The Interaction Problem, Substance Dualism, and that one time Descartes gave a terrible excuse when philosophically cornered by a woman
Elisabeth of Bohemia, the Winter Queen, daughter of Frederick V, and the spotlight of this piece, was a contemporary of Rene Descartes who raised pointed (read: s avage ) objections to his substance dualism in their correspondence.
One issue in particular that she touches upon has often been referred to as the interaction problem.
The Interaction Problem: Real Holes and Real Distinctions
The fundamental question underlying what is referred to as the interaction problem is this:
How it is that minds and bodies causally interact so as to produce motion and bodily function, despite being separate and distinct substances?
Causal interaction, so the argument goes, between distinct substances is difficult to conceptualize, if not inconceivable.
This “real distinction” is claimed by Descartes in his Sixth Meditation, through what is commonly referred to as the “Real Distinction” Argument[1]; one being immaterial (the soul, res cogitans), and the other being material (the body, res extensa).
Elisabeth’s position: how do the body and soul really work?
“Tell me” Elisabeth asks, “how the soul of a human being (it being a thinking substance) can determine bodily spirits, in order to bring about voluntary actions” (AT 3:661).
The objection arises at the intersection of two positions:
firstly (1), that there is a real distinction between the soul (or mind) and the body, as claimed by Descartes.
The soul is defined by its activity of thought, is immaterial and non-extended (it does not occupy space). The body, by contrast, is extended (it does occupy space) and material.
secondly (2), that causal interaction appears to be the result of some physical interaction between two bodies. Pphysical interaction between distinct substances (in the way so described by Descartes) is impossible.
What’s really the problem?
The difficulty consists in the observation that all motion (e.g., determined or volitional motion relating to the human being) occurs through and on three conditions:
that bodies act (i.e., move or impel) on one another (i),
that bodies are acted on by one another (ii),
that bodies, with respect to their surface, have a shape and particular quality (iii) which facilitates motion (AT 3:661).
The first two conditions of motion (i, ii) require physical contact, while the third (iii) requires extension ( AT 3:661).
Extension, however, is precluded from the soul by Descartes, as “extension”, strictly speaking, is only a proper of material bodies ( AT 3:661). Physical contact between two distinct substances (one immaterial, the other material), on the other hand, seems to Elisabeth to be incompatible given that these two substances are essentially distinct ( AT 3:661).
For this reason, she asks for a description of the soul’s substance as separate from its activity of thought, so as to better understand how the two interact ( AT 3:661).
Descartes’ response: Primitive notions and ideas
Descartes’ reply consists in an elaboration of what he refers to as “certain primitive notions”which serve as the foundation of knowledge, some of these being “most general” (e.g., being, number), whereas other notions are particular to substance – mind, body, or their joint union ( AT 3:665).
Those notions of the body include, to wit, extension, whence follows notions of shapeand movement; for the soul, this is thought, whence follow notions of perceptionand volition( AT 3:665).
The union of soul and body, however, is known primitively in itself, i.e., that the soul has the power to act on the body and vice versa, producing sensations and passions ( AT 3:665).
The caveat here is the claim that these notions are fundamental and “primitive”, that they can only be known by reference to themselves – they are epistemologically atomic ( AT 3:666).
Descartes’ real response: Don’t worry about it
Elisabeth’s objection, Descartes claims, is at fault in that it attempts to explain the phenomena particular to the unionand its accompanying notion of being embodied, by means of appeal to those notions which are particular to the body ( AT 3:666).
The question of how the soul moves the body cannot be simply explained by appeal to how one body (i.e., by physical contact, motion, or its particular surface) is able to move another ( AT 3:666).
He likewise tries to explain this error by means of an analogy: certain qualities of bodies (e.g., heaviness) are understood through notions corresponding to the soul or body depending on the supposed materiality or immateriality of these qualities ( AT 3:666–7).
In certain instances, these applications are confused in that notions proper to the soul or body are falsely attributed as belonging to one and not the other ( AT 3:667).
In the case of heaviness, though it ought be understood as a property of bodies, even if one were to suppose that it is a real quality (a substance distinct from body, as is sometimes believed), one has no trouble in comprehending how heaviness has the power to move a body towards the center of the earth, a notion particular to bodies (motion), despite the apparent lack of physical contact ( AT 3:667).
The kernel of the argument seems to be this: while it may seem the case that some notions are applicable to certain phenomena (i.e., that heaviness as an immaterial substance that affects bodies), these applications are inherently mistaken (i.e., as heaviness is merely a property of bodies), though seemingly correct, in that they seem to explain what is occurring with respect to these phenomena ( AT 3:667–8).
Why Descartes’ response doesn’t do Elisabeth justice
The response which Descartes gives is inadequate in that it fails to provide an account of how the soul and body act upon one another, which is expressly the focus of Elisabeth’s inquiry ( AT 3:661).
While he does attempt to provide an explanation as to why the exact process is murky and ill-understood, in that the objection itself is expressed in terms which are inimical to a proper understanding of a would-be explanation (i.e., thinking of the interaction of the union in terms of one’s notions as to how bodies interact), his attempt falls short in that it provides no positive account.
It just seeks to elucidate that the entire inquiry is itself directed poorly or inaccurately, that Elisabeth is making what might called a category error.
(So, really, it’s a bad excuse for being philosophically cornered.)
Footnotes:
[1] See his Sixth Meditation for the “Real Distinction” Argument (AT 7:78, CSM 2:54).
Works Cited:
- Princess, Elisabeth of Bohemia, and René Descartes. The Correspondence between Princess Elisabeth of Bohemia and René Descartes, University of Chicago Press, 2007.
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