It is sometimes thought that philosophers have little to offer those who think about the science of complex systems. There are, however, two philosophical ideas that seem crucial in considering the very definition of complexity. The first is the distinction between "ontology" and "epistemology", wherein one recognizes the difference between limits provided by reality versus those provided by our knowledge of reality. The second concerns the debate over "non-reductive materialism" in the philosophy of mind, wherein philosophers have discovered a way to defend non-reductive explanations of emergent phenomena, even though they are materially dependent upon causal relations at lower levels. In my paper, I argue that we may defend the science of complex systems as a project involving the explanation of non-reductive phenomena that are epistemically emergent.
