Is the Brain an Organ for Prediction Error Minimization?

An influential body of research in neuroscience and the philosophy of mind asserts that the brain is an organ for prediction error minimization. I clarify how this hypothesis should be understood, and I consider a prominent attempt to justify it, according to which prediction error minimization in the brain is a manifestation of a more fundamental imperative in all self-organizing systems to minimize (variational) free energy. I argue that this justification fails. The sense in which all self-organizing systems can be said to minimize free energy according to the free energy principle is fundamentally different from the alleged sense in which brains minimize prediction error. Thus, even if the free energy principle is true, it provides no support for a theory of the brain as an organ for prediction error minimization – or any other substantive theory of brain function