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Gold & Stoljar are right in their thesis but incomplete in not pointing out that there are many other arguments from cognate sciences suggesting that a radical eliminativist neuroreductionism is unlikely to be achieved. The radical neuron doctrine they criticize is only a hoped for dogma that cannot be verified, whereas a constrained monistic materialism (with only partial reductionism) is subject to immediate test by applying such criteria as combinatorial complexity and thermodynamic irreversibility.

Gold & Stoljar argue that there are two (often confused) neuron doctrines, one trivial and the other radical, with only the latter having the consequence that non-neuroscientific sciences of the mind will be discarded. They also attempt to show that there is no evidence supporting the radical doctrine. It is argued here that their dichotomy is artificial and misrepresents modern approaches to understanding the neuroscientific correlates of cognition and behavior.

I argue that the trivial neuron doctrine as characterized by Gold & Stoljar is not trivial; it appears to be inconsistent with property dualism as well as some forms of functionalism and externalism. I suggest that the problem is not so much with the particular way in which Gold & Stoljar draw the distinction as with the unruliness of the distinction itself. Their failure to see this may be why they misunderstand the views of the Churchlands.

As presently implemented, the neuron doctrine (ND) portrays the brain's neurons and chemical synapses as fundamental components in a computer-like switching circuit, supporting a view of brain = mind = computer. However, close examination reveals individual neurons to be far more complex than simple switches, with enormous capacity for intracellular information processing (e.g., in the internal cytoskeleton). Other poorly appreciated factors (gap junctions, apparent randomness, dendritic-dendritic processing, possible quantum computation, the living state) also suggest that the ND grossly oversimplifies neuronal functions. In the quest to understand consciousness, the presently implemented ND may throw out the baby with the bath water.

I argue that Gold & Stoljar's “trivial neuron doctrine” is not in fact trivial. Many familiar positions in the philosophy of mind run afoul of it, and it is unclear that even those whom Gold & Stoljar identify as adherents of the trivial neuron doctrine can be comfortably described as such.

Two notions of autonomy are distinguished. The respective denials that psychology is autonomous from neurobiology are neuron doctrines, moderate and radical. According to the moderate neuron doctrine, inter-disciplinary interaction need not aim at reduction. It is proposed that it is more plausible that there is slippage from the moderate to the radical neuron doctrine than that there is confusion between the radical neuron doctrine and the trivial version. What does it mean to say that the discipline of psychology is autonomous? Jerry Fodor (1998, p.!9) says that ‘a law or theory that figures in bona fide empirical explanations but that is not reducible to a law or theory of physics is ipso facto autonomous’. F-autonomy is irreducibility. The Churchlands mean more than this by autonomy; for them, to regard a discipline as autonomous is to ‘try to conduct the affairs of [that discipline] independently of the affairs of its immediate neighbours, both upward and downward in level’ (Churchland and Churchland, 1996, p.!220). We take it that this is not just a matter of pragmatic choices about conducting research with limited resources; rather, a discipline is autonomous when it is not governed or constrained by other disciplines. In this sense, C-autonomy is independence. On the face of it, the two doctrines are distinct and C-autonomy entails Fautonomy. Consider now the denial of autonomy in each case. Officially, the denial of F-autonomy about psychology is the claim that if there are laws or theories of a genuine empirical science of psychology then they are reducible to laws or theories of physics. We shall suppose that, en route to physics, the laws or theories of psychology would be reduced to laws or theories of neurobiology. This is the aspect of the denial of F-autonomy that we shall focus on: the denial of the autonomy of psychology from neurobiology. The denial of C-autonomy about psychology is the claim that psychological theories are constrained from above and below: ‘theories at different levels quite properly function as ongoing checks, balances, and inspirations for theories at adjacent levels, both up and down’ (1996, p.!221). In particular, the

According to Gold and Stoljar, one cannot both consistently be reductionist about psychoneural relations and invoke concepts developed in the psychological sciences. I deny the utility of their distinction between biological and cognitive neuroscience, suggesting that they construe biological neuroscience too rigidly and cognitive neuroscience too liberally. Then I reject their characterization of reductionism: reductions need not go down past neurobiology straight to physics, and cases of partial, local reduction are not neatly distinguishable from cases of mere implementation. Modifying the argument from unification-as-reduction, I defend a position weaker than the radical, but stronger than the trivial neuron doctrine. Gold and Stoljar (G&S) allow 'biological neuroscience' to include study of the function as well as the structure of neuronal ensembles (sec.2.1). But they think that invocations of function in actual neurobiological explanations already invoke non-biological concepts, so that explanations of causal mechanisms fulfilling those functions are not purely neurobiological. Because even an apparently physiological notion like the reflex is 'highly theoretical', G&S deny that it is a legitimate construct of physiology alone (n.40). It's as if the fact that neurophysiology, as Enc says, 'contains as an essential component a certain abstract level of description of the functional organization of the nervous system' (1983, p.298), automatically makes it a non-biological science! So the 'radical neuron doctrine' (RND) as defined is ludicrously strong. G&S’s purified definition, excluding all psychological, theoretical, or behavioral terms from neurobiology, allows only theorists who refuse to invoke concepts like classical conditioning, information, and representation consistently to propose RND. There may be some such among those who deny the utility of current concepts of representation, seeking instead to replace psychology with terms from dynamical systems theory (van Gelder 1995) or even quantum theory (Penrose 1994). G&S could persuasively argue that these attempts to unify cognitive science directly with physics, which are compatible with RND, do not have sufficient resources to explain mentality. But, surprisingly, they are not the targets. Instead, G&S implausibly interpret the Churchlands as supporters of RND. But neurocomputational models of learning and memory centrally invoke representations (P.S.Churchland and Sejnowski 1992, pp.141237). They are pitched ‘at a decidedly abstract level’: the two-pronged framework of transient, occurrent representations, and enduring, dispositional (distributed)

The element of truth in behaviorism tells us that some versions of a radical neuron doctrine must be false. However, the representational nature of many mental states implies that neuroscience may well bear on some topics traditionally addressed by philosophers of mind. An example is the individuation of belief states.

The complexity of modern neurobiology in even a comparatively restricted area such as use-dependent synaptic plasticity is underestimated by the authors. This leads them to reject a neurobiological model of learning as conceptually parasitic on the psychology of conditioning, on the basis of objections that are shown to be unsustainable. An argument is also advanced that neurobiologists hold an intermediate version of the neuron doctrine rather than a conflated one. In this version, neurobiologists believe that psychology will eventually be underpinned by neurobiology but are agnostic about the extent of upheaval that this will produce in psychology.

The trivial neuron doctrine (TND) holds that psychology merely depends on neurobiology. The radical neuron doctrine (RND) goes further and claims that psychology is superfluous in that neuroscience can “replace it.” Popular among RND notions of “replacement” is “reduction,” and in our commentary we challenge Gold & Stoljar (G&S) to make clear their distinction between merely depends on (TND) and is reducible to (RND). G&S give us a TND–RND distinction that is a distinction without a difference; a defensible TND–RND distinction must have a metaphysical basis. We suggest a denial of compositionalism as such a basis.

Gold & Stoljar's target article is important because it shows the limitations of neurobiological theories of the mind more powerfully than previous philosophical criticisms, especially those that focus on the subjective nature of experience and those that use considerations from philosophy of language to argue for the holism of the mental. They use less controversial assumptions and clearer arguments, the conclusions of which are applicable to the whole of neuroscience. Their conclusions can be applied to psychiatry to argue that, contrary to many researchers' assumptions, the approaches to both understanding and treating mental disorders must be interdisciplinary.

Gold & Stoljar's argument rejecting the “explanatory sufficiency” of the radical neuron doctrine depends on distinguishing it from the trivial neuron doctrine. This distinction depends on the thesis of “supervenience,” which depends on Hume's regularity theory of causation. In contrast, the radical neuron doctrine depends on a physical theory of causation, which denies the supervenience thesis. Insofar as the target article argues by drawing implications from the premise of Humean causation, whereas the radical doctrine depends on the competing premise of physical causation, the resulting critique of the neuron doctrine amounts largely to begging the question of causation.

Gold & Stoljar argue persuasively that there is presently not a good case for the “radical neuron doctrine.” There are strong reasons to believe that this doctrine is false. An analogy between psychology and economics strongly throws the radical neuron doctrine into doubt.