Chemistry Reference
In-Depth Information
8.6 Chemical Affordances
It is only too easy to carry the concept of an affordance further from dispositions
and capacities to constituents. But as Earley (
2005
) argues the sea does not contain
salt as a constituent- though it does contain sodium and chloride ions. As a result of
subjecting sea water to a certain procedure, for example evaporation, it will afford
that white crystalline substance we call
of which there is
none in the sea
.
In light of the above discussion of mereology, Earley
salt
'
'
s insight can be expressed as
pointing out an example of the second mereological fallacy. A frozen lake has the
same molecular structure in case it affords walking to a wolf but does not afford
walking to the moose it is stalking. The same structure explains its strength relative
to the weight of a wolf and its weakness relative to the weight of a moose. Though
an affordance is grounded in some feature of the substance from which it is elicited
it is relative to the local situation. However, such a feature may have been proposed
on the basis of shaky reasoning - in short from a move which involves the
commission of the second mereological fallacy - going from products (affordances)
to constituents, the grounding of affordances.
We do not have clear and determinate criteria for either the qualitative or the
numerical identity of electrons. In so far as these
'
are affordances on the
lower edge of the chemical domain to build a realist theory of atomic structure on
the basis of projecting them back as constituents of the atoms which afforded them
is a mereological fallacy of the second type. J-P. Llored and I have written
extensively about this fallacy in the context of Mulliken
items
'
'
s introduction of molecular
orbitals vice molecular orbits (Llored and Harr´
2011
). Orbits would be the
tracks
particulate electrons follow around molecules as binding the atomic constituents
into a whole, but the conclusion from the existence of a certain kind of track to the
existence of an electron or any other appropriate charged
particle
as an entity in all
circumstances is fallacious (Harr´
1990
). So we come at this from two different
directions. Tracks as observed in colliders are used to infer the existence of particles
with certain properties, while the Mulliken move is to resist the reading back of
electron affordances into orbiting bits of electrically charged stuff. Only by bring-
ing in the concept of affordance and the second mereological fallacy are we able to
sustain his intuition with a metaphysical argument.
However, there are clear and determinate criteria for the qualitative and nume-
rical identity of atom-cores (ions) as affordances of certain procedures exercised on
molecules, such as electrolysis, backed up by direct observation as described above
in the use of travelling tunneling microscopes as developed by Gerd Binnig and
Heinrich Rohrer (
1986
). To declare that molecules are structures of which the
constituents are atomic cores is not a philosophical error.
To sum up the argument: we find a ubiquitous role played by electrons in
chemical theory. Electrons-as-particles phenomena can be obtained from atoms
by means of certain procedures such as the cloud chamber. Electrons as wave
phenomena can be obtained from atoms by distinctive and independent procedures
such as double slit experiments. But it does not follow that the electrons obtained
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