Two Varieties of Occasionalism

As Elisabeth of Bohemia famously pointed out, Descartes appears to be committed to the following inconsistent triad:

1. In every instance of causation, there is an a priori conceptual connection between cause and effect.
2. There are no conceptual connections between mind and body.
3. Mind and body interact causally.

The most common response to this problem among Descartes’s 17th century followers was occasionalism, the view that bodily phenomena do not genuinely cause mental phenomena but are merely reliably correlated with them, and vice versa, so that bodily phenomena may be called occasions of mental phenomena and mental phenomena may be called occasions of bodily phenomena.

The best-known advocate of this strategy (and, indeed, the best-known Cartesian after Descartes) was Nicolas Malebranche. Malebranche famously adopted full-strength occasionalism that had been popular among Medieval Islamic philosophers and theologians. On this view, there are no ‘secondary causes’ at all. God is the only true cause and created things can only serve as occasions for God to exercise God’s power. Malebranche has many arguments for this view, but one of them derives directly from the Cartesian doctrine of the a priori intelligibility of causation:

We have only two sorts of ideas, ideas of minds and ideas of bodies … since the idea we have of all bodies makes us aware that they cannot move themselves, it must be concluded that it is minds which move them. But when we examine our idea of all finite minds, we do not see any necessary connection between their will and the motion of any body whatsoever … But when one thinks about the idea of God, i.e., of an infinitely perfect and consequently all-powerful being, one knows that there is such a connection between His will and the motion of all bodies, that it is impossible to conceive that he wills a body to be moved and that this body not be moved. We must therefore say that only His will can move bodies (The Search After Truth, tr. Lennon and Olscamp, 448)

Malebranche’s view here is a much more substantive revision of Descartes than is required to escape the inconsistency above. There is a general tendency in Cartesian thought to contrast body as passive with mind as active, but Malebranche’s view appears to make created mind every bit as passive as body.

An alternative view would maintain divine occasionalism with respect to mind-body interaction, but attribute genuine activity to the mind in internal actions like imagining and willing. Indeed, Malebranche himself sometimes seems tempted by such a view, although his arguments for occasionalism appear to rule it out.

An even smaller tweak to respond to the problem of the causation of mental states by bodily states is possible, and is suggested by remarks Descartes makes in “Comments on a Certain Broadsheet”:

there is nothing in our ideas which is not innate to the mind or the faculty of thinking, with the sole exception of those circumstances which relate to experience, such as the fact that we judge that this or that idea which we now have immediately before our mind refers to a certain thing situated outside us. We make such a judgement not because these things transmit the ideas to our mind through the sense organs, but because they transmit something which, at exactly that moment, gives the mind occasion to form these ideas by means of the faculty innate to it (CSM 1:304, emphasis added).

This passage suggests, not divine occasionalism, but a sort of finite occasionalism, whereby the states of material systems give occasion for the (genuinely causal) activity of the finite mind in forming ideas of the things around it.

This hint is picked up by Arnauld and Nicole in the Port-Royal Logic:

It is thus false that all our ideas originate in the senses. On the contrary, one can say that no idea in the mind originates in the senses, although motions in the brain, which is all the senses can bring about, may provide the occasion for the soul to form various ideas that might not have been formed without this occasion (Logic, tr. Buroker, 30, emphasis added)

Here note again that it is the finite mind itself that forms the ideas and not God.

This line of response to the inconsistency with which we began makes good sense with basic Cartesian commitments, commitments which Arnauld emphasizes (against Malebranche) in On True and False Ideas. Cartesian metaphysics begins from two (alleged) clear and distinct ideas: the idea of body as extended substance and the idea of mind as thinking substance. Extension is the principal attribute of body and thought is the principal attribute of mind. Every property of a substance must be an intelligible modification of its principal attribute. A modification of an attribute is a way of possessing that attribute, i.e., a way of being extended or a way of thinking. Thus every property of a mind must be a way of thinking. But thinking is an activity, while being extended is a state. Hence every mode of mind is active and every mode of body is passive. Now from the fact that every mode of mind is active, it follows that the state of the mind in sensory perception is active, that is, when the mind perceives by means of the senses the mind acts. Insofar as the mind is in perception active and not passive, the mind’s act may be said to be occasioned by the state of the brain. (Note that this approach also would likely have seemed like the obvious one in the context due to its similarity to the Scholastic notion of the ‘agent intellect’ that ‘spiritualizes’ the material species.)

An additional reason why this looks good for Arnauld is that Arnauld is a primitivist about representation: in his view, just as it is the nature of the mind to think, so it is the nature of thought to have an object, and no account of this relation is needed. Hence for Arnauld, there is no problem about how the mind could respond to the state of the brain, since knowing about (perceiving) things like that is just what the mind does.

Arnauld does, however, have another, related problem (and concerns like this are pressed by Malebranche in various places). According to Arnauld, “our thought or perception is essentially reflective upon itself … For I do not think without knowing that I think” (On True and False Ideas, tr. Gaukroger, 71). However, we are not reflectively aware of knowing any state of the brain. It thus remains mysterious how any state of the brain could enter into the explanatory story of thought, whether as an occasional cause or a true one.

(Cross-posted at blog.kennypearce.net)