still not mainstream within straight philosophy of mind has enjoyed popularity within the philosophy of psychiatry is enactivism, discussed in two recent summaries [Drayson 2009, Potter 2010]. Its starting assumption is to stress the embodied, extended, embedded and enactive nature of the human mind and to use bodily interactions with the natural environment to account for features of the mind including both intentionality and qualitative aspects of experience. It contrasts with the still dominant orthodoxy of representationalist theories of mind which postulates mental representations characterised in information processing terms to carry (as ‘vehicles’) or encode mental content running on the brain as a kind of computer. Although varying in its explanatory aims, enactivist approaches share the assumption that the mind is extended beyond the boundaries of the skull. (One way in which enactivism cannot be easily be mapped onto the debate discussed in this review is that it concerns not the extra-cranial constitution of mental content but rather the extra-cranial mechanisms that carry or encode that content.)

I suspect that the popularity of enactivism in the philosophy of psychiatry is that it promises a translation between traditions. There has been continuity within European psychiatry between descriptive psychopathology and the philosophical tradition of phenomenology, exemplified in the work of Merleau Ponty, by a stress on embodiment. Work by Stanghellini and Fuchs are examples of this philosophically and phenomenologically informed approach to understanding psychopathology [Stanghellini 2004; Fuchs 2009]. In the UK and USA books by Ratcliffe and Gallagher also draw on phenomenology whilst also engaging with Anglo-American analytic philosophy [Ratcliffe 2008, Gallagher 2005]. Since enactivism shares with recent phenomenology assumptions about the role of the body but has been developed to address the agenda in Anglo-American analytic philosophy of mind, it promises to be a bridge between that and the problems of understanding psychopathology.

If the problem of understanding the relation between mind and body is made more difficult by the challenge of either accounting for (or somehow dismissing) the qualitative aspects of experience and its intentionality, some recent developments have challenged some assumptions about these aspects. In this review, I will focus on the latter issue starting first with accounts which attempt to locate mental states in nature by reducing them and then mentioning an alternative non-reductionist form of naturalism.

The orthodox approach to shedding light on the intentionality of mental states is remains representationalism of which Jerry Fodor’s early work was a very clear statement [Fodor 1987]. He combined the idea that the systematicity and compositionality of thought is explained by structured mental representations or symbols in a language of thought with a variant of a causal theory of how the symbols come to have worldly content or reference: the asymmetric dependence theory which is designed to explain how false thought or misrepresentation is so much as possible.

Fodor’s recent book, LOT 2: The Language of Thought Revisited, restates and develops this picture taking what he calls ‘pragmatism’ as the key target, the idea that thought’s key role is action rather than representation ‘So, one of the ways in which LOT 2 differs from LOT 1 is in the single-mindedness with which it identifies pragmatism as the enemy par excellence of Cartesian realism about mental states’ [Fodor 2008].

An alternative form of representationalism accounts for the possibility of falsity not merely through a complex causal mechanism, or what typically causes a representation, but through the idea of biological or proper function and thus what the representation is biologically designed to represent. This approach – teleosemantics – came to prominence through the work of Millikan who distinguishes between biologically mechanisms which produce representations, such as perceptual systems, and mechanisms which ‘consume’ them [Millikan 1984]. These might include mechanisms designed for predator evasion. It is the contribution that the representation makes to the consumer mechanism that determines its content: such as representing the presence of a predator.

This is an ongoing research programme [Macdonald and Papineau 2006]. But it has recently received a substantial and sustained criticism which threatens to undermine the key idea of mental representations deployed to explain the everyday intentionality of mental states.

Challenges to representationalism
In a summary of attempts to naturalise content through the idea of biological representations, Peter Godfrey-Smith expresses pessimism. ‘I doubt that teleosemantics, or any theory like it, will deliver the direct, reductive, puff-of-papal smoke solution that the 1980s literature envisaged’ [Godfrey-Smith 2006: 66]. His reason is that 30 years of philosophical theorising has delivered something in the same area but more basic.
‘One of the intuitions that has driven teleosemantics is the idea that rich biological concepts of function pick out a special kind of involvement relation between parts of organisms and their environments. Edging even closer to the semantic domain, there is a kind of specificity or directness that an evolved structure can have towards an environmental feature that figures in its selective history… But this relation is found in many cases that do not involve representation or anything close to it.’ [ibid: 60]

A more general critique of reductionist accounts of mental content is provided by William Ramsey in his book Representation Reconsidered [Ramsey 2007]. Ramsey points out that a lesson from the history of the philosophy of mind is that, as Dan Dennett noted, it is nearly always possible to describe physical processes in representational terms but it is never necessary. Just as one can avoid biological descriptions by describing biological systems in lower level physical and chemical terms, so representational terms need not be used. What then justifies the use of representational terms for complex systems? What is the explanatory benefit? Ramsey calls this the ‘job description challenge’. He argues that all the dominant approaches to explaining intentionality fail this test.

Take the case of a Venus fly trap which, according to Fred Dretske’s teleosemantic analysis, is supposed to have an internal trigger which responds to movement and thus signals the presence of insects [Dretske 1988]. Drekske says ‘there is every reason to think that this internal trigger was selected for its job because of what it indicated, because it told the plant what it needed to know.’ [ibid: 20]. But Ramsey asks why we need think of this in representational terms in addition to thinking that because of the lawlike connection between movement and plant closure plants with the trigger would be selected. ‘[T]here is no reason to think that structures recruited because their states have the property of being nomically dependent on some condition are also recruited because they carry information about that condition’ [Ramsey 2007: 135]. This mirrors the case of the firing pin in a gun which bridges the gap between pulling the trigger and firing the round. That lawlike connection is why the pin is part of the design. But there is no reason to think that the firing pin is a representation of anything.

Dan Hutto draws support from such criticisms of the attempt to locate representational content at sub-personal levels in his version of enactivism: ‘radical enactivism’ [Hutto 2010]. Arguing that other forms, such as Alva Noë’s, illicitly smuggle in sub-personal cognitive notions, his own builds in no assumption that content or meaning can play a role lower than the level of whole people [Noë 2004]. Nevertheless, he still wishes to appeal to some notion of primitive normative directedness: a kind of teleosemiotics which offers continuity between non-linguistic animals and humans. But how exactly the enactivist view of extended and embedded cognition contributes to making intentional content at the level of whole people less mysterious remains a matter of debate.

Challenges to interpretivism
Although reductionist naturalism is the dominant approach to meaning or content, there is another approach to locating meaning in nature which is to subscribe to a picture in which there are distinct and somewhat independent levels. Thus, in the tradition of Jaspers, whilst brain events are susceptible to scientific and lawlike explanation, mental events including the speech, action and experiences of whole people, are subject to understanding, which fits them into rational patterns.

This general approach has come under scrutiny in the philosophy of psychiatry, recently. Dominic Murphy, for example, has attempted to show how Marr’s threefold distinction between levels - computational theory, representation and algorithm, hardware implementation: [Marr 1982: 25] - can be applied to psychiatric explanation.

Murphy points out that Marr thinks of the levels in epistemic terms: as different ways of understanding the same system. One can determine its goals, the algorithm by which it determines those goals or the physical set up which implements that algorithm. But one might think of them as describing distinct forms of organisation in nature or distinct causal structures pitched at different ontological levels: ‘higher levels are made up of lower level things, and at each level things interact with each other rather than with things at lower levels’ [Murphy 2008: 103].

In psychiatry, however, neither of these pictures is quite right, according to Murphy, because there are different systems operating at different levels, unlike the epistemic view, but the different levels interact, unlike the latter view. Thus whilst Marr’s description of levels suggest that they are partly independent (the computational level constrains but does not determine the causal mechanisms that implements it), Murphy suggests that in psychiatry causes described at one level will have effects at another so that useful generalisations will cross levels.

John Campbell is more radical and argues that the very idea multi-level model of explanation in psychiatry results from a pre-Humean assumption about the intelligibility of relations tracked in causal explanation [Campbell 2008, 2009]. He gives, as an example, a discussion of thought insertion by Christopher Frith. Frith claims that whether or not inappropriate firings of dopamine neurons are found in subjects who experience thought insertion, that fact cannot be used to explain their experiences as it would shed no light on why that kind of symptom, rather than another, was produced by such firing. To shed light, Frith assumes, we need an account pitched at a particular level: in Frith’s case that of a sub-personal but still cognitive model of mechanisms supposedly responsible for thought insertion.

Campbell suggests that the assumption that there is a right level of explanation which clarifies things in the way Frith desires is the result of a pre-Humean view of causal explanation. Resisting the idea that the right kind of cause and effect have to be intelligibly, rather than merely brutely, related undercuts the motivation for the levels of explanation picture.

Just as we find it natural to expect there to be an intelligible mechanism underpinning material causal connections – even if this assumption lacks any genuine a priori justification – so Campbell also suggests that in the case of mental causation we expect there to be a rational connection between propositional attitudes. The rational link between two propositional attitudes is our paradigm of a mental causal mechanism. Again, however, whilst the idea that mental causation is underpinned by rational connections is natural and compelling, it lacks a priori justification.

Weakening the requirement on rationality also promises to ease the problem of account for delusions. If rationality is at the heart of interpretability and if that is at the heart of mentality, what are we to make of the apparently mental and apparently non-rational psychopathological experiences and states?

In her recent book Delusions and Other Irrational Beliefs, Lisa Bortolotti draws a key distinction between ‘conformity with’ and ‘subscription to’ norms of rationality [Bortolotti 2010]. If we assume that radical interpretation is tied to the first (as a methodological and thus a constitutive thesis) there are problems with real cases of inconsistency. If we retreat to subscription, we can defend actual inconsistency at the ground level but then, if subscription doesn’t imply in general conformity, it is no help in the ascription of mentality . So Bortolotti concludes that if there is no connection between subscription and conformity then the link between rationality and the ascription of mentality is lost. Further, drawing on empirical work on the reasoning of those not suffering from delusional states, Bortolotti argues that this is entirely plausible.

The question both of Campbell’s and Bortolotti’s criticism of the assumption of the role of rationality raise, however, is how light is shed on the mental in general without it. Placing utterances, actions and other states and experiences in a rational pattern seems to be a good way to shed light on what it is about them that counts as expressive of minds. Indeed, an extreme example of this wide view is Michael Thompson’s Life and Action which connects philosophy of mind exemplified in debate about what makes something an action with broader concepts of morally charged social practices and the nature of life itself [Thompson 2010]. In complete contrast to a reductionist focus on the micro-structure of our minds, Thompson looks to the broader context in which we live our life, act and pursue morally charged practices. But this leaves the challenge of how this broader canvas can be related back to psychiatry.

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