JH8 Determinism Dp

DeterminismClassical Compatibilism

Determinism and Compatibilism

Stephan Leuenberger

University of Glasgow

JH8 Metaphysics

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New topic: free will

Material Objects

Time

Causation

Free Will

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[The free will issue is] the most contentious question ofmetaphysics, the most contentious science.

David Hume, An Enquiry Concerning Human Understanding.

Someone’s having free will is often taken to be a necessarycondition for their being morally responsible for their actions.

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Compatibilism and Incompatibilism

A great divide in the free will debate:

Compatibilism Free will is compatible with determinism.

Incompatibilism Free will is not compatible with determinism.

What is determinism, then?

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Determinism: conceptual and empirical questions

Whether determinism is true is an empirical question.

What it takes for determinism is true is (arguably) aphilosophical question.

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An intelligence knowing all the forces acting in nature at agiven instant, as well as the momentary positions of allthings in the universe, would be able to comprehend inone single formula the motions of the largest bodies aswell as the lightest atoms in the world, provided that itsintellect were sufficiently powerful to subject all data toanalysis; to it nothing would be uncertain, the future aswell as the past would be present to its eyes.

Pierre Simon de Laplace, Théorie analytique des probabilités, Paris, 1820, Preface. Translation quoted afterErnest Nagel, The Structure of Science, Hackett Publishing, 1961, pp. 281-282.

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Determinism and prediction

D1 Determinism is true if and only if every event can bepredicted.

The left-right half of D1 is:If determinism is true, every event can be predicted.Problem: principled limits to measurements.

The right-left-right half of D1 is:If every event can be predicted, then determinism is true.Problem: crystal balls.

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Determinism and causation

D2 Determinism is true if and only if every event has acause.

The right-left half of D2 is:If every event has a cause, then determinism is true.Problem: non-deterministic causation.

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Imagine a materialistic world consisting of massiveparticles whose trajectories are straight lines exceptwhere the trajectories happen to intersect. Everyinteresting event or happening in this world is ahappening to a particle, viz., a change of position, acollision, etc. And every such event has a cause in termsof the earlier events . . .. Yet this world may or may not bedeterministic . . . ; for it is consistent with the description Ihave given that many future complements are compatiblewith the present state of the world.

John Earman, A Primer on Determinism, Springer 1986, p. 6.

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Determinism and causation, continued

D3 Determinism is true if and only if every event has acause, and like causes always have like effects.

This entails:If determinism is true, then every event has a cause.Potential counterexamples: first event; complete history.

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Another suggestion:

Determinism is true if and only if for all times t , thehistory of the states of the universe up until tdetermines the state of the universe at any time aftert .

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Divergence

Definition (Divergence)

Possible worlds w and w′ diverge =df w and w′ are notqualitatively alike, but some initial segments of w and of w′ that areintrinsically alike.

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Defining determinism via divergence

First attempt:

Determinism is true if and only if no two possibleworlds diverge.

Problem: counterinductive worlds.

Second attempt:

Determinism is true if and only if among the possibleworlds of the relevant kind, no two diverge.

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A better attempt

D4 (Montague-Lewis) Determinism is true if and only if among thepossible worlds where all actual laws of nature aretrue, no two diverge.

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What does determinism profess? It professes that thoseparts of the universe already laid down absolutelyappoint and decree what the other parts shall be. Thefuture has no ambiguous possibilities hidden in its womb:the part we call the present is compatible with only onetotality. Any other future complement than the one fixedfrom eternity is impossible. The whole is in each andevery part, and welds it with the rest into an absoluteunity, an iron block, in which there can be noequivocation or shadow of turning.

William James, lecture to the Harvard Divinity School, 1884, quoted after John Earman, A Primer on Determinism,Reidel, Dortrecht, 1986, p. 4/5.)

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Readings on determinism (optional)

John Earman’s Primer on Determinism (Reidel, Dordrecht,1986) discusses proposed definitions of determinism in ch. 2.The rest of the book is an in-depth investigation of the statusof determinism in various physical theories.

David Lewis’ “New Work for a Theory of Universals”,Australasian Journal of Philosophy 61 (1983), pp. 343-377,contains a short but influential discussion of determinism.

Ch. 9 of Peter Smith, Explaining Chaos, Cambridge UniversityPress, 1998, talks a bit about the determinism and its relationto chaos theory.

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Freedom as absence of constraints

A compatibilist analysis of ‘x is free’:

x has the ability to do what she wants; and

there are no constraints preventing x from doing what shewants.

Freedom thus understood is compatible with determinism.

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Freedom to do otherwise

Suppose x wants to do A , and does A .Does x have the freedom to do otherwise?

Yes, according to the compatibilist, iff

x has the ability to avoid doing A ; and

x is not coerced to do A .

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Freedom of action and freedom of will

Freedom of action: freedom to do what one chooses.

Freedom of will: choosing freely.

Objection to classical compatibilism: they give an account of freeaction, but not of free will.

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Choices as actions

Compatibilist analysis of ‘x is free to choose A ’:

x has the ability to choose A ; and

there are no constraints preventing x from choosing A .

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Confusions about determinism

determinism versus coercion

determinism versus control by other agents

determinism versus mechanism

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Confusions about determinism, continued

determinism versus fatalismA fatalist believes . . . not only that whatever is aboutto happen will be the infallible result of causes thatprecede it, but moreover that there is no use instruggling against it; that it will happen however wemay strive to prevent it . . . [Fatalists believe thatman’s] character is formed for him, not by him;therefore his wising it was formed differently is of nouse; he has no power to alter it. This is a granderror. He has, to a certain extent, a power to alter hischaracter. His character is formed by hiscircumstances . . . but his own desire to mold it in aparticular way is one of the circumstances, and byno means the least influential.

John Stuart Mill, A System of Logic, New York (Harper & Row), 1874.

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Suggested readings

Daniel Dennett, Elbow Room.

Robert Kane, A Contemporary Introduction to Free Will, OUP2005, ch. 2.

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Documents

JH8 Determinism Dp