Podcast brief

Occasionalism: Why Only God Truly Causes Anything

Stephen Nadler talks with Peter Adamson about occasionalism, the 17th century view that God alone is a true cause, and its roots in Cartesian metaphysics rather than the mind-body problem.

A Stoa brief of an episode from History of Philosophy Without Any Gaps

HoP 490 Steven Nadler on Occasionalism

With Stephen Nadler Published April 5, 2026 32 min

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The episode belongs to its makers. This page summarizes its arguments in Stoa's words and points to the moments where they are made. Brief updated September 27, 2026.

The brief

Occasionalism is the claim that no created thing, body or mind, has genuine causal power. Only God truly causes anything. When one billiard ball strikes another, or when you will your arm to move, these events are merely occasions on which God acts, not causes in their own right. Stephen Nadler lays out this 17th century position and traces where it comes from, and where it does not.

A popular story, going back to Leibniz, says occasionalism was invented to solve the mind-body problem: how can an immaterial mind move a material body. Nadler rejects this. He argues that most occasionalists barely mention the heterogeneity of mind and body as a puzzle. The real sources are Cartesian physics and a theory of causal necessity that anticipates Hume. If body is nothing but extension, it has only passive properties like size, shape, and mobility. It cannot contain the active power that Aristotelian substantial forms once supplied. Add an empirical worry, that we never actually observe a necessary connection between colliding bodies, only one event following another, and body-body causation starts to look impossible. Malebranche sharpens this into an argument: a true cause requires a necessary connection to its effect, and only an omnipotent will guarantees that its effect follows. Nadler also distinguishes early Cartesians like La Forge and Cordemoy, who reach occasionalism as philosophers short of a better explanation, from Malebranche, a Cartesian theologian who builds occasionalism into a full system covering grace and freedom.

The conversation's sharpest tension is between Malebranche and Arnauld. Where does human freedom go if God does all the causing. Malebranche answers that the will is a divine striving through the mind, and freedom lies in the capacity to suspend consent to it, a move Adamson compares to Stoic assent. The two thinkers also clash over grace and over whether ideas are mental states or exist in God's own understanding, setting up unresolved questions the conversation leaves for its sequel.

One place to sit with this: ask what changes if you stop thinking of yourself as the cause of your own success, and start asking what you are actually free to withhold.

Strongest arguments

Defining occasionalism and its varieties

0:47

Nadler defines occasionalism as the view that natural objects and minds have no true causal efficacy, only God does. He distinguishes thoroughgoing occasionalism, which denies causal power to bodies, to minds acting on bodies, and to minds generating their own mental states, from partial versions that leave some causal power to minds or bodies.

Medieval Arabic precedents and unclear transmission

2:48

Nadler traces occasionalism's origins to medieval Arabic theologians, the Mutakallimun, especially the Asharites and al-Ghazali, who held that God alone is a true causal agent. He notes that Maimonides described this view in a work available in Latin translation to early modern thinkers, but no direct causal link to Malebranche has been established.

Rejecting the mind-body problem as the origin of occasionalism

5:40

Nadler argues it is a persistent myth, originating with Leibniz's presentation of pre-established harmony, that occasionalism was devised to solve the problem of how immaterial minds and material bodies interact. He says most 17th century occasionalists barely acknowledge this heterogeneity problem, and that the real motivations lie in Cartesian physics, the nature of causality, and theology.

Cartesian metaphysics rules out body-body causation

8:05

Nadler explains that because Cartesian bodies are pure extension with only passive properties like mobility, size, and shape, they cannot in principle possess active causal power, unlike Aristotelian bodies which had substantial forms as active powers. He adds an empirical argument, anticipating Hume, that observation of colliding bodies never reveals a necessary connection, only a sequence of events.

La Forge and Cordemoy versus Malebranche

11:08

Nadler contrasts La Forge and Cordemoy, early Cartesians who reached occasionalist conclusions as philosophers lacking a better explanation for causal relations, with Malebranche, whom he calls a Cartesian theologian whose occasionalism is embedded in a broader theological project including a theory of grace absent in the earlier thinkers.

Malebranche's no-necessary-connection argument for divine causation

16:56

Nadler presents Malebranche's argument that a true cause requires a necessary connection to its effect, and that no finite being can guarantee such necessity because a finite volition can always be thwarted. Only an omnipotent being's will necessarily produces its effect, so only God can be a true cause.

Preserving freedom through consent and suspension of consent

20:32

Nadler explains Malebranche's mature solution to reconciling occasionalism with human freedom: the will is a divine striving through the mind that lands on objects, and human freedom consists in the capacity to suspend consent to that striving rather than to redirect it. Virtue lies in continuing to suspend consent until the will settles on God as the only truly satisfying good.

Disagreements

Malebranche versus Arnauld on grace

25:24

Nadler presents Arnauld's Jansenist view that God directly and intentionally wills each individual conferral of grace, making it necessarily efficacious, against Malebranche's occasionalist view that God distributes grace according to general laws occasioned by the desires of Christ's soul, which can fall on people who fail to use it properly.

Malebranche versus Arnauld on the nature of ideas

29:35

Nadler presents Arnauld's view that ideas, including intellectual concepts, are simply mental states or modes of the human mind, against Malebranche's vision in God doctrine, which holds that intellectual ideas exist in the divine understanding and are only accessed by human minds through God, unlike sensations and pleasures which are true mental states.

Malebranche versus Arnauld on pleasure

24:08

Nadler notes that Malebranche and Arnauld disagree over whether pleasure can render a person truly happy, with Arnauld holding a more austere view and Malebranche holding that pleasure detached from any particular object can contribute to genuine happiness.

Concepts discussed

occasionalism The theory that created things are not genuine causes but only occasions on which God directly produces effects.
causation The relation by which one thing brings about or produces another.
free will The capacity of an agent to choose or will among alternatives in a way that grounds moral responsibility.
Assent The faculty by which we accept or reject impressions, which we must train through an art or set of rules.

Philosophers and works discussed

Malebranche
Arnauld
Descartes
La Forge

Questions this episode answers

What is occasionalism in 17th century philosophy?
0:47

Occasionalism holds that natural objects and human minds have no true causal power. God alone is the true cause of all events, while bodily contact or mental volition merely serves as the occasion for God to act.
Did medieval Islamic philosophy anticipate occasionalism?
2:48

Nadler traces occasionalism to the medieval Arabic Mutakallimun, especially the Asharites and al-Ghazali, who held God as the only true causal agent, though he finds no confirmed direct transmission line to 17th century Cartesians beyond a possible route through Maimonides' Guide of the Perplexed.
Was occasionalism invented to solve the mind-body problem?
5:40

Nadler argues this is a myth originating with Leibniz's framing of pre-established harmony as a rival solution, but most 17th century occasionalists show little concern with the heterogeneity problem, and their real motivations lie in Cartesian physics and theology.
Why did Cartesian philosophy deny that bodies can cause motion in other bodies?
8:05

Because Cartesian bodies consist only of extension, which yields purely passive properties like size, shape, and mobility, they lack any active causal power, unlike Aristotelian bodies with substantial forms. Nadler also notes an empirical argument anticipating Hume that we never observe necessary connection, only sequences of events.
How did Malebranche try to reconcile occasionalism with human free will?
19:35

Malebranche held that the will is a divine striving passing through the mind toward objects, and that human freedom lies in the capacity to suspend consent to that striving rather than to redirect it, with virtue consisting in suspending consent until the will settles on God.
What did Malebranche and Arnauld disagree about regarding grace?
25:24

Arnauld held that God directly and intentionally wills each individual's grace, making it necessarily efficacious, while Malebranche held that God distributes grace occasionally, according to general laws triggered by the desires of Christ's human soul, which can fail to land on properly prepared souls.

Related primary passages

in assent and suspension of assent, that you be not deceived.

Epictetus, Discourses I 4 Read in context

A compact statement of where the work of philosophy actually lies, paired with desire and impulse.

Sources

Epictetus, Discourses I Primary text, Stoa library
History of Philosophy Without Any Gaps, HoP 490 Steven Nadler on Occasionalism Podcast episode, original episode