Eliminativism and Reductionism

One of Ian's comments on an earlier post of mine got me thinking about the distinction between theoretical elimination and theoretical reduction. This is a familiar distinction in the philosophy of mind, but it comes up in lots of different contexts.

In general, eliminativism (E) and reductionism (R) are reactions to a thesis (T) to the effect that "Things of kind X exist", where X is a description of the kind in question. Both E and R are denials of T, but they differ in an important respect. The eliminativist not only denies the existence of X-type things, but also rejects the propriety of talking as if X-type things existed. The reductionist, on the other hand, continues to affirm the propriety of talking as if the thesis were true while denying that there are any X-type things in the sense countenanced by the thesis. She accomplishes this by identifying a non-T substitute as the "real" referent of X. Here are some examples:

• Thesis: God (understood in a broadly classical sense) exists.
• Eliminativist: Such a being does not exist, nor should we say "God exists" because it cannot be affirmed without perpetuating falsehood and confusion.
• Reductionist: God as understood in the broadly classical sense does not exist, but "God exists" can properly be said because the descriptor "God" really refers to something else (e.g., the Cosmos, energy, the idea of a broadly classical God, etc.).
  

• Thesis: Cartesian souls exist - mental terms (e.g., "beliefs", "desires", etc.) refer to states that are strictly nonphysical.
• Eliminativist: There are no Cartesian souls or nonphysical states. We should not continue to talk as if there were mental states.
• Reductionist: There are no Cartesian souls, but it is okay to continue talking of mental states - we just have to realize that mental states are really just physical states.
  

The observation I want to make is that the eliminativist and reductionism agree on matters of substance. They concur that the thesis is false. Where they disagree is on matters of language. They disagree about the ethics of terminology, the propriety of speaking in certain ways. The eliminativist prefers to use language in much the same sense as the proponent of the thesis does. Hence, along with his denial of the thesis the eliminativist rejects the language used to formulate the thesis as false and misleading. The reductionist, on the other hand, doesn't want to let proponents of the thesis define how the key terms are to be used, and so she substitutes her own definitions. This allows her to preserve the verbal formula used in the affirmation of the thesis while gutting it of what she sees as objectionable commitments.

The debate between eliminativists and reductionists would seem to turn on prevailing or established usage. For example, with respect to the meaning of "God", the reductionist substitutes have little or no claim to capture the force of that word as it has actually been used in the Western theological tradition. This is just atheism in denial, not a redefinition of "theism" that is still worthy of the name. In contrast, the theoretical reduction of "heat" from traditional understandings of it as a manifestation of an element (fire) or a type of fluid (caloric fluid) to "average kinetic energy" marked a useful theoretical advance. The justification for continuing to use the word "heat" while changing its meaning lies in the broad commonality of the observational data that the respective theories were invoked to explain.

To some extent, whether a position should be called 'eliminativist' or 'reductionist' may be a matter of perspective. For example, in my ongoing dialogue with Ian, I affirm as an A-theorist that there are tensed facts. Ian, a B-theorist, also affirms the existence of tensed facts, but he defines them in accordance with his metaphysics. So he claims to be a reductionist and not an eliminativist with respect to tensed facts. From my perspective, however, Ian's "tensed facts" are trivial and uninteresting and the real metaphysical issue is whether there are tensed facts in the A-theorist's sense. So what he calls reductionism, I call eliminativism in denial.