Karl Friston

University College London. Chief Scientist, VERSES AI · Functionalist

Karl Friston’s free energy principle is a claim about what it takes for anything to persist. A system that maintains its boundary against a changing environment must, in effect, minimise the difference between the states it predicts and the states it finds itself in. Everything else follows as a consequence. Perception updates the model, action changes the world to match it, and both turn out to be the same operation viewed from different ends.

Active inference turns that into a working framework. An agent selects the action expected to minimise future surprise, which makes exploration and goal seeking fall out of a single quantity rather than requiring separate machinery. It is the most mathematically developed account in the field and the most widely implemented outside it.

What it does not directly supply is consciousness. The principle applies to a thermostat and a bacterium as much as to a brain, so something further is needed to say which self modelling systems have experience. Candidate answers point at the depth of temporal modelling, or at the system modelling itself as the cause of its own predictions. Friston has been careful about that gap, which is more than can be said for some who cite him.

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Known for. The free energy principle and active inference

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