Philosophy Research Archives

Volume 13, 1987/1988

Descartes’ Quartum Quid

My goal is to illustrate Descartes’ reliance on two quite different and competing interpretations of objective reality by explaining how each is used in defending his causal axioms. The initial criticism comes from Caterus (and is later taken up by Gassendi) who charges that Descartes makes it appear as if the thought in its objective aspect (the intentional entity) is really distinct from the thought qua modification of the mind (i.e., the thought in its formal aspect). This implies that the object-of-the-thought is actually distinct from the thought-of-the-object in which case, (a) Descartes cannot account for the purported relation between the two, and (b) the intentional entity must exemplify properties which belong neither “immaterially” to mental substance nor concretely to physical substance. Descartes rejects Caterus’ assessment of his position: he has not introduced a fourth kind of real entity into the causal order distinct from the mind, its modifications, and the physical object thought of. However, in responding to Caterus, Descartes implicitly appeals to a Suarezian theory of intentionality in which reference to the ostensibly separate reality of the objective entity is reducible to the formal concept: the thought-of-the-object is not really distinct from the object-of-thought. Clearly, Descartes cannot explicitly use the Suarezian theory because it relies on a system of causal explanation (the doctrine of the species “flitting through the air”) which Descartes rejects on scientific grounds. I shall argue that Descartes is committed to a notion of the “form” of the mind, viz., a modification of mind, which should allow for a non-relational modeling of the thought qua modification of the mind and its intentional object, but that he cannot consistently attribute to mental acts enough structure to support his theory.