Shaffer presents a pair of objections to the identity theory of mind – the theory which says that mental events (and properties) are just brain events (and properties). The first objection is a critique of JJC Smart’s ‘topic-neutral’ analyses of mental events, and the second an epistemological objection against the identity theory in general.
Shaffer’s first critique is an attack on Smart’s ‘topic-neutral’ analyses, which were Smart’s way of getting around the possibility of mental events being brain events while still having irreducibly mental properties. If a mental state could be analyzed in ‘topic-neutral’ terms, or terms which categorized the event as a product of stimulus impingement yet did not reveal whether the event was physical or not, then an empirical investigation would be able to identity a physiological event with the topically-neutral mental event, and thus the properties of the event would end up being physical.
Shaffer has three problems with the topic-neutral strategy: for one thing, he does not think it is viable. He thinks that such an analysis of a mental state is incompletable, even in theory. But, even if it were completable, Shaffer thinks that the definition would be so full of complicated descriptions of physical processes that it would not actually reflect what people meant when they asserted the presence of mental events. The definition would not at all reflect the meaning of what we say when we describe mentality.
Shaffer also questions the appropriateness of categorizing the mental events in terms of stimulus impingement. Why suppose that the meaning of the event is captured by such terms? Shaffer thinks rather that meaning can be acquired via stimulus but that there is no good reason to suppose it can actually be characterized in terms of that stimulus. He gives an example: it might be the case that we can learn how an expression is learned (e.g., ‘Seeing stars’) without thereby knowing the meaning at all. And so too for the meaning in mental states: we might know all about the stimulus impingement surrounding a mental state without thereby being able to capture its full meaning in terms of those impingements.
Shaffer then presents an epistemological argument against the identity theory in general, couched in terms of noticing. Shaffer thinks that when a mental event occurs and we subsequently notice some property of it, we are not thereby noticing some property of our brain. The thing being noticed is not stimulus impingement or some state of the brain. Thus it follows that what is being noticed is a non-physical feature of the mental event, even if the event ends up being a physical one. Shaffer clarifies however that such non-physical properties might be reducible to physical terms in the sense that science may establish perfect correlation of mental events and neural events, thereby reducing psychological laws to neurological ones. The properties will still be non-physical, but will be fully explicable in terms of physical laws.
Argument One: Against Topic-Neutral Analyses
In order to be plausible, topic-neutral analyses need to fully capture the meaning of mental state terms, and they need to be completable.*
Topic-neutral analyses do not capture the full meaning of mental state terms, for they merely describe stimulus impingements related to such terms.
Topic-neutral analyses are not completable because indefinitely many factors would be needed to be state the causally sufficient conditions for a mental event’s occurrence.
Therefore, topic-neutral analyses are not completable and in any case do not capture the full meaning of mental state terms. [3 & 2]
Therefore, topic-neutral analyses of mental states are not plausible. [4,1]
Argument Two: Noticed, non-physical properties
If the identity theory true and mental events (and properties) were just brain events (and properties), then when one noticed a feature of a mental event, that feature would necessarily be physical.
Yet, when one notices a feature of a mental event, one is not noticing something physical such as, say, stimuli or some feature of one’s brain.
- Therefore, the identity theory is false. [2,1]
*This premise is an ‘enthymeme,’ or suppressed premise. All this means is that the premise is implicit to the argument and not explicitly mentioned by the author.