Gold & Stoljar's attempt to disentangle the body-mind problem in time for the end of the decade of the brain deserves praise for its diligence and courage in moving onto the treacherous ground of interdisciplinary discourse. In making their point, they should not have stopped half-way: a more clearly defined experimental paradigm seems necessary to solve this exciting and substantial problem.

In reply to Wierzbicka's advocacy of semantic primitives we argue that talk of the semantic primitives (like to see) repeats the fallacies addressed in the target article at a higher level. In reply to Malcolm's plea for a Wittgensteinian grammar of colour words, we argue that he uses words like “we” and “us” too easily, falling into the trap of “silly relativism.” In reply to McManus's science of word counts, we reiterate the nineteenth-century criticism that this method is based on an illegitimate application of seemingly rigorous statistical methods.

Millikan (1998a) relies on the ability an organism may have to reidentify external objects. It is difficult to develop an account of how this might occur because the organism could make a mistake in the tokening of a concept; it could misidentify the external object. To sustain her nondescriptivism, Millikan's account of reidentification must make the link between concept and object arbitrary. However, to make mistakes possible, there must be a norm for the production of concepts. These two requirements seem to leave no room for a middle ground.

The target article approaches individual differences in terms of phenotypic differences developing through the interaction between a specific genetic make up and environmental variables. This interaction is proposed to be cooperative and oriented toward a progressive stabilisation of the trait. However, experimental data from animal studies indicate that environmental pressure promotes dramatic changes in phenotypic expression in mature organisms. Indeed, environmental constraint not only promotes the phenotypic expression of facilitated VTA-NAS DA transmission in genotype-resistant individuals; it also inhibits its expression in genetically prone individuals. This is in line with negative genotype-environment correlation revealed by behavior genetics.

The following discussion aims to illuminate further the way in which morphologically complex words are represented in the mental lexicon. It is argued that the dual-mechanism model can accommodate the linguistic and psycholinguistic evidence currently available, not only on German inflection (as pointed out in the target article) but also on other languages (as presented in several commentaries). Associative single-mechanism models of inflection, on the other hand, provide only partial accounts.

Neither of the explanations O'Brien & Opie offer to account for “subject unity” succeeds. Subject unity cannot arise from constructed personal narratives, because such narratives presuppose a prior unity of experience. Subject unity also cannot arise from projection of experiences to the same position in space, as reflection on pregnant women and the spatially deluded reveals.

In one of their arguments against the radical neuron doctrine, Gold & Stoljar (G&S) use the idea that, in certain situations, equivalent terms may not be substitutable into statements that regard properties of the objects to which the terms refer. This device allows G&S to refute the necessity of the conclusion that “the science of the mind equals the science of the brain” even though they take as a premise that the mind equals the brain. I argue, however, that this practice leaves the meaning of the “science of the mind” and the “science of the brain” indeterminate.

The basic postulate that consciousness arises from stable states of recurrent activity is shown to need considerable modification from our current knowledge of the neural networks of the brain. Some of these modifications are outlined.

Millikan's discussion of substance concepts in terms of their information-gathering role ignores the analyses of information-based perception and action developed within the tradition of ecological psychology. Her introduction and use without definition of key Gibsonian terms such as “affordance” and “direct perception” leaves those of us investigating such concepts uncertain of the extent to which she appreciates their theoretical importance. Due recognition of the realist account of categorical perception developed by J. J. Gibson would provide mutual benefit to modern externalist philosophy as well as to experimental psychology and to those investigating the ecological approach to perception–action.

Although a wide variety of questions were raised about different aspects of the target article, most of them fall into one of five categories each of which deals with a general question. These questions are (1) Is the radical neuron doctrine really radical? (2) Is the trivial neuron doctrine really trivial? (3) Were we sufficiently critical of the radical neuron doctrine? (4) Is there a distinction to be drawn at all between the two doctrines? and (5) How does our argument bear on related issues in the ontology of mind? Our replies to the objections and observations presented are organized around these five questions.

I focus on a number of issues arising from Depue & Collins's target article that require further consideration: (1) data that fail to confirm extraversion effects in positive incentive experiments; (2) the role of personality factors, other than extraversion, in dopamine agonism on positive mood states; (3) the role of extraversion in nonspecific arousal, indicating that extraversion may not be an homogeneous trait; and (4) the problem of identifying neurobiologically important traits from existing structural models of personality. I applaud the heuristic value of the model presented and suggest ways in which aspects of the model may be used to identify the personality traits associated with positive incentive motivation.

There are many ways of describing and explaining the properties of living systems; causal, functional, and reductive accounts are necessary but no one account has primacy. The history of biology as a discipline has given excessive authority to reductionism, which collapses higher level accounts, such as social or behavioural ones, into molecular ones. Such reductionism becomes crudely ideological when applied to the human condition, with its claims for genes “for” everything from sexual orientation to compulsive shopping. The current enthusiasm for genetics and ultra-Darwinist accounts, with their selfish-gene metaphors for living processes, misunderstand both the phenomena of development and the interactive role that DNA and the fluid genome play in the cellular orchestra. DNA is not a blueprint, and the four dimensions of life (three of space, one of time) cannot be read off from its one-dimensional strand. Both developmental and evolutionary processes are more than merely instructive or selective; the organism constructs itself, a process known as autopoiesis, through a lifeline trajectory. Because organisms are thermodynamically open systems, living processes are homeodynamic, not homeostatic. The self-organising membrane-bound and energy-utilising metabolic web of the cell must have evolved prior to so-called naked replicators. Evolution is constrained by physics, chemistry, and structure; not all change is powered by natural selection, and not all phenotypes are adaptive. Finally, therefore, living processes are radically indeterminate; like all other living organisms, but to an even greater degree, we make our own future, though in circumstances not of our own choosing.

Something of the relation of my work on substance concepts to Gibsonian theories of perception–action is discussed. What historical relations tie a particular substance concept to a particular substance is discussed.

We address two points in this commentary. First, we question the extent to which O'Brien & Opie have established that the classical approach is unable to support a viable vehicle theory of consciousness. Second, assuming that connectionism does have the resources to support a vehicle theory, we explore how the activity of the units of a PDP network might sum together to form phenomenal experience (PE).

Studies of human performance indicate that extraverts show enhanced motivation in relation to reward signals, but not in relation to safety signals under defensive conditions. When it occurs under defensive conditions, enhanced motivation may be related to neuroticism. While extraverts show some attentional skills consistent with frontal dopaminergic facilitation, other frontal capacities may be related to conscientiousness. These findings suggest that dopaminergic influences on response and attentional processes may contribute to additional personality dimensions such as neuroticism and conscientiousness.

O'Brien & Opie run into conceptual problems trying to equate stable patterns of neural activation with phenomenal experiences. They also seem to make a logical mistake in thinking that the brute association between stable neural patterns and phenomenal experiences implies that they are identical. In general, the authors do not provide us with a story as to why stable neural patterns constitute phenomenal experience.

We make two suggestions with regard to Depue & Collins's (D&C's) target article. First, regarding the functioning of MOC13, we provide data indicating that, contrary to D&C's apparent position, this structure is not necessary for instrumental conditioning. Second, we suggest that D&C's approach would be advanced by reference to formal computational theory, in particular the work of Grossberg. We suggest that an integration of Grossberg's and D&C's models can provide a more complete account of extraversion.

Lifelines mounts a vigorous attack on sociobiology on the utterly mistaken grounds that sociobiologists believe that genes single-handedly determine social behavior. The many previously published rebuttals to this pernicious criticism are conveniently ignored by the author.

The neurobiological mechanisms associated with affiliation, that Depue & Collins argue are a central component of extraversion are not specified in their model. In addition, only the involvement of the prefrontal cortex in extraversion is discussed, although recent evidence suggests that activity associated with additional cortical regions may be related to this trait. Finally, the assumption that neurobiological mechanisms underlie or play a causal, and therefore, more fundamental role than psychological constructs in the trait is challenged.

Metaphors have three important functions in scientific discourse: heuristic, rhetorical, and epistemic. I argue that, contrary to prevailing opinion, metaphors are indispensable components of scientific methodology as well as scientific communication. Insofar as the choice of metaphors reflects ideological commitments, all science is ideological. The philosophically vexed question is how to characterize the sense in which science is not merely ideological.