Reduction and Elimination in Philosophy and the Sciences

Objects of Perception, Objects of Science, and Identity Statements
Pavla Toráčová, Prague, Czech Republic
I would like to present a brief investigation into the nature
of theoretical identifications, in which we identify an object
of our pretheoretical understanding with an object of
scientific discovery. Traditional examples of such
theoretical identifications are the following: „light is a
stream of photons”, “water is H2O”, “lightning is an
electrical discharge”, “gold is the element with the atomic
number 79”, etc.
Kripke: identity statements
I will start with the account of the nature of identity statements
as provided by Saul Kripke (Kripke 1980). According
to this account, identity statements like “light is a
stream of photons”, “heat is molecular motion”, etc., are
statements that involve two rigid designators that designate
the identical natural phenomenon. A rigid designator
is a term that designates the same object in every possible
world. The key point is that the reference of the rigid designator
is not determined by the description expressed by
or associated with the term as it was suggested by the
traditional theory of reference. According to that traditional
theory, the referent is any object that fulfils the description
expressed, possibly in a disguised form, by the term.
Kripke shows that we often use terms (especially proper
names, but also terms of natural species and natural phenomena)
in a different way: we use them to refer to the
particular object or phenomenon in its necessary existence,
which doesn’t involve the contingent properties the
objects actually bears. Thus, the name “Kurt Gödel” designates
a man who, providing his life had gone differently,
might not have achieved all the things that he achieved.
The name “evening star” designates the object—i.e., the
planet—that, in a different possible world, is not seen in
the evening sky. And similarly, term “heat” designates the
natural phenomenon that, in another possible world,
doesn’t cause the characteristic sensations in sensitive
creatures, and the term “gold” designates a natural species
that might not have been yellow. The properties expressed
by the term (or associated with it)—in the above
examples they might be: “to have proven the incompleteness
of arithmetic,” “to be seen as the first bright object in
the evening sky,” “to produce the specific sensations in
people”—are only contingently true of the objects and
phenomena designated by the terms.
Now it is exactly this feature that makes the
theoretical identifications possible. The structure of the
identifications then may be explained as follows: Initially
we identify the natural phenomenon by phenomenal
qualities that are true of it in our world, and are true of it
only contingently; heat, for example, we identify by the
characteristic sensations it causes in us; gold by the color,
brightness and solidity; water by the characteristic look,
taste and feel, etc. Later in the scientific inquiry, we
discover the essential properties of the phenomenon, i.e.,
the properties that are necessarily true of the
phenomenon. In the statement of identity we then state the
identity of the very object that is referred to by both
terms—initially we refer to it without knowing its essential
properties that we later scientifically discover.
Kripke says:
„What characteristically goes on in these cases of,
let’s say, ‘heat is molecular motion’? There is a certain
referent which we have fixed, for the real world
and for all possible worlds, by a contingent property
of it, namely the property that it’s able to produce
such and such sensations in us. Let’s say it’s a contingent
property of heat that it produces such and
such sensations in people. It’s after all contingent
that there should ever have been people on this
planet at all. So one doesn’t know a priori what
physical phenomenon, described in other terms—in
basic terms of physical theory—is the phenomenon
which produces these sensations. We don’t know
this, and we’ve discovered eventually that this phenomenon
is in fact molecular motion. When we have
discovered this, we’ve discovered an identification
which gives us an essential property of this phenomenon.
We have discovered a phenomenon
which in all possible worlds will be molecular motion—which
could not have failed to be molecular
motion, because that’s what the phenomenon is. On
the other hand, the property by which we identify it
originally, that of producing such and such sensation
in us, is not a necessary property but a contingent
one.” (Kripke 1980, 132-133)
When we say “heat” we actually mean the phenomenon
that is the same in every possible world, the phenomenon
that possesses the essential property “to be molecular
motion”. When we use the term “heat” we mean this phenomenon
from the very beginning although we have no
knowledge of the essential property and the only way we
are initially able to identify it is by the contingent property
“to produce such and such sensations in us.”
Kripke says:
“In general, science attempts, by investigating basic
structural traits, to find the nature, and thus the essence
(in the philosophical sense) of the kind. /.../
Note that on the present view, scientific discoveries
of species essence do not constitute a ‘change of
meaning’; the possibility of such discoveries was
part of the original enterprise.” (Kripke 1980, 138)
The ability of terms to refer to an object not by virtue of the
object’s properties which are known to us (and that are
often expressed by the term)—indeed, to refer to the object,
as it were, despite of these properties—is the crucial
point of Kripke’s theory of reference of proper names. It
also contributes to our understanding of the theoretical
identifications that have been discussed in this paper and
that enjoy considerable interest among philosophers.
However, there are some questions that arise: If the rigid
designator designates the phenomenon independently of
the description that goes with the term, be it the description
of the contingent properties or the description of the
essential properties, how can we know the scientifically
discovered property is the essential one? Indeed, how
could science have ever begun its enterprise, if the once
available properties are regarded as not relevant for the
necessary existence of the phenomenon that science aims
to discover? To be sure, at the beginning of the scientific
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