A Novel Approach to Emergence in Chemistry - Philosophy of Chemistry - page 51

can be a virtue. By not going into the details, the explanation is unified : it sees
various compounds as instances of a single kind of substance, namely acid. Since
the explanation is insensitive to the particular compounds responsible for the acidic
properties of the rain, it is robust : it remains valid despite variations in the
composition of the acid rain that may occur from year to year. Also, the explanation
has a broad explanatory range : it can account for the loss of detail in the marble
antefixes on buildings situated in different geographical locations, where the acid
rain has a different chemical composition. Since it features a sui generis chemical
property, the explanation above may be called a sui generis chemical explanation.
In contrast with the explanations mentioning the particular reactions (which per-
haps could be seen by a ruthless reductionist as physical explanations), the expla-
nation invoking the acidity of the rain is robust, unified, and has a broad explanatory
range. But this happens only because it is a higher level explanation, i.e., an
explanation which employs a higher level concept.
If chemical properties, laws and explanations are not identical or coextensive
with physical properties, laws and explanations, then they should be treated as sui
generis . The existence of sui generis chemical properties, laws and explanations
supports the idea that chemistry is ontologically autonomous from physics, which is
one of the two defining characteristics of emergence. The other characteristic of
emergence, namely dependence, is also satisfied by the account I m proposing. The

functional chemical properties like acidity are made possible by the physical
processes involving systems of electrons and nuclei. The kind of emergence I

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m
proposing has no problems embracing supervenience physicalism - the idea that
any physical duplicate of our world is a duplicate of our world simpliciter. I take the
following to be true: (i) if the microphysical level were to disappear, the chemical
level would disappear as well; (ii) any change at the chemical level must involve a
change at the microphysical level; (iii) any microphysical duplicate of our world
will be a chemical duplicate.
Since the view I

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m proposing meets both characteristics of emergence, and is
made possible by the existence of functional properties, I will call it functional
emergence . The use of the term “emergence” is appropriate because the existence
of functional properties in chemistry supports the layered view of the world
characteristic of emergentism. The sui generis chemical properties, laws and
explanations function at a higher level than the physical properties, laws and
explanations; they depend on the physical level, but they do not reduce to it.
I take it that supervenience physicalism is an uncontroversial thesis, which can
be shared by reductionists and emergentists alike. But, as mentioned earlier, not all
versions of emergence share a deeper physicalist commitment, namely the com-
pleteness of physics. For example, those versions of emergence which are commit-
ted to the emergence of entities (e.g., Broad

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s) will conflict with the
thesis that all physical events are determined (or have their chances determined)
entirely by prior physical events according to physical laws. For if there are sui
generis chemical entities which are capable of causing physical events (via down-
ward or horizontal causation) then the causes of those events won

s or Hendry

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t be strictly
speaking physical; they will be chemical . But functional emergence does not take
this step. On the view that I

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m proposing, entities may be wholly resultant.

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