Occasionalism

Malebranche's route to occasionalism runs directly through Descartes's own dualism: having accepted that mind and body are genuinely distinct substances with nothing in common, Malebranche concluded that Descartes's proposed interaction at the pineal gland could not actually work, since two substances with no shared nature have no basis on which to causally affect one another; the only remaining candidate capable of connecting a volition in the mind with a movement in the body, he argued, is God, whose will alone has the power to bridge such a gap, and who does so with perfect, lawlike consistency, giving the appearance of natural causation without there being any causation among creatures at all.

Al-Ghazali arrived at essentially the same structural conclusion from within Islamic theology, in his Incoherence of the Philosophers, arguing against the Aristotelian philosophers of his day, most prominently Avicenna, that treating fire's burning of cotton as a necessary causal connection, rather than as God's habitual but entirely free choice to create burning on the occasion of contact, illegitimately limits divine omnipotence by binding God to act through fixed intermediate causes; for Al-Ghazali, God remains free at every instant to withhold the burning, and its regular occurrence is a matter of divine custom, not natural necessity. Averroes, defending the philosophers against Al-Ghazali in his own rebuttal, argued the occasionalist picture makes the entire natural world, and the scientific reasoning built on studying it, arbitrary and unintelligible, since a world with no real natural causal connections offers no stable object for rational inquiry to investigate in the first place, a criticism occasionalists have generally answered by insisting that God's perfect consistency, though not logical necessity, is more than sufficient ground for reliable natural science.

It is genuinely striking that European Cartesian philosophy and classical Islamic kalam arrived at the same distinctive metaphysical position from almost entirely independent starting points, one working from the technical demands of substance dualism, the other from a theological commitment to unlimited divine omnipotence, and the convergence is exactly the kind of case this atlas exists to register: occasionalism is one claim, held twice, in two traditions with no direct line of influence connecting Malebranche to Al-Ghazali six centuries earlier.

The position stands opposed most directly to interactionism, which affirms real, direct causal power passing between finite things, and its critics on both sides of that divide, Averroes among the philosophers and most interactionist theologians among the theistic traditions, press the same underlying worry: a universe with no real secondary causation seems to make ordinary explanation, and ordinary moral responsibility for actions genuinely one's own, difficult to sustain. Occasionalism's defenders, in both traditions, answer that God's absolute sovereignty over causation is worth this cost, and that regularity sustained by God's consistent will is no less reliable, and arguably more secure, than regularity supposedly built into matter itself.