Eliminative Materialism

Proposed Illustrative Parallels

The sort of conceptual revolution here contemplated is said to have numerous instances in our intellectual history. For example, in the 17th and 18th centuries, classical thermodynamics spoke systematically of a fluid substance called caloric, supposed to be responsible for all thermal phenomena. Caloric was said to flow from body to body, was constrained under pressure, participated in chemical reactions, and made steam engines go—it was thought. But despite its nontrivial explanatory and predictive virtues, caloric theory became plagued with explanatory and predictive failures, and it was eventually displaced, in the late 1800s, by statistical mechanics, a much superior theory that identified heat with the motions of submicroscopic molecules rather than with a macroscopic fluid substance. Caloric theory simply could not be squared with this new account of the reality underlying thermal phenomena. Caloric fluid was therefore eliminated from our scientific ontology and from our explanatory practices. The micromechanical framework simply took its place.

A second alleged parallel concerns the alchemical substance phlogiston, long supposed to be the principal element released into the atmosphere during the burning of any combustible substance or the rusting of any metal. This pre-Lavoisieran theory displayed, again, nontrivial explanatory virtues, but it was eventually displaced by the oxidation theory of combustion and rusting, a theory that said both processes involved not the release of something, but the ingestion of something: oxygen. Phlogiston was thus eliminated from our ontology entirely and was replaced by the various elements, compounds, and transformations of Lavoisier's new chemistry.

These cases exemplify the sort of conceptual revolution anticipated by the eliminative materialist, but a standard objection is that they are drawn from the theoretical stratosphere rather than from the realm of commonsense observables. Can we really assimilate the “manifest” states of our own consciousness to states that are plainly theoretical? The eliminativist replies that people at the time took caloric fluid flow to be eminently observable. Place a warm stone (or a snowball) in your hand: The inflow (or outflow) of caloric was manifest, to the touch, to anyone who possessed the concept. Even the evanescent phlogiston could be “seen” leaping skyward from any fire.

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