The Identity of Thought and Object in Spinoza RICHARD E. AQUILA Two LINES OF THOUGHT converge in Spinoza's doctrine of the identity of thought and its object. Only one of them is contained in the "official" presentation of Spinoza's argument. It lies in the general conception he offers of the relationship among the various attributes of reality. Despite Spinoza's claims, however, the latter conception does not require acceptance of the doctrine in question. Furthermore, Spinoza's own response to objections concerning that doctrine's compatibility with his general conception of the attributes shows that the relation between thought and its object cannot be regarded as an instance of the "identity" obtaining among the attributes generally. Nevertheless, it is possible to see why Spinoza's doctrines led him to see an "identity" in both cases. Thus we may also see how two distinct lines of reasoning became blurred into one in his thought, to the inevitable advantage of the official presentation. The second--"unofficial"--motivation stems from a certain Cartesian assumption concerning the nature of thought and its object, combined with Spinoza's crucial departure from a doctrine essential to Descartes's own implementation of that assumption. The resulting conception, it will be interesting to see, anticipates a view elaborated in Sartre's Being and Nothingness. I. The Ethics 1 defends a remarkably original view concerning the relationship between bodily and mental events. Bodily events are (qua bodily) "modes" of the attribute extension; mental events are (qua mental) modes of thought. But substance thinking and substance extended are one and the same substance, which is now comprehended under this attribute and now under that. Thus, also, a mode of extension and the idea of that mode are one and the same thing expressed in two different ways.... therefore, whether we think of Nature under the attribute of extension, or under the attribute of thought or under any other attribute whatever, we shall discover one and the same order or one and the same connection of causes, that is to say, in every case the same sequence of things. (2, 7, note) Thus Spinoza defends a form of the "identity theory" with respect to mind and body. Since the human mind is a system of thoughts constituting an "idea" of the body (2, 10-13), a person's mental events are, regarded under the attribute of extension, the ' Spinoza Opera, ed. Carl Gebhardt,4 vols. (Heidelberg:CarlWinter, 1925),vol.2; trans. W. H. White (revisedby A. H. Stirling),ed. JamesGutmann(NewYork:Hafner PublishingCo., 1949).Referencesto Ethica appear parentheticallyby part number followedby propositionnumberin the text. [271] 272 HISTORY OF PHILOSOPHY very same events as those that constitute that person's body. However, Spinoza's view differs in two ways from some other forms of the identity theory. First, most recent defenses of that theory maintain that the concepts involved in a consideration of material events as mental are subject to a "topic-neutral" analysis. That is, what those concepts express concerning the events in question can be analyzed in terms that involve a conception neither of specifically mental nor of specifically material events. 2 On the other hand, the concepts involved in regarding those events in material terms cannot be analyzed solely in terms involving no specifically material concepts. To this extent there is, on such a view, a certain priority accorded to the material conception of the events in question. Spinoza's view rejects this priority: neither way of regarding events can be explained in more basic terms (1, 10). The second respect in which Spinoza 's version differs from other versions of the "identity theory" concerns Spinoza's claim that those events that, regarded materially, constitute a person's body are not simply the same events as those that, regarded mentalistically, constitute a person's mind. In addition, the events regarded in the former of these ways are the objects of the very ideas with which they are "identical": "a mode of extension and the idea of that mode are one and the same thing expressed in two different ways." Philosophers other than Spinoza have also espoused theories of mind-body identity embodying the first of these features...