On confusing reduction with elimination

This summary I wrote from an old post helps explain the relation between reduction and elimination, since that came up in a discussion here.

The Churchlands wrote an essay entitled “Intertheoretic Reduction: A Neuroscientist’s Field Guide,” in On the Contrary: Critical Essays 1987-1997 (Cambridge, MIT Press, 1998) in which they distinguish three types of intertheoretic reductions: conservative, reforming, and eliminiative. The reduction of temperature in a gas to the mean kinetic energy of the gas’s molecules was a conservative reduction, in that it doesn’t require us to reconceive temperature in any radical way in order to view it as the MKE of the molecules. The secondary qualities of temperature, how it feels, are not denied, they are simply pronounced to be the way we react to temperature rather than something in temperature itself. If the concept of temperature was essential to the meaning of our lives, this type of reduction would not threaten us in any way.

The second type is a reforming reduction, which shows that an earlier theory had significantly misconceived the phenomena it covered. Newtonian mass is replaced in relativity theory with mass relative to a frame of reference, but we were not just dead wrong when we used the concept of mass.

The most radical is an eliminative reduction. In this, the old idea is so wide of the mark that it is simply deleted by the new theory. No single has does the work of phlogiston, but phlogiston is replaced by a theory that distinguishes between oxygen, carbon monoxide, and carbon dioxide.

Reply to an old response from Doctor Logic

There was an important response from Doctor Logic a month or so back which requires a response.
On to your main argument...Science was free to analyze what was quantitatively analyzable through mechanistic analysis and treat everything else as mental.I think the distinction that was made was between the objective and the subjective, not between mind and matter. I wrote a long response about this, but I think I can summarize it very briefly.Science is about isolating properties of things from biases of observers. That is, isolating properties are part of the thing itself rather than accidental side-effects of interactions with particular observers.An objective property of a system is a property that inheres in the system itself, independent of knowing anything about the external observer.I cannot say that music is objectively pleasant until I specify who is listening to it (i.e., put an observer in the system). So, I could say that Beethoven's 6th is objectively pleasant to me but not objectely pleasant in and of itself. Hence, pleasantness of music is subjective.However, by using instrumentation and external verifiers, we can show that sodium is objectively explosive in contact with water. We don't need to know anything about the experimenter to state this fact.Now, historically, it may be the case that some regarded the objective-subjective distinction as a mind-matter distinction (I don't know if it is or isn't the case). However, that's not necessary to the success of reductionist science. What's necessary is an objective-subjective distinction for systems.This would be my answer to your question "how did that work back then?"

VR: Here’s the problem I have with this. So long as we can include both subjective and objective features of reality as part of the furniture of the world, you can make a distinction between subject and objective features of the world that the early reductions required. The problem is that if reality is ultimately physical, then in the last analysis nothing is really subjective. In the last analysis subjective states are not subjective after all. What is ultimately real are physical states and combinations thereof. What is real are physical states and states that are logically entailed by the existence of those physical states. The subjective is expunged from orthodox physical descriptions, and there is no entailment from physical states to subjective states. Hence the “siphoning off” that was so essential for the early reductions will not work for mental states, and as a result the very thing that made a reduction of temperature to the mean kinetic energy of gases plausible makes the reduction of the mental to the physical implausible.