Reduction and Elimination in Philosophy and the Sciences

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Reduction Revisited: The Ontological Level, the Conceptual Level, and the Tenets of Physicalism — Markus Gole
The idea of a conceptual reduction is not a new one
and the following two examples underline its relevance for
a proper understanding of reduction. For instance, logical
behaviorists (e.g., Ryle 1949) explicitly state that all mental
expressions can be translated into, and thereby reduced
to, expressions about behavioral dispositions. Thus, the
logical behaviorist is some kind of an a priori physicalist in
the sense described above, because the mental concept
"pain" is translated into a statement about withdrawal behavior
resulting from tissue damaging stimuli. Once a conceptual
reduction has been accomplished, an ontological
reduction will follow. Kim (2005) makes a similar point with
his model of functional reduction. According to Kim, the
first step in a successful ontological reduction is to define
the mental property in question functionally, i.e., in terms of
the causal role it occupies. As Kim clearly says, that is a
matter of conceptual work and in terms of the present paper
it is a conceptual reduction carried out a priori. For
instance, the mental concept "pain" is translated into a
statement about pain and its role in avoiding bumping into
more tables in the future. The second step in Kim's model
is to find the realizer of the functionalized property, that is,
to find the property which fulfills to role of avoiding bumping
into more tables. The third and last step is an explanation
of how the property which fits the functional specification
does its job.
3. An Argument for Conceptual Reduction
Let us assume, in the spirit of physicalism, that pain has
been successfully reduced to a C-fiber stimulation on the
ontological level. Moreover, every C-fiber stimulation is
describable in purely physical concepts. Does it follow that
pain is describable in purely physical concepts as well? Let
us take a closer look:
(1) Pain = C-fiber stimulation.
(2) Every C-fiber stimulation is describable in
purely physical concepts.
(3) Ergo, every pain is describable in purely physical
concepts.
This argument claims that as a result of the type identity
statement "pain = C-fiber stimulation" and the descriptiveness
of every C-fiber stimulation in physical concepts, one
is entitled to conclude that also pain is describable in
physical concepts. The expression "C-fiber stimulation" in
premise (2) can be replaced by "pain" in virtue of their
identity established in premise (1). On what grounds could
this argument be refuted? One objection comes from the
proponents of a posteriori physicalism. A posteriori physicalists
acknowledge that a priori physicalists have to accept
that argument, and therefore, a conceptual reduction
follows from an ontological reduction, but only if a priori
physicalism is true. However, if a posteriori physicalism is
true, the argument is a non sequitur. (3) does not follow
from (1) and (2), because in order to describe pain, one
has to use the mental concept "pain". The reason for this is
the independence between mental and physical concepts.
Once the ontological reduction has been accomplished a
posteriori, the coreference of the mental and physical concept
under discussion has been established as well, but
what has not been established is the synonymy. The point
is the following: a mental concept can only be conceptually
reduced to a physical concept if the physical concept is
synonymous with the mental concept. To be synonymous
means to have the same meaning, and not just to have the
same referent (Frege 1892 has famously and convincingly
argued for the distinction between Sinn, i.e., meaning, and
Bedeutung, i.e., reference). For instance, although water is
identical to H2O on the ontological level, the concepts "water"
and "H2O" do not have the same meaning, but merely
the same referent, i.e., H2O. Due to the lack of synonymy
the concept "water" cannot be reduced to the concept
"H2O". A posteriori physicalists carry over this analysis to
the case of "pain = C-fiber stimulation". Although pain is
nothing over and above a C-fiber stimulation on the ontological
level, the mental concept "pain" is not reducible to
the concept "C-fiber stimulation". The pressing question is
whether a posteriori physicalism should be the kind of
physicalism of choice. This issue cannot be settled easily,
yet I want to raise two somewhat related problems for the
a posteriori physicalist.
First, to ontologically reduce mental properties to
physical properties by appealing to the Kripkean
necessary a posteriori seems to be a red herring, for no
account has been given of how mental concepts being
independent and distinct from physical concepts fit into the
physicalist picture. It seems that the problem has carried
over from the ontological level to the conceptual level
without losing any of its original force. Instead of asking
"How do mental properties fit into the physicalist story?"
one must ask "How do mental concepts fit into the
physicalist story?". For instance, Loar claims that mental
concepts, e.g., "pain", are nothing over and above type
demonstratives with the form "that kind of experience".
Therefore, mental concepts are no concepts sui generis,
but they are some kind of demonstratives which in turn are
not any threat for physicalism. The situation is this: on the
one hand, mental concepts are irreducible and therefore
independent from physical concepts, but on the other
hand, mental concepts are demonstratives which are not
in conflict with physicalism and thereby can be viewed as
some sort of physical concepts. The problem for the a
posteriori physicalist is that he cannot have both. Either
mental concepts are physical concepts or they are not.
The a posteriori physicalist seems to beat around the bush
when trying to answer that question. It is at least a little
odd and confusing, if not plainly contradictory, to say that
mental concepts are independent from, but at the same
time some kind of, physical concepts. Second, one of the
aims of every physicalist is parsimony as well as elegance
and simplicity in the construction of his theories.
Consequently, if these tenets of physicalism are taken
seriously, they should also be applied to the conceptual
level and the best way of doing so is by means of a
conceptual reduction. The reason for this is that spelling
out theories gets simpler, more elegant, and more
parsimonious with just one kind of concepts, i.e., just
physical concepts. Let us make the point clear: scientific
psychological theories are not the same as poems. Poems
need a lot of fancy words, but scientific theories just do
not.