Phase Transitions: A challenge for reductionism?

Presenter: Patricia Palacios (Munich Center for Mathematical Philosophy)

Phase transitions are sudden changes in the phenomenological properties of a system. Some common examples include the transition from liquid to gas, from a normal conductor to a superconductor, or from a paramagnet to a ferromagnet. Nowadays phase transitions are considered as one of the most interesting and controversial cases in discussions around reduction and emergence in science. This is because they make particularly salient the constitutive role played by idealizations in the inference of macroscopic behavior from a theory that describe microscopic interactions. In fact, it appears that statistical mechanics (a well-established microscopic theory) cannot account for the behavior of phase transitions as described by thermodynamics (a macroscopic theory) without the help of infinite idealizations.

In this contribution, I analyze the use of infinite idealizations in the theory of classical phase transitions and evaluate the extent to which they impose a challenge for the reduction of the phenomena. My main contention is that classical phase transitions are, in fact, compatible with inter-theory reduction.