The brain is an organ with a function, namely to enable the organism to maintain itself in its expected states. According to the free energy principle, this is to say that it minimizes prediction error on average and over the long run. This is a controversial idea, with extreme explanatory ambition. It might be considered not only controversial but also preposterous. But the philosophy of science-based discussions above have sought to show that it is not in fact preposterous. The different ways in which it might be preposterous either do not apply, misunderstand the principle, or would also apply to the paradigmatically non-preposterous theory of evolution. The free energy principle yields a theory that should, indeed, strongly explain away competing theories. The free energy principle is an account that displays a number of explanatory virtues such as unification and fecundity. It is therefore not reasonable to detract from the principle by claiming it is preposterous or too ambitious. Scientifically speaking, what remains is to assess the evidence for and against the free energy principle and consider how, more specifically, it explains our mental lives (a task I undertake in Hohwy 2013). Speaking in terms of philosophy of mind, there remain questions about what type of functionalist theory the free energy principle is, how it performs vis-à-vis traditional questions about functionalism and the realizers of functional roles, and, finally, some more metaphysical questions about what it says about the nature of the mind in nature. None of these philosophical issues are apparently more damning for the free energy principle than they are for other, previously proposed accounts of the nature of the mind, and there is reason to think that with the free energy principle a new suite of answers may become available.