Just for fun, I’m publishing this section of a much longer paper I wrote back in my graduate school days. Re-reading it, I am struck by the way in which Descartes’ “Cartesian anxiety” and the search for certainty is alive and well, perhaps above all in the Church.
Writing around the time of Galileo’s skirmishes with the Inquisition, René Descartes (1596-1650) appropriated the scientific concern for method and its reliance upon mathematics for philosophy. In his Discourse on Method (1637), Descartes discloses his lifelong search for “clear and positive” knowledge, a search that led him through the study of classical languages and literature to theology and philosophy, and finally to the resolution to adhere to “the plumb-line of reason” alone [Discourse on Method and The Meditations, translated by F. E. Sutcliffe (Penguin Books, 1968), pp. 29 & 37]. Early in life, Descartes was fascinated by mathematics “because of the certainty and self-evidence of its reasonings” [ibid., p. 31]. But no such apodictic knowledge could be found in theology and philosophy. Descartes prudently avoids detailed discussion of the limitations of theology, preferring instead to confess his own inability adequately to understand revelation.
He does, however, launch a frontal attack on philosophy. In particular, Descartes faults philosophy for its speculative diversity. Instead of securing certain knowledge (episteme), philosophy tends to exalt mere opinion (doxa) to a privileged epistemological status it cannot possibly maintain. Since no two philosophers reach agreement with each other, a mere glance at the history of philosophy suffices to prove that it has failed to provide self-evident truths. The philosophers’ speculative endeavors are just so many “magnificent palaces built on nothing but sand and mud” [p. 31]. Descartes concludes that such “shifting foundations” can never prove adequate to the task of obtaining certainty [p. 32]. So if one cannot rely upon the authority of philosophy or theology (and, by implication, the Church) to obtain secure, objective knowledge, how can anyone ever know anything with certainty?
Descartes’ answer consists in the attempt properly to ground knowledge in a “true method” [p. 40]. Such a method must take its point of departure in the very state of uncertainty in which Descartes finds himself as he reviews the inadequacies of philosophy and theology. And so Descartes begins with the proposition, “I doubt.” He turns this proposition into a rigorous ascetic program of self-denial. Maintaining doubt as a regulative methodological principle entails denying the temptation to indulge in unwarranted beliefs as though they constitute knowledge.
In principle, nothing is exempt from radical doubt. Descartes writes that this methodological starting point means “reject[ing] as being absolutely false everything in which I could suppose the slightest reason for doubt” [p. 53; emphasis added]. The outcome of methodically subjecting everything to doubt, Descartes finds, is the realization that there is someone doubting. Descartes cannot doubt this without self-contradiction. Hence, he adopts the proposition “I think, therefore I am” as “the first principle” from which all other certain knowledge may be deduced [pp. 53 & 54; Descartes’ emphasis]. This proposition merits the status of a first principle because it meets the criteria of knowledge for Descartes: it is clear and distinct, and thus beyond doubt.
Descartes’ rejection of the external authorities of Church teachings and scholarly opinions as determinative of knowledge leads him to turn to his own subjectivity as the locus of authority. Through the introspective gaze of radical doubt, he uncovers the first principle that allows him, in accordance with the model of mathematical demonstration, to deduce the further certainties of thinking, being, and by extension, the existence of God. Each subsequent step follows carefully and logically from the preceding step. If the first step in the chain of reasoning is apodictically certain, then the conclusions are likewise apodictically certain. So the chain of reasoning as a whole is only as strong as the first link in the chain. Only that first link guarantees secure foundations for knowledge.
The very strength of Descartes’ demonstrative method embodies its weakness. This accounts for why the American pragmatic philosopher Richard J. Bernstein detects what he calls a “Cartesian Anxiety” in Descartes’ Meditations on First Philosophy [Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis (University of Philadelphia Press, 1988), p. 16]. Bernstein observes that Descartes’ quest for certainty embodies an irresolvable tension. On the one hand, Descartes’ arguments revel in the confidence of someone who has, indeed, found grounds for certainty. But on the other hand, his prose style and rhetoric imply that the dogs of radical doubt unleashed by the flight from authority never seem to stop nipping at the philosopher’s heels. Bernstein is worth quoting at length on the lingering anxiety at the heart of Descartes’ method:
If we practice these spiritual exercises earnestly, as Descartes urges us to do, if we follow the precarious stages of this journey without losing our way, then we discover that this is a journey that is at once terrifying and liberating, culminating in the calm reassurance that although we are eminently fallible and subject to all sorts of contingencies, we can rest secure in the deepened self-knowledge that we are creatures of a beneficent God who has created us in his image. The terrifying quality of the journey is reflected in the allusions to madness, darkness, the dread of waking from a self-deceptive dream world, the fear of having “all of a sudden fallen into a very deep water” where “I can neither make certain of setting my feet on the bottom, nor can I swim and so support myself on the surface,” and the anxiety of imagining that I may be nothing more than a plaything of an all-powerful demon. ... With a chilling clarity Descartes leads us with an apparent and ineluctable necessity to a grand and seductive Either/Or. Either there is some support for our being, a fixed foundation for our knowledge, or we cannot escape the forces of darkness that envelop us with madness, with intellectual and moral chaos [pp. 17 & 18].
Bernstein argues that Descartes never fully overcomes this anxiety. In the absence of any other authority, the correct method for grounding knowledge should insure the integrity and soundness of inquiry by exorcising the demonic side of radical doubt. But perhaps the demons are only held in check. If the first link in the chain of reasoning and the following steps are certain, then the conclusion carries more authority than all the combined voices that have ever uttered mere opinions. The true method keeps the demons of radical doubt on a leash so that they cannot turn on their master, overpowering the rational faculties and casting the mind into the abyss. But doubt’s radical character can always raise the lingering uncertainty of having made a mistake somewhere along the chain of reasoning, or even (God forbid!) at the very outset.
Given the time in which Descartes wrote, a period in which the safest way to reason publicly about truth meant starting with dogmas and the existence of God, his method of starting with radical doubt and concluding with God was revolutionary. Even if subsequent thinkers found his method problematic, Descartes had at least raised the possibility that one could legitimately doubt inherited traditions and still achieve the certainty of knowledge. Indeed, Descartes bequeathed to subsequent generations the permission to doubt. Instead of conventional authorities, the “natural light of our understanding,” or the exercise of internal reason, would suffice [Descartes, p. 34]. And so Descartes believed that he had reconciled the mathematical mode of demonstration so central to the new science with belief in the soul and in God.
In company with Francis Bacon, his empiricist counterpart in England, Descartes held that the proper method of inquiry would guarantee genuine knowledge and truth. Significantly, however, Descartes’ methodological revolution does not extend to his basic conception of truth. He still views truth in classical terms. Truth is simple. Truth is perfect. Truth forms a unity. Like the conclusion of a geometrical proof, truth is self-authenticating. Thus, Descartes declares that “as there is only one truth of each thing, whoever finds it knows as much about the thing as there is to be known” [p. 43]. And so the Cartesian project shifts the locus of authority away from external authorities to the internal authority of human reason. Instead of truth being imposed from without, truth is imposed from within by the individual’s use of reason.
Viewed through the lenses of mathematics’ aesthetic qualities of elegance and simplicity, this conception of truth complements and provides rational grounding for Descartes’ acceptance of the classical Simplicity Doctrine of God. This doctrine holds that God’s existence and God’s essence form a unity such that God does not merely possess attributes such as goodness, mercy, justice, love, etc.; God is good, merciful, just, loving, etc. Furthermore, all of these properties form a unity. Thus, God always acts with one will for the good of human beings. Descartes’ reliance upon a mathematical model of deductive reasoning confirms the Simplicity Doctrine, which in turn reaffirms that God cannot deceive human beings like some kind of demon.
The difference between Descartes and the classical view is that now human beings must provide unassailable evidence for this doctrine on their own without recourse to authorities external to the individual’s reason. This includes appeals to official doctrine and to scripture (although Descartes would probably insist that his views do not contradict these authorities). Inadvertently, this opens the door to the possibility that if the powers of human reason cannot meet the task of providing this evidence, then belief in such a God will be swept away beneath the demonic currents of unmitigated doubt and skepticism, drowning human beings in the sea of uncertainty.
 Descartes’ acceptance of the Simplicity Doctrine is clearly stated in Meditations on First Philosophy when he writes: “ … the unity, simplicity, or inseparability of all the properties of God, is one of the principal perfections that I conceive to be in him” [p. 129]. Of course, it is a different issue as to whether or not Descartes’ God, affinities with classical theism aside, merits worship or warrants any confession of faith.