10.6: Emergence and free will

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Many complex systems have properties, as a whole, that their components do not:

The Rule 30 cellular automaton is deterministic, and the rules that govern its evolution are completely known. Nevertheless, it generates a sequence that is statistically indistinguishable from random.
The agents in Schelling’s model are not racist, but the outcome of their interactions is a high degree of segregation.
Agents in Sugarscape form waves that move diagonally even though the agents cannot.
Traffic jams move backward even though the cars in them are moving forward.
Flocks and herds behave as if they are centrally organized even though the animals in them are making individual decisions based on local information.

These examples suggest an approach to several old and challenging questions, including the problems of consciousness and free will.

Free will is the ability to make choices, but if our bodies and brains are governed by deterministic physical laws, our choices are completely determined.

Philosophers and scientists have proposed many possible resolutions to this apparent conflict; for example:

William James proposed a two-stage model in which possible actions are generated by a random process and then selected by a deterministic process. In that case our actions are fundamentally unpredictable because the process that generates them includes a random element.
David Hume suggested that our perception of making choices is an illusion; in that case, our actions are deterministic because the system that produces them is deterministic.

These arguments reconcile the conflict in opposite ways, but they agree that there is a conflict: the system cannot have free will if the parts are deterministic.

The complex systems in this book suggest the alternative that free will, at the level of options and decisions, is compatible with determinism at the level of neurons (or some lower level). In the same way that a traffic jam moves backward while the cars move forward, a person can have free will even though neurons don’t.