Reduction and Elimination in Philosophy and the Sciences

Reduction Revisited: The Ontological Level, the Conceptual Level,
and the Tenets of Physicalism
Markus Gole, Graz, Austria
1. Reduction and Physicalism in Philosophy
of Mind
When the topic of reductionism is addressed, especially
within philosophy of mind, one cannot help but summon
the topic of physicalism as well. Physicalism, broadly construed,
can be defined as the thesis that there is nothing
over and above the physical: all there is is physical, in one
way or another, and there are no such things as nonphysical
substances, events, properties and the like which
escape the physicalist story. For instance, when I bump
into the table in my kitchen and thus hurt my leg, the only
story there is to tell is simply the story of the natural sciences.
Such a story might go like this: after having
bumped into the table, certain physiological mechanisms
are activated, e.g., the information of tissue damage is
transmitted via nerve fibers from the leg to the brain where
certain neurons are caused to fire, which in turn cause
other neurons to fire, and finally the statement "Ouch, my
leg hurts!" is uttered followed by wincing and groaning. It
should be noted that the statement "Ouch, my leg hurts!" is
solely used as an abbreviated form of the neuron firing talk
and, similarly, wincing and groaning are themselves nothing
over and above another neuron firing story. All we
need to fully and exhaustively characterize a painful experience
is a characterization of the physical events which
are solely couched in physical concepts and there does
not seem to be a need to use any mental concepts like
"pain", "want", "desire", and so on. But why should anyone
be a physicalist? The answer to this question leads us to
the tenets of physicalism which I take to be ontological
parsimony as well as elegance and simplicity in the construction
of our theories. The ontological parsimony stems
from abandoning non-physical entities, for there is no need
to introduce mental entities in order to explain what is going
on when someone is in pain. Or, put differently, all
mental entities have fallen prey to Ockham's razor. By
elegance and simplicity I mean that it gets easier if only
one kind of entities, i.e., physical entities, are used to construct
theories compared to two kinds of entities, i.e.,
physical and mental entities. Thereby, pain theories become
simpler and more elegant once mental entities have
been crossed out.
I turn now to the reduction part. In contemporary
philosophy of mind, it is widely accepted, both by the
physicalist and dualist, that if a mental property can be fully
characterized in the language of physics, then the mental
property in question is actually a physical property. The
translation of mental expressions into physical
expressions, or put in another way, the identity between
the mental concept and the physical concept, can be
thought of as a conceptual reduction and the identity
between the mental property and the physical property can
be thought of as an ontological reduction. Therefore,
reduction represents a relation between two concepts on
the one hand and between two things, in this case
properties, on the other hand. This relation is the relation
of identity, because one concept or property is nothing
over and above another concept or property respectively.
Moreover, the conceptual reduction is sufficient for the
ontological reduction. However, whether the reverse is true
is a matter of debate. The present paper is an attempt to
tackle that question and it is argued that a conceptual
reduction follows from an ontological reduction as well, but
only under the background assumption that a priori
physicalism is true. It is also argued that if the tenets of
physicalism are taken seriously, then a posteriori
physicalism should be dropped in favor of a priori
physicalism.
2. Conceptual Reduction, Ontological Reduction,
and Physicalism
I would like to begin this section by defining a priori and a
posteriori physicalism. Insofar as the physicalism part is
concerned, a priori as well as a posteriori physicalism
agree that all there is is physical. Furthermore, proponents
of both branches of physicalism are committed to the claim
that, necessarily, all the mental phenomena are entailed
by the physical phenomena. Thus, if all the physical things
are fixed, then all the mental things are fixed, too. Insofar
as the a priori/a posteriori part is concerned, the discrepancy
arises. A priori physicalists (e.g., Jackson 1998) hold
that all the mental phenomena are entailed a priori, i.e.,
solely on grounds of the meanings of the words involved.
For instance, the mental concept "pain" refers to the mental
property "being in pain" and the physical concept "Cfiber
stimulation" refers to the physical property "having a
C-fiber stimulation". If a priori physicalism is true, the concepts
"pain" and "C-fiber stimulation" are two words with
the same meaning, in fact, they would be synonymous
expressions and "pain" could be conceptually reduced to
"C-fiber stimulation". Because of their synonymy, both
concepts would have the same property as their referent
and a fortiori, the property of being in pain could be ontologically
reduced to the property of having a C-fiber stimulation.
In contrast, the a posteriori physicalist (e.g., Loar
1997) argues that the mental phenomena are entailed only
a posteriori and it is a matter of scientific investigation to
find out that the properties in question are actually one and
the same property. Because of this a posteriori nature of
the identity claim, the concepts involved are independent,
for it is impossible for the mental phenomena to be
entailed by the physical phenomena solely on grounds of
the meanings of the words. That is, a posteriori
physicalists allow and argue for an ontological reduction
and in the same vein argue against a conceptual
reduction. I think it is safe to say that all a posteriori
physicalists are sympathetic to Kripke's (1980) framework
of necessary a posteriori identity claims and his canonical
example "water = H2O". It was an empirical discovery that
water is one and the same as H2O. Nevertheless,
conceptual analysis did not get us to say that water is
nothing over and above H2O, and the reason is that the
concepts "water" and "H2O" do not mean the same; they
are not synonymous. So, a posteriori physicalists see the
identity claim "pain = C-fiber stimulation" akin to the
identity claim "water = H2O". Therefore, if a posteriori
physicalism is true, pain is ontologically, but not
conceptually, reducible to a C-fiber stimulation.
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