This paper concerns reductionist views about psychology and the special sciences more generally. I identify a metaphysical assumption in reductionist views which I dub the ‘Micro–Macro Mirroring Thesis’. The Mirroring Thesis says that the relation between the entities of any legitimate higher-level science and their lower-level realizers is similar to that between the entities of thermodynamics and statistical mechanics. I argue that reductionism implies the Thesis, and that the Thesis is not a priori. It is more difficult to tell whether the Thesis is true, and I indicate some relevant considerations.