A Novel Approach to Emergence in Chemistry - Philosophy of Chemistry - page 41

any mechanistic assumptions. He concluded that the possibility of mechanistic
explanation is not essential to the progress of chemistry.
If then chemistry can be a scientific subject and can make steady progress without using the
assumption that a mechanistic explanation of chemical phenomena is possible, it would
presumably have made precisely the same progress if in fact no such explanation had been
possible. (Broad 1925 , p. 74)
While Broad is correct to point out that progress in chemistry happened long
before modern mechanistic explanations of chemical phenomena became available,
it is also true that the mechanistic insights that became available in the twentieth
century have allowed for a great expansion of our chemical knowledge. They
allowed us to better understand the chemical reactions that we knew about, and to
design new reactions. They allowed us to synthesize new molecules, and even new
elements, and to design and create new drugs and materials. In other words,
chemistry would not have made precisely the same progress if quantum mechanics
had not been discovered, although for a long time its own progress was independent
from the progress of physics. Therefore, the autonomy of chemistry in relation to
physics cannot be based solely on the notion of historical autonomy, which is also
only partially defensible.
A second type of autonomy is methodological autonomy. In general, a chem-
istry lab looks very different from a physics lab and what goes on in a chemistry
lab is different from what goes on in a physics lab. But one may respond to this by
saying that while physics and chemistry differ with regard to their methodologies
in general, the methods of some branches of chemistry are in fact physical in
nature. For example, the bond length and angles of molecules are determined
using various types of spectroscopy. Spectroscopy is used in physical and analyt-
ical chemistry to identify the composition of substances or to assess the concen-
tration of a given chemical species; computational methods that make use of
quantum mechanics are used to determine the structure of compounds. Although
in general the methods of chemistry and physics are quite different, this does not
demonstrate that chemistry is autonomous from physics. This is because the
entities and properties that form the subject matter of chemistry could still be
physical entities or properties, even if they are studied with non-physical (i.e.,
chemical) methods. Thus, what philosophers have in mind when they talk about
the autonomy of chemistry in relation to physics is not captured solely by
historical or methodological autonomy.
A stronger notion of autonomy can be discussed - the so-called ontological
autonomy of chemistry. Indeed, this stronger notion of autonomy is the one which
presents the most philosophical interest. But what does it amount to? I make the
following proposal: a discipline is ontologically autonomous from another if the
ontology of the first is distinct from the ontology of the second. To be informative,
this proposal must specify what it is meant by “ontology”. Luckily, we have a
pretty decent understanding of what an ontology is. Arguably, an ontology must