A Novel Approach to Emergence in Chemistry - Philosophy of Chemistry - page 47

of chemistry. The question that I think needs to be taken seriously is this: if the
entities that chemistry talks about are composed of nothing but the entities that
quantum mechanics talks about, why do we have chemistry and not just applied
quantum mechanics? Are there any good reasons for upholding the ontological
autonomy of chemistry, as opposed to just a merely epistemic, methodological or
historical autonomy? If the kind of stuff chemistry talks about consists of the kind of
stuff that quantum mechanics talks about, what justifies belief in chemical properties,
or that in chemical laws or explanations? Are there even chemical properties, laws,
and explanations, as opposed to just complex quantum-mechanical properties, laws,
and explanations? Does chemistry latch onto genuine features of the world, which
inhabit a distinct ontological level? Or rather the chemical properties and laws are
just useful instruments for predicting and explaining, but ultimately with no claim to
the fundamental truths about nature, which remain microphysical? If chemistry
is emergent, then these questions may find satisfactory answers. If one can show
that there really are chemical entities, properties, laws and explanations, then the
ontological autonomy of chemistry can be secured.
So far, the philosophical efforts towards a theory of ontological emergence in
chemistry focused on the emergence of entities. For Broad, what was emergent was
chemical compounds; for Hendry, what is emergent is molecules (molecular struc-
ture). But an ontology contains more than just entities; it also contains processes,
properties, phenomena, laws, and on some understandings of ontology, even expla-
nations. All these are just as legitimate elements of an ontology as entities. The
approach I am proposing focuses not on entities, but on properties and laws, which
can be used in sui generis chemical explanations. It starts from the observation that
many chemical properties are defined not in terms of their constitutive microphys-
ical structure, but functionally, in terms of their efficient roles. In particular, many
chemical properties are defined by their behaviour in relation to other chemical
properties, in the context of chemical reactions. The idea that a thing is defined by
what it does and not by what it consists of was first advocated by Alan Turing, in the
foundations of computer science and artificial intelligence (Turing 1950 ). Turing
thought about it via an analogy with the mathematical concept of a function ( 1950 ,
p. 439). Turing ' s idea was quickly adopted in the philosophy of mind, where it
served as a basis for an alternative theory of mind, different from both the identity
theory and behaviourism (Putnam 1975a , b ; Fodor 1974 ). The theses of function-
alism and multiple realizability have also inspired anti-reductionist arguments in
the philosophy of biology (Kitcher 1984 , 1999 ; Kincaid 1990 ). But chemistry is,
I believe, the ideal domain where this sort of anti-reductionist argument can be
made. The fact that chemical properties can be intersubjectively scrutinized, that
they are amenable to measurement, experiment and to a quantitative understanding
to a greater extent than those in the other special sciences makes chemistry one of
the best case studies (see also Scerri and McIntyre 1997 , p. 227; Humphreys
1997b ). Chemistry is the discipline that is in some sense closest to physics, and
therefore it is the first domain outside physics itself where we can observe func-
tional properties and irreducibility/emergence, if these truly exist.
The approach to emergence I

m proposing starts from the observation that many
chemical properties are defined not in terms of their constitutive microphysical
structure, but functionally, in terms of their efficient roles. So far, philosophers of

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