Chemistry Reference
In-Depth Information
chemistry have not given appropriate consideration to this idea. For example, the
volume which was published as a result of the 3rd Erlenmeyer Colloquy for the
Philosophy of Chemistry, titled “The Autonomy of Chemistry” does not even
mention chemical functional properties, despite the broad consensus and shared
anti-reductionist attitudes among the participants (Janich and Psarros
1998
). In fact,
the idea of multiple realizability (which is often associated with functionalism) has
been regarded with distrust in the philosophy of chemistry, being labelled as
“wishful thinking” (Scerri
2000
). Yet, multiply realizable properties feature prom-
inently in the discussions about the limits of reductionism in philosophy of mind,
philosophy of biology, and philosophy of physics (Batterman
2000
,
2002
). I think
chemistry makes no exception; on the contrary, I think chemistry provides us with
some of the best examples of functional, multiply realized properties.
Consider the property of being an acid. On the Arrhenius definition, acids are
defined as those substances which, when dissolved in water, increase the concen-
tration of hydrogen ions in the solution. On the Brønsted-Lowry definition, an acid
is any compound that can donate one or more protons to other chemical species in
chemical reactions. And on the Lewis definition, acids are those compounds that
accept a pair of electrons from another compound in a chemical reaction. All these
definitions are functional, i.e., they pick out acids not by referring to their micro-
physical structure, but by referring to their behaviour in relation to other chemical
substances. Compare the property of being an acid with the property of being an
alcohol. Alcohols are those molecules that have a hydroxyl group bound to a
saturated carbon atom. This microstructural commonality can be invoked when
explaining the chemical properties of alcohols. In a certain sense of the term
“reduction”, the property of being an alcohol reduces (i.e., is identical) to the
property of being a microphysical system containing a hydroxyl group bound to a
saturated carbon - all alcohols and only alcohols have this microstructural property.
But the property of being an acid (or, more accurately, acidity in general) does not
“reduce” in a similar manner to any given microstructural property. Of course, one
may accept that any given instance of an acid (or acidic behaviour) is identical with
a given instance of a physical property or process - token reductionism may hold.
But acidity as such (as a property type) cannot be identified to any given micro-
structural property - type reductionism fails. Acidity is first and foremost a behav-
iour, which can be realized by many systems of electrons and nuclei. In
philosophical lingo, the property of being an acid is said to be
multiply realized
.
Because of this, it is not discernible at the lower level as a microstructural property.
It “emerges” out of the microphysics, and becomes visible only in the context of a
chemical reaction, as a pattern of chemical behaviour.
Acidity may not be the only functional property in chemistry: arguably, the
property of being a base, a reductant, an oxidant may also be functional. To these,
one may add the property of being a metal. More than 70 % of existing chemical
elements are metals; at standard conditions of temperature and pressure, 91 ele-
ments out of 117 are considered metals. Twelve out of 18 groups in the periodic
table are occupied exclusively by metals - alkali elements, alkaline earth elements,
lanthanides, actinides, and the transition elements, are all metals. Some elements in
group 13 to group 16 are metals too. As one can expect, the microstructural
description for all these atoms will look disunified. Finding a microstructural
