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Emergent Indeterminism

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Emergent Indeterminism

The thesis, developed by Christian List and Marcus Pivato, that genuine indeterminism can exist at a higher level of description — such as the level of agents and their choices — even when the underlying microphysical level is fully deterministic. The indeterminism is not merely epistemic (a matter of ignorance or unpredictability) but ontic: the higher-level description is one at which two or more distinct future trajectories are genuinely open under the laws governing that level.

The mechanism

The argument turns on the level-relativity of determinism itself. Whether a system is deterministic or indeterministic is not a property it has simpliciter — it is a property it has relative to a level of description. A precise microphysical description of a coin toss may admit only one physically possible future; but a macro-level description of the same system — in terms of coarse-grained states of the relevant observable — may admit two or more distinct continuations that are each compatible with the macro-level laws. When this is the case, the system is deterministic at the micro level and indeterministic at the macro level simultaneously, without contradiction.

List and Pivato formalise this in terms of coarse-graining: moving from fine-grained micro-states to coarse-grained macro-states introduces the possibility that multiple micro-trajectories (each uniquely determined) map onto distinct macro-trajectories, leaving the macro-level future open. A toy illustration: imagine a hypothetical system with infinitely many levels of description, alternating between deterministic (odd-numbered levels) and indeterministic (even-numbered ones). The system is coherent; it just cannot be labelled deterministic or indeterministic without specifying the level.

Why this is not just epistemic unpredictability

The standard objection is that what looks like high-level indeterminism is just our inability to track the microphysical state — unpredictability born of computational or informational limitations. List’s reply: we do not treat only microphysical descriptions as real. Thermodynamic properties, chemical properties like acidity, biological and psychological properties — all are recognised as scientifically real even though they are described at a macro level. If our best scientific models of certain macro phenomena treat them as stochastically evolving (as in statistical mechanics, population genetics, or decision theory), we should take that description at face value as a genuinely correct description of those phenomena. To insist the indeterminism is ‘merely epistemic’ is to privilege the micro level in a way that would make solidity, temperature, organisms, and social institutions equally unreal.

Significance for free will

Emergent indeterminism is the mechanism that makes List’s defence of compatibilism distinctive. The classical compatibilist faces a hard question: if the world is physically deterministic, what sense can be made of the claim that an agent ‘could have done otherwise’? Standard responses either abandon the alternative-possibilities requirement or redefine it in counterfactual terms (what would have happened if the agent’s desires had been slightly different) — both feel like retreats from the intuitive force of free will.

Emergent indeterminism offers a third route: genuine alternative possibilities exist at the agential level even if none exist at the microphysical level. The relevant question is not whether the physics is deterministic but whether the agential level is — and the answer can be yes to the first and no to the second without incoherence. This allows free will to require real alternative possibilities without requiring quantum indeterminacy or any departure from a physicalist picture of the world.

Where mainstream views differ

Epistemic objectors argue that macro-level indeterminism is always reducible to ignorance: if we knew the microstate perfectly, we would know the outcome. List’s response is that this proves too much — it would eliminate temperature, acidity, and probability from science as merely epistemic. The objector has to show why macro descriptions are acceptable as real in other domains but not here.

Hard determinists accept the level-relativity of determinism but argue it does not help: the ‘choices’ described at the agential level are still fully fixed by microphysics; calling them indeterministic at a higher level is just a redescription of the same underlying facts. List’s response: this objection assumes only the micro level is genuinely real — precisely the position that emergent indeterminism challenges.

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