Guest Post: Is There a Real Distinction Between Reductionism and Eliminativism?

What follows is a guest post by a long-standing card-carrying member of the MavPhil commentariat, William the Nominalist.  He is eager to hear any thoughtful and pertinent comments you may have. 

The distinction between reductionism and eliminativism is widely recognised in the philosophy of mind and the philosophy of science. It also seems to be very clear. Here it is, as explained by William Ramsey.

Ontologically conservative theory change occurs when the entities and posits of the replaced theory are relocated, often with some degree of revision, in the replacing theory. For example, as our theory of light was gradually replaced by our understanding of electro-magnetic radiation, our conception of light was dramatically transformed as we recognized ways in which our old conception was mistaken or incomplete. Nevertheless, at no point did we come to say that there is really no such thing as light. Rather, light was eventually identified with a form of electro-magnetic radiation.

By contrast, our notion of demons did not come to find a new home in contemporary theories of mental disorder. There is nothing in the theories of schizophrenia, Tourette's Syndrome, neuro-pathology or any of the other modern explanations for bizarre behavior, that we can sensibly identify with malevolent spirits with supernatural powers. The notion of a demon is just too far removed from anything we now posit to explain behavior that was once explained by demonology. Consequently, the transition from demonology to modern accounts of this behavior was ontologically radical. We dropped demons from our current ontology, and came to realize that the notion is empty — it refers to nothing real.

But after a moment's reflection, I find it is not very clear at all. Why?

The problem is that pretty much every change of theory involves denying some entity or other. The ether theory of light, which was held until the late nineteenth century, depended on the existence of an ether, a hypothetical material or medium which carries light. So the electromagnetic theory of light requires the rejection of ether, and so is eliminativist with respect to ether (even though it is reductionist about light). More generally, every scientific theory requires unobservable entities postulated in order to explain certain observable phenomena. Since a change in theory typically involves denying the existence of the unobservables of the old theory, and replacing them with new ones, practically any change of scientific theory involves eliminativism of some kind. And so the distinction is meaningless, or at best arbitrary.

You object: surely the rejection of the ether theory does not involve the rejection of light? Yet modern psychology does involve the rejection of demons. I reply: this is an arbitrary case where we lost a name in common use - 'demons', which we could easily have kept. We could still today be referring to schizophrenia as 'demonic possession', while rejecting the assumption that a demon is an external supernatural entity that causes mental illness. After all, we still do not know the cause of schizophrenia - it is just a label for a set of observable symptoms, phenomena. All we know is that it is almost certainly not caused by supernatural intellegent beings.

Consider the case of 'humours'. We still talk about people being in a good or bad humour, about them being sanguine, or melancholy, or phlegmatic. As every historian of science knows, these terms originate in an ancient theory of mind, still held in the nineteenth century, according to which our mental states are affected by four basic substances: blood causing a sanguine temperament, black bile causing melancholy, and so on. The theory has long been rejected. But we continue using the terms. Why? They are good labels for certain easily recognisable behaviour patterns - phenomena - which we have kept. We simply reject the entities ('humours') postulated by the ancient theory. Or consider atoms. These are entities postulated to explain the observable differences in elements, and other phenomena. The word 'atom' comes from the Greek word for 'indivisible'. But in the late nineteenth century, it was discovered that atoms are in fact divisible. Did we drop the term 'atom'? Did we stop believing in atoms? No. We simply dropped the idea - an apparently essential idea deriving from the very definition of the term - that atoms are indivisible. They are useful for characterising physical phenomena in exactly the way that 'good humour' is a good way of characterising psychological phenomena. In the same way, I suggest, we might have held on to the term 'demonic possession', while rejecting the original explanation of its causes, just as we reject explanation of 'humour' in terms of blood and bile, but keep the term.

Note that Ramsey's remark that 'the notion of a demon is just too far removed from anything we now posit to explain behavior that once explained by demonology' equally applies to atoms. The notion of an 'indivisible particle' at the atomic level is too far removed from anything we now posit to explain physical and chemical change. Yet we continue to use the term 'atom'. And actually we do continue to use the term 'demons'. Someone asked me recently why I bothered to write philosophy. There is no reward, and the process is painful. Why do it? I replied 'demons'. He understood.

In summary, the distinction between 'eliminative' and 'reductive' theory change is arbitrary and unreal. Theory change of both types involves the rejection of some entity or another. The examples given to illustrate the distinction are arbitrary ones distinguishing the case of terms being dropped, from the case of their continued use under changed meaning or application. The distinction is at best one of linguistic practice, and refers to nothing real.

Comments

[Bill Vallicella]

William,

Thank your for your contribution. My knowledge of physics is limited, and so I could easily be wrong, but I don't think the following is quite accurate:

"The ether theory of light, which was held until the late nineteenth century, depended on the existence of an ether, a hypothetical material or medium which carries light. So the electromagnetic theory of light requires the rejection of ether . . ."

Until the time of the Michaelson-Morley experiment (Cleveland 1881)it was thought that light needed a medium of transmission (in the way that sound waves need air and ripples on a pond need water), a medium called 'ether.' Long story short, the M-M experiment turned up no evidence of ether. But I think it is wrong to say that the EM theory requires the rejection of ether. My understanding is taht the EM theory is consistent both with the acceptance and the rejection of ether.

Furthermore, I have never encountered until now the expression 'ether theory of light.' The hypothesis of the ether is not essential to the EM theory of light, although it is a natural assumption to make given that light is a wave phenomenon.

[Bill Vallicella]

>>Since a change in theory typically involves denying the existence of the unobservables of the old theory, and replacing them with new ones, practically any change of scientific theory involves eliminativism of some kind. And so the distinction is meaningless, or at best arbitrary.<<

You are referring to the distinction between elimination and reduction. I think you will agree that unobservables (e.g. ether)are theoretical posits. I suggest we distinguish between the elimination of unobservables/theoretical posts and the elimination of certain putative entities or states that are in some way observable.

For example, it seems to me that I am sometimes directly aware (via inner perception)of desires (hunger, thirst, sexual desire, etc.) But then Paul Churchland (noted eliminativist in the phil. of mind) comes along and says there are no desires. I say: that's a lunatic denial inasmuch as something plainly given is being denied. (As I may have said elsewhere: eliminativism is a philosophy of mind for those who have lost their minds.)

If desire were a theoretical posit (of 'folk pyschology') then Churchland's eliminativism would be less 'loony.' But it is not at all clear that desire is a posit of a theory. In fact, to me it is obvious that it is not.

In any case, it seems we ought to distnguish between the elimination of what are clearly theoretical posits and the elimination of observables.

With respect to states of desire (which, though not 3rd-person observable, are plainly 'observable' by the one who has them) the distinction between elimination and reduction seems fairly clear.

Eliminativist: There are no desires!
Reductionist: There are desires, but what they are are states of the brain or central nervious system!

It seems obvious that the sense of these two claims is different even if (as I would argue) reductionism in this case collapses into eliminativism.

[Account Deleted]

William,

Thanks for a very informative guest post.

Why can't we say this (I will be pithy!):

Suppose t1 is a term in some theory T (I allow common usage to count as theory for present purposes) taken to refer-in-T to entities of type e. The theory associates entities of type e with essential properties e1...en.

Reduction (roughly a la Nagel) is when (almost all) sentences in T involving t1 can be inferred from laws of another theory T* together with suitable bridge laws such that the laws of T* are committed to entities (whether called by the same name or not) of type e that feature most if not all of the essential properties e1...en and T* explains all the phenomena previously explained by T.

Elimination then can be a case where a theory T* replaces T so that (i) T* is not committed to entities of type e nor to any entities that feature the essential properties e1...en;
(ii) It is not required that T* explain *all* the phenomena previously explained by T.

Example of elimination: *Eliminative materialism* which rejects the existence of mental states such as beliefs including the essential properties associated with beliefs such as intentionality, rationality, even truth and falsity and replaces co-called folk psychology with some future neurophysiology theory which makes no reference to beliefs and dispenses with properties such as intentionality, rationality, truth and falsity.

[Bill Vallicella]

>>Note that Ramsey's remark that 'the notion of a demon is just too far removed from anything we now posit to explain behavior that once explained by demonology' equally applies to atoms. The notion of an 'indivisible particle' at the atomic level is too far removed from anything we now posit to explain physical and chemical change. Yet we continue to use the term 'atom'. <<

I don't think this is quite right. It turned out that what were called atoms (indivisibles) were divisible: they had 'subatomic' constituents: electrons, protons, and neutrons. But when the latter were first introduced fairly early in the 20th cent. were they not taken to be the 'real' atoms, the real indivisibles? So 'atom' is not like 'demon.' What were at first thought to be atoms turned out not to be atoms, strictly speaking, so the search for the true atoms went deeper. This was not a denial of atoms but an attempt at identifying the true atoms, the true ultimate building blocks of the physical world. But there was no parallel pursuit of the true demons. There occurred a denial of demons, not an attempt at identifying the true demons.

I hope my point is clear.

[Bill Vallicella]

Is sum, I am not convinced that there is no real distinction between E and R within the philosophy of science. And outside the phil. of science the distinction seems alive and well for the reason I gave above re: desire.

[Alfred Centauri]

Bill, you are indeed correct. AFAIK, it was the Special Theory of Relativity that rejected the need for an ether. Until then, the phase velocity of the EM waves predicted by Maxwell's equations was thought to be with respect to some absolute frame of reference, i.e., the ether. STR rejected the existence of an absolute frame of reference.

[Will Knowland]

Hugh Montefiore's book on the paranormal presents strong arguments that, in exceptional cases, the term 'demons' does in fact refer to something real. See 'The Paranormal: A Bishop Investigates' (Up Front Publishing, 2002), especially the appendix on contemporary philosophy of mind, which debunks Dennett, Dawkins and other bright young things.

[William]

Peter >>Example of elimination: *Eliminative materialism* which rejects the existence of mental states such as beliefs including the essential properties associated with beliefs such as intentionality, rationality, even truth and falsity and replaces co-called folk psychology with some future neurophysiology theory which makes no reference to beliefs and dispenses with properties such as intentionality, rationality, truth and falsity.

I did not understand the first part of your post, Peter. On the second part quoted above, depends on their being a meaningful distinction between the 'essential' and the 'accidental'. If 'belief' simply denotes 'whatever underlies belief-behaviour', then why should there be any 'essential properties' associated with belief. E.g. we could reject the idea of 'intentionality' as a mere accident of whatever-explains-belief-phenomena, while retaining the word 'belief'.

A neighbour's cat comes into our garden often and displays characteristics symptomatic of 'belief'. E.g. she sits fixated on the garden table looking for signs of movement in the compost heap. (Should there be scare quotes around 'looking for'?). Occasionally she pounces and catches a mouse. So it seems reasonable to say the cat believes there are mice living in the compost heap. Or some cat-like mental state that is similar to belief. We might disagree about the explanation of this behaviour (I'm not a cat psychologist). But we can't be eliminativist about the behaviour itself. I see it every day in the garden. And we could reasonably describe the behaviour as involving 'belief', whatever its explanation.

[William]

Bill >>I hope my point is clear.

It certainly was, but I think it missed the point. My point was about the question of whether we drop a term for some postulated entity, and when we keep it (but modify its application in some way). You might argue that when the term signifies some essential attribute, and when the new theory shows that there are no things possessing this 'essence', then we drop the term (and that we keep the term when the rejected attributes are 'accidental'). The 'atom' example suggests this is not so. We kept the the term 'atom' even though its original meaning involved indivisibility. We kept a term which means 'fundamental particle' for a particle that is not fundamental. Similarly in the case of 'humour', which means a specific mood-determining substance. This idea was once apparently essential to our understanding of the term, and we should have dropped the term together with the idea. But we kept the term nonetheless.

Similarly, we could have kept the term 'demonic possession', dropping the idea that the possession is supernatural as though an 'accidental' to the possession, even though supernaturalness seems to be essental to demonology.

The problem is that we have a specific phenomenon P, and we have a specific unobservable substrate postulated for the phenomenon. The substrate is always going to remain under the description 'cause of P' or 'reason for P'. Thus we can keep any term that we used before our change of theory, while changing our assumptions about what attributes the substrate possesses. So, if 'demonic possession' simply means whatever underlies the behaviour associated with schizophrenia, it is OK to keep the term, even if the change of theory requires we drop the idea of demonic possession being supernaturally caused (this might also change our idea of what 'demon' means also - Wittgenstein clearly was possessed by demons in some sense).

And yes it was of course the Michelson-Morley experiment which proved there is no light-carrying medium, just testing!

>>But then Paul Churchland (noted eliminativist in the phil. of mind) comes along and says there are no desires. I say: that's a lunatic denial inasmuch as something plainly given is being denied.

If Churchland is denying observable behaviour, then that is a different case than the one I have been discussing.

[William]

PS I discuss whether Hume is an eliminativist here:

http://ocham.blogspot.com/2010/08/is-hume-eliminativist-about-objects.html

[William]

PS: I've just noticed this series of posts here http://maverickphilosopher.typepad.com/maverick_philosopher/eliminative-materialism which I missed first time round. These mention the theory that folk psychology involves a theory (this first theory is called the 'theory theory'), together with the position that the folk theory of 'belief' involves certain 'essential' characteristics:

1. There are various causal properties of beliefs. They are are caused in certain circumstances, they interact with other cognitive states in various ways, and come to generate various sorts of behavior, depending on the agent's other desires and mental states.
2. Beliefs have intentionality; that is, they each express a proposition or are about a particular state of affairs. http://plato.stanford.edu/entries/materialism-eliminative/#ConEliMat

Eliminative materialism is supposed to be the outright denial of any entity with such features. Because (according to the theory-theory) these features are essential, i.e. it is part of the definition of the term 'belief' that belief involves at least these two features, just as 'rational' and 'animal' are part of the definition of 'man', any denial of these features amounts to the denial of belief. We could no more admit a belief that had no intentionality than we could admit a human being who was not an animal.

I reply: the theory-theory is false. There is nothing essential about the term 'belief' except that it signifies a state that underlying certain behaviours. We could easily imagine a time when we have dropped the idea that belief involves intentionality (which is a technical and difficult idea), but still call it 'belief'. Just as we dropped using the term 'good humour' to signify a mood-inducing substance, but kept it to signify a certain state with certain behavioural characteristics.

There is no radical distinction between eliminative and reductivist change in theory. It is just an arbitrary matter of whether we choose to continue with, or drop the use of certain terms like 'belief', 'light', 'humour', 'atom' and so on. It is a question of linguistic use alone, and involves nothing real.

[T. Hanson]

I am beginning to wonder whether eliminativism even makes sense. So far I have not seen a clear example of eliminativism except for the Churchland's which I agree with Bill is nutty. Perhaps this says something about the coherence of eliminativism. Examples discussed so far in the order of explanandum and explanans:

Insanity - Demons
Causality - necessary connection
light - ether
Personality/mood - humours
lightning - Zeus' anger (my own example)

In all the cases of revision, the explanandum is just eliminated in favor of another, or replaced (reduced). The explanandum is not eliminated. The Churchland's address:

Beliefs/sensations - mysterious intentional objects.

But they want to do away with the explanandum as well as the explanans. Is eliminativism defined as the doing away with the explanandum?

Or is elimininativism defined by retaining the explanandum and replacing explanans1 with explanans2, while maintaining that explanans1 does not exist? For example, in the case of insanity, everyone agrees insanity exists, but demons are replaced by other causes, and demons are eliminated as not existing.

On the other hand, scurvy was once explained as an effect of putrid air, but this was replaced by vitamin C deficiency. Putrid air still exists in contrast to the elimination of demons.

So there seem to be three kinds of revisionism in descending order of radicality:

1. Retaining the explanandum and replacing explanans1 with explanans2 while maintaining the objects posited in explanans1 still exist (putrid air).

2. Retaining the explanandum and replacing explanans1 with explanans2 while maintaining the objects posited in explanans1 do not exist (demons).

3. Eliminating the explanandum altogether (Churchlands).

3 is clearly eliminativism, but it is looney. Can anyone give an example of eliminativism in this sense which is not looney?

Is 2 eliminativism or merely reductionism? William seems to think this is (putative) eliminativism but I don't see why since it retains the existence of the explanandum, though it eliminates explanans1 altogether.

Are 2 and 3 being conflated in this discussion?

1 seems seems to be clearly reductionism.

[T. Hanson]

Oh, big typo!

When I said below my list of examples:

"In all the cases of revision, the explanandum is just eliminated in favor of another,"

I meant "In all the cases of revision, the EXPLANANS is just eliminated in favor of another,"

[bob koepp]

Paul Churchland took at least some inspiration from the history of chemistry, in particular, the elimination of phlogiston as an explanation of what we now view as oxidative phenomena. While this might be a fine example of elimination, his generalization to the mental sphere seems to many to be inapt (maybe even inept). But reductionism and eliminationism are distinct programs.

[T. Hanson]

The elimination of phlogiston would fit 2 in my scheme above. The explanandum - combustion/rusting - is not eliminated. Phlogiston is merely replaced by oxidation as the explanans. In the case of the Churchlands, as I understand them, the explanandum - mental states -are eliminated. There are just no such things to be explained and we should change our language to neurology-speak accordingly. So, the phlogiston example is not an example of Churchland-like eliminativism. The phlogiston example is more like the identity theory of the mind. There are mental states (the explanandum is preserved) but these are really brain states (mysterious intentional entities replaced by neurons, etc.)

[William]

>>Is 2 eliminativism or merely reductionism? William seems to think this is (putative) eliminativism

Not quite. In every theory change an entity (under some description) is eliminated. In your case 1, scurvy-caused-by-putrid air, or 'the causing of scurvy by putrid air' is what is eliminated.

In case 2, it is supernatural causation that is eliminated. Demons don't have to be eliminated, so long as we drop the idea that demons are supernatural in origin. Imagine a world where all mental illness is said to be caused by 'demons', but where 'demons' have a perfectly scientific explanation. Just as 'good humour' was reclaimed.

As you say, the explanandum cannot always be eliminated. Are we reading Churchland the right way? Where does he say this?

[William]

>>Paul Churchland took at least some inspiration from the history of chemistry, in particular, the elimination of phlogiston as an explanation of what we now view as oxidative phenomena. While this might be a fine example of elimination, his generalization to the mental sphere seems to many to be inapt (maybe even inept). But reductionism and eliminationism are distinct programs.

How are they distinct? As I have argued, something has to be eliminated in reductionism as well, under some description. The only difference is that in eliminativism, a term in common use is dropped. In 'reductionism' the term is kept, but under the elimination of the connoted entities. As I say above, imagine a world where the term 'demons' was kept, but the supernatural connotation was eliminated from its meaning, as a mere accidental feature of demonic possession. Then what was apparently eliminativist, becomes reductionist. But only by a linguistic sleight-of-hand. I expect the same could be done for 'phlogiston'. After all, it was done for 'electron' - where the difficulty was solved by electrons having a negative charge.

[William]

I looked up phlogiston and electron and I think I am right. It was orginally thought that current moved from the 'positive' pole to the 'negative' pole. And it was originally thought that on burning, flammable objects release 'phlogiston'.

Then it was discovered that current actually moves from the negative to the positive pole, in the opposite direction than originally thought. Similarly, it was discovered that flammable objects acquire oxygen, rather than release phlogiston. In the case of the electron, we kept the idea of 'positive' charge, by giving the electron a negative charge. So the theory is 'reductionist'. But rather than a similar manoeuvre with phlogiston, we dropped the term altogether. Thus 'eliminative'.

But all that was dropped was the term, rather than change its meaning. The distinction is purely linguistic, and not real, AFAICS.

[Alfred Centauri]

William wrote: "Then it was discovered that current actually moves from the negative to the positive pole,"

(sigh) As an EE, I cannot let this go without comment.

Current is a flow of electric charge. Electric current doesn't move or flow, electric charge does.

Moreover, since electric charge comes in two "flavors", a convention must be chosen for the direction since an electric current can be due to a flow of positive charge, a flow of negative charge, or some combination.

The convention (thus "conventional current") is that the direction of electric current is the direction of positive charge flow, i.e., protons flowing to the right give an electric current to the right, electrons flowing to the left give a current to the right.

Is this all academic? No. While it is true that current in metals is essentially all due to the flow of electrons, electric current in, for example, a battery or a plasma, may be due to the flow of protons, electrons, and both positively and negatively charged ions.

In other words, *an* electric current may be composed of a number of electrically charged entities flowing in opposite directions.

There, I feel much better now.

[bob koepp]

William - You asked how reductionism and eliminativism are distinct. Phlogiston provides an example of elimination without reduction, but since there seems to be some confusion on that score, let's take the opposite tack and point to a reduction that doesn't involve any elimination. The most frequently cited example of successful theoretical reduction is the reduction of phenomenological heat to mean kinetic energy. All the theoretical work done by the concept 'heat' is done instead using the reducing concept. It is often noted that if this reduction is successful, the term 'heat' is "in principle" eliminable from scientific discourse. But this "in principle" claim is not at all the same as saying there is no heat, or that heat was simply an imagined thing. Quite the opposite -- it grounds the notion of heat in fundamental physical theory.

[bob koepp]

Temperature -- not heat. My apologies to all.

[T. Hanson]

Bob Koepp said:

"let's take the opposite tack and point to a reduction that doesn't involve any elimination."

Temperature in the caloric theory of heat was explained by the density of caloric.

So, didn't mean kinetic energy eliminate density of caloric?

[T. Hanson]

The Stanford Encyclopedia of Philosophy article by William Ramsey addresses the issue to some degree.

http://plato.stanford.edu/entries/materialism-eliminative/

For what it is worth Quine thought there was no real distinction:

“Some may therefore find comfort in reflecting that the distinction between an eliminative and an explicative physicalism is unreal,” (Word and Oject, p. 265).

William asks, "Are we reading Churchland the right way? Where does he say this?"

The Churchland's don't want to say, for example, that pain, = the stimulation of c-fibers. That is identity theory. They say there are no pains, only the stimulation of c-fibers. So they are denying the existence of what is the explanandum in identity theory - pain (and by extrapolation they deny the existence of Mind which is the explanandum in the philosophy of mind) This seems to be doing something different from (and more extreme and incoherent than) the other examples of alledged eliminativism that have been mentioned in which one explanans is merely replaced by another. This is why if you listen to the Churchlands explain their view they often say things that sound a lot like identity theory, just like van Inwagen says you cannot establish an identity between a singular and plural term (his eliminativist move) but also does just that when he says walls are just bricks arranged wall-wise (his identity theorist move).

[William]

Bob: >>The most frequently cited example of successful theoretical reduction is the reduction of phenomenological heat [temperature?] to mean kinetic energy.

My arguments have obviously not been very clear :( As I was saying, all theory change invovles elimination *under some description*. Assume we have rejected the theory that 'phenomenological heat' is some non-mental spiritual substance. In that case, we have eliminated some purported non-material entity or substance. So reductionism always involves eliminativism, and there is no real distinction, apart from a linguistic one.

Does that make sense?

[William]

Hanson: >>The Churchland's don't want to say, for example, that pain, = the stimulation of c-fibers. That is identity theory. They say there are no pains, only the stimulation of c-fibers.

But what does 'pain' mean here? What if I use the word 'pain' to denote the stimulation of c-fibers? There is nothing to stop me defining a word as I like, in which case (in the sense I am using the word 'pain') the identity above is true. You object: the word 'pain' is actually used in a different sense. In the sense in which it means some non-material entity or substance or state, that could never be identical with a material state such as the stimulation of c-fibers, the identity is false.

I reply: exactly the same is true of the reductionist account. The reductionist who says that pain = the stimulation of c-fibers is clearly denying, by implication, the existence of some non-material mental state corresponding to 'pain'. Any theory change involves the elimination of some entity *under some description*. There is no essential difference between reductionism and eliminativism. The reductionist redefines a term and asserts an identity. The eliminativist insists on the original meaning of the term, and rejects the identity. Neither is really saying anything essentially different.

>>They [Churchlands] say there are no pains, only the stimulation of c-fibers.

And so does the reductionist, in the sense that the Churchlands are using the term 'pain' (meaning some non-material state). The reductionist says that there are pains, but using the term in a different sense (namely, meaning some material state).

[William]

Bob>>Current is a flow of electric charge. Electric current doesn't move or flow, electric charge does.

If current = flow of electric charge, and electric charge moves, then it logically follows that current moves.

[William]

>>If current = flow of electric charge, and electric charge moves, then it logically follows that current moves.

Sorry, I see your point. Saying that 'current moves' is like saying 'the flow of electric charge moves'. Was that your point?

[a.v.]

this is my impression...
Eliminativism is just the denial of the occurence of the explanandum. e.g.:
- There are no angels, so there is no reason to question about the sex of the angels
- There is no causal relation, so there is no reason to wonder if there is a first cause
- There is no mind, so there is no reason to question about intentionality or normativity
It's a way to refuse to account for something, because the entities presupposed by the question
are not given.
While reductionism accepts the explanatory challenge, so it maintains the explanandum, assumes the entities presupposed as given, but then it tries to replace the explanans A with the explanans B.
In short the distinction is relative to what we question and whether we accept to assume the explanatory challenge or not

[William]

It might help to clarify my point that all theory change involves the rejection of some entity 'under some description'. I mean: it involves the denial that some description 'F' applies to anything. So for example if the reductionist asserts 'every mental state is a physical state', it follows that he is denying that the description 'non-physical mental state' applies to anything, thus denying the existence of any non-physical mental state. And so the reductionist is really an eliminativist about such states.

And in general, assuming that all reductionist claims can be expressed in the form 'Every A is B', we can convert this into the claim 'there is no A that is not B' which is negative existential, denying the existence of As that are non-B. So *every* reductionist claim is really eliminativist.

What about the eliminativist? For every apparently every reductionist claim of the form 'Every A is B' there is a corresponding eliminativist claim 'there are no As'. But of course the eliminativist is using the term 'A' in a different sense from the reductionist. As the eliminativist interprets 'A', its definition includes the description 'non-B', and so 'every A is B' is false, according to him. But this is mere equivocation. In reality they agree. The reductionist believes that every mental state is a physical state, where 'mental state' is defined as some physical state. The eliminativist believes that there are no mental states, where 'mental state' is defined in a way that includes the non-physical. There really is no difference in what they are saying. The problem is that they cannot agree on the definition of terms. So the distinction is linguistic, and not real.

[bob koepp]

William - At least we agree that your arguments have not been clear. I think your use of the terms 'theory change', 'reduction' and 'elimination' is different from how they are standardly understood in philosophy of science. For example, theory change can occur by the simple extension of a theory to include previously unexplained phenomena, involving neither the reduction of previous theoretical terms to a new basis nor the elimination/rejection of previous theoretical postulates. I suggest that you familiarize yourself with the literature on these topics.

[William]

>>William - At least we agree that your arguments have not been clear. I think your use of the terms 'theory change', 'reduction' and 'elimination' is different from how they are standardly understood in philosophy of science. For example, theory change can occur by the simple extension of a theory to include previously unexplained phenomena, involving neither the reduction of previous theoretical terms to a new basis nor the elimination/rejection of previous theoretical postulates. I suggest that you familiarize yourself with the literature on these topics.

OK, what if I use the term 'relevant theory change' instead? Meaning any change of theory that apparently involves either a reductive or eliminativist approach?

Do you accept my argument about ' the reduction of phenomenological heat [temperature?] to mean kinetic energy'? I argued that it is still eliminativist in respect of heat understood as a non-physical property. Did that argument make sense?

[William]

>> suggest that you familiarize yourself with the literature on these topics.

OK, by all means suggest some literature. I carefully read the SEP article about this http://plato.stanford.edu/entries/materialism-eliminative before I wrote the post above. I don't think I am using the terms 'eliminativist' and 'reductivist' in any different sense - except that I am arguing they are inherently unclear. Each of the examples given to illustrate the distinction collapses, as each can be interpreted in the opposite way.

[William]

Bob. The best way to avoid unclarity is to agree on definitions. Below are two definitions that I have adapted from reliable-ish sources. Are these correct? Is there anything you would add to either of them? Is there anything you would take away.

(*)Eliminative materialism is the theory that people's common-sense understanding of the mind (or folk psychology) is false and that certain classes of mental states that most people believe in do not exist.

(**)Reductive materialism (a.k.a identity theory of mind) is the theory that mental states are type-identical to physical states of the brain with which they are correlated.

[bob koepp]

William - I don't want to abuse our host's tolerance of discussions on his blog in which he is not actively participating, so this will be my last post.

1) No, I do not accept your argument about the reduction of temperature to mean kinetic energy. Nobody who participated in that historical episode ever viewed temperature as a non-physical property.

2) Since you already are aware of the Stanford Encyclopedia of Philosphy, I'll suggest you search the SEP using 'reductionism' and 'eliminativism' as the search terms, and peruse the resulting articles and references. Please note that eliminative materialism is just one flavor of eliminativism, but even here, it is different from reductionism (which is inherently ontologically conservative).

3) I simply do not understand your claim that "Each of the examples given to illustrate the distinction collapses, as each can be interpreted in the opposite way." The elimination of the phlogiston theory by the oxygen theory did not involve the reduction of phlogiston; and the reduction of temperature to mean kinetic energy did not eliminate temperature from the ontology of physics. Both of these involved substantive theoretical changes, not "mere" linguistic changes.

4) The definition you proffer for EM is OK. The definitin for RM might be OK, depending on whether the "reduction" is taken to be theoretical rather than "merely" ontological (in which case, we'd be dealing with claims about token-identity rather than type-identity). But these definitions will not help to support your thesis that "*every* reductionist claim is really eliminativist." If mental states are type- (or token-) identical to physical states that exist, then the mental states in question also exist. That's how identity works.

[T. Hanson]

William, I disagree with Bob that you have been unclear. I think you have been clear from the start and think you may be right. If the term "pain," to use my example, continued in use as designation of neural activity, then the Churchlands, for example, would have turned out to be identity theorists and reductionists after all. If the term just disappeared, they would turn out to be eliminativists.
And this is a mere historical accident. My points is that there seems to be something else going on here. But I will leave that tack for now.

I guess what the Churchlands are depends on what happens in the future - whether the term survives, redefined, in the future. Or does it? Perhaps an essential feature of an eliminativist is that they actively push the reformation of language to purge the offending terms, while the reductionist is content with retaining the term and merely redefining it. Then the distinction would not be an historical accident, but a feature of the views themselves.

[William]

@Bob - I think Bill will be tolerant in light of the fact this is a guest post (by me).

Bob >>No, I do not accept your argument about the reduction of temperature to mean kinetic energy. Nobody who participated in that historical episode ever viewed temperature as a non-physical property.

Then it was confusing of you to talk about "the reduction of phenomenological heat to mean kinetic energy". The word "phenomenological" connotes the mental and the subjective in a way that 'phenomenon' does not.

Bob>>But these definitions will not help to support your thesis that "*every* reductionist claim is really eliminativist." If mental states are type- (or token-) identical to physical states that exist, then the mental states in question also exist. That's how identity works.

But then how would it be reductionist? Reductionism is not merely the assertion of identity. E.g. if I assert that Shakespeare was really the Earl of Oxford I am not being a reductionist. But if I assert that mental states are physical states, I am implicitly, perhaps explicitly, denying that mental states could be non-physical.

Hanson>>I guess what the Churchlands are depends on what happens in the future - whether the term survives, redefined, in the future.

I found the original paper by Churchland on the web here. http://psych.dbourget.com/readings/churchland.pdf It's very clear and well-explained and perhaps I can persuade Bill to let me have a second post to review some of the issues discussed there. Recommended.

[Bill Vallicella]

Gentlemen,

I am Toleration Itself (at least within purely philosophical discussions), so carry on as long as you think it profitable.

[bob koepp]

OK, with the blessing of Bill V, I'll press on...

It is common practice in the sciences to refer to theories formulated entirely at the "observational" level as phenomenological theories, and quantities such as volume, pressure and temperature are counted as observables. And I was simply following that common practice. So, with the confusion about connotation cleared up, do you agree that the elimination of phlogiston from theoretical chemistry did not involve reduction? If not, to what was phlogiston reduced? It won't do to say "Oxygen," since the theoretically/explanatorily relevant properties attributed to phlogiston do not even approximate those attributed to oxygen.

You are right that "reductionism is not merely the assertion of identity." But if it's identity plus "something else", whatever the "something else" might be, the implications associated with the assertion of identity still hold. So, if the "reducing basis" is held to exist, so must the reduced term be held to exist (i.e., it is not eliminated from scientific ontology).

Often, as in the case of temperature and mean kinetic energy, the "something else" is a redescription of the the thing being reduced in micro-structural terms. But there are also cases (particularly in psychology), where mental entities are reduced to and identified with dispositional properties that apply at the molar level. Rylean logical behaviorism is a case in point. Note that while Ryle denies that mind is an immaterial substance, he does not deny that minds and mental events exist. In short, while he claims that his theory eliminates an immaterial substance from our ontology, he nowhere claims to have reduced the immaterial to the material. (IIRC, Ryle's method is called "semantic reduction", which of course is a very different animal than "micro-reduction.")