One of the deepest and most abiding of Pierre Bayle's philosophical preoccupations concerns the possibility of rational theology, or more specifically, the extent to which unaided reason is competent to secure the fundamental tenets of orthodox Christianity. Doubtless the most familiar aspect of this intellectual 'obsession' is his tenacious criticism of traditional solutions to the problem of evil. Yet these discussions represent only one facet of Bayle's engagement with the complex issues involved in the question of rational theology. Throughout the Historical and Critical Dictionary and in subsequent works, three issues in particular figure prominently in Bayle's discussions: the existence of a transcendent, immaterial God, the immortality of the soul, and mind-body dualism. These topics are, of course, interrelated, and Bayle rarely treats them in complete isolation. Although his official position is explicitly fideistic, there is reason to believe that Bayle was a reluctant skeptic, who was naturally sympathetic with the metaphysical dogmatism of Descartes and Malebranche. Indeed, for Bayle, the great promise of Cartesianism is its seeming ability to secure the distinctness of mind and body, which is in turn the only possible metaphysical foundation not only for personal immortality, but for the conception of God as a transcendent creator of the universe.
At the end of the seventeenth century this constellation of issues is nowhere more urgently brought to the fore than by Locke's agnosticism concerning the possibility of thinking matter. The controversy with Bishop Stillingfleet, which Locke's suggestion helped to engender, was a major intellectual event in Europe, and one that Bayle followed avidly. In the course of this debate, as in the Essay itself, Locke invoked the [End Page 511] possibility of superaddition in an attempt to secure the existence of an immaterial transcendent God while holding open the possibility that created, finite material substances might be endowed with the power of thought. In the first part of this paper I shall examine two important arguments that Bayle develops against Lockean superaddition. Taken together these arguments constitute a sophisticated critique of the conceptual coherence of Locke's position. I shall go on to argue that for Bayle himself the true threat to rational theology lies less in the claim that matter might think by way of superaddition (a view that Bayle sees as untenable), than in the growing move to abandon the Cartesian analysis of matter as res extensa. More specifically I shall argue that for Bayle, if we once reject the view that extension is the essence of matter, we are left with no rational basis for upholding substance dualism. To renounce our clear and distinct idea of extension as the essence of matter is tantamount in Bayle's eyes to opening the door to materialistic atheism.
I Lockean Superaddition in the Dictionary
In a familiar passage from his discussion of the extent and limits of human knowledge, Locke denied that we have demonstrative knowledge of the immateriality of the mind. He wrote:
We have the Ideas of Matter and Thinking, but possibly shall never be able to know, whether any mere material Being thinks, or no; it being impossible for us, by the contemplation of our own Ideas, without revelation, to discover, whether Omnipotency has not given to some Systems of Matter fitly disposed, a power to perceive and think, or else joined and fixed to Matter so disposed, a thinking immaterial Substance: It being, in respect of our Notions, not much more remote from our Comprehension to conceive, that GOD can, if he pleases, superadd to Matter a Faculty of Thinking, than that he should superadd to it another Substance, with a Faculty of Thinking....1
Locke's conception of superaddition has proved notoriously difficult to interpret, in part because it involves a host of controversial issues that lie at the heart of his philosophy — the doctrine of real essences, the bare substratum account of substance, and the relative strength of his commitment to mechanism. Although I cannot address this thorny interpretive question here, it is fair to say that in the recent literature two broad lines of interpretation have emerged. The first, which we might call the [End...