A Gentle Introduction to the Free Energy Principle

What does it mean to be alive? The Free Energy Principle (FEP) is one of the more elegant theories to attempt an answer to this question. Developed by Karl Friston and others from the mid-2000s onward, the FEP builds on and integrates a number of key ideas from cyberneticspredictive coding, and bayesian inference into a single unified theory. At a basic level, FEP is a theory about what enables living organisms to stay alive. It is simple enough to account for single-celled bacteria and powerful enough to account for humans in all our complexity. In this article, I provide an overview of the theory (and its extension as Active Inference) from a completely non-technical perspective. If you are interested in a more mathematically rigorous treatment of the FEP, here are some useful resources (if you want a critique of the theory, there are those too).

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