Chemistry Reference
In-Depth Information
Written out
in full
the attribution of an affordance has the form of a
conditional -
if a certain procedure is carried out on a certain substance then it
will display a certain attribute or yield a certain substance
'
. So adding carbon to
iron increases the tensile strength of a rod, that is a property it displays only when
put into tension in some machine. Adding zinc to a solution of hydrochloric acid
yields a gas that after several decades of eighteenth and nineteenth century debate
we now label
'
'
hydrogen
'
. Hydrochloric acid affords hydrogen only in certain
particular circumstances.
8.5.1 Categories of Affordances
The pattern in which the second mereological fallacy can infect the validity of
reasoning in chemistry appears in the inferences we are inclined to make linking the
results or products of analytical processes to the material stuffs from which they
were derived. The methodological question is whether the products of an analytical
procedure were constituents of the being on which the process was exercised.
In the root procedures in chemistry do we have analysis of things into their parts
or the genesis new beings? To assume that analytical processes directed towards
targets
always
yield constituents is to fall into the
product-process
fallacy, or the
'
'
second mereological fallacy. The concept of
can throw light on how
this fallacy comes about and in what circumstances. It is not a fallacy to draw
inferences about the molecular weight of a certain compound from knowledge
of the atomic weights of the products of its analysis.
affordance
'
'
1. Affordances as substances - things and stuffs - for example, distillation affords
alcohol. There was alcohol in the liquor before it was separated out, so to say that
alcohol was a constituent of the liquor is a valid inference. Electrolysis of silver
nitrate solution yields silver ions, so to say that silver atom-cores were parts of
the solution is a valid inference.
2. Affordances as attributes - properties - for example, heating a solid affords
liquidity; passing light through a prism affords a spectrum of colours on a white
surface. Was liquidity a hidden property of the solid? Surely not. But Newton
realised that coloured rays were a hidden and constitutive property of white light.
3. The part/whole distinction for the mass mereology discussed by Needham
(
2005
) also requires the concept of
. The parts of the sea extracted
by buckets have the values of certain properties, such as quantity, determined by
choice of bucket. The sea affords buckets full as well as thimbles full. However,
it seems that there is no temptation to fall into a version of the second
mereological fallacy in these examples. It is not a fallacy to declare that a bucket
of water is a part of the sea.
affordance
'
'
Science progresses by asking whether there is a hidden property of the being
which yields the affordance. When subject to the appropriate manipulations mate-
rial substances afford spectra. But spectral colours are not parts of the substance that
