Spiritus sanctus non est skepticus—"The Holy Spirit is not a skeptic." So Luther rebuked Erasmus of Rotterdam for his expressed disdain for making sure assertions. Luther roared, "The making of assertions is the very mark of the Christian. Take away assertions and you take away Christianity. Away now, with the skeptics!"
Doubt is the hallmark of the skeptic. The skeptic dares to doubt the indubitable. Even demonstrable proof fails to persuade him. The skeptic dwells on Mt. Olympus, far aloof from the struggles of mortals who care to pursue truth.
But doubt has other faces. It is the assailant of the faithful striking fear into the hearts of the hopeful. Like Edith Bunker, doubt nags the soul. It asks "Are you sure?" Then, "Are you sure you're sure?"
Still doubt can appear as a servant of truth. Indeed it is the champion of truth when it wields its sword against what is properly dubious. It is a citadel against credulity. Authentic doubt has the power to sort out and clarify the difference between the certain and the uncertain, the genuine and the spurious.
Consider Descartes. In his search for certainty, for clear and distinct ideas, he employed the application of a rigorous and systematic doubt process. He endeavored to doubt everything he could possibly doubt. He doubted what he saw with his eyes and heard with his ears. He realized that our senses can and do often deceive us. He doubted authorities, both civil and ecclesiastical, knowing that recognized authorities can be wrong. He would submit to no fides implicitum claimed by any human being or institution. Biographies usually declare that Descartes was a Frenchman but his works reveal that he was surely born in Missouri.
Descartes doubted everything he could possibly doubt until he reached the point where he realized there was one thing he couldn't doubt. He could not doubt that he was doubting. To doubt that he was doubting was to prove that he was doubting. No doubt about it.
From that premise of indubitable doubt, Descartes appealed to the formal certainty yielded by the laws of immediate inference. Using impeccable deduction he concluded that to be doubting required that he be thinking, since thought is a necessary condition for doubting. From there it was a short step to his famous axiom, cogito ergo sum, "I think, therefore I am."
At last Descartes arrived at certainty, the assurance of his own personal existence. This was, of course, before Hume attacked causality and Kant argued that the self belongs to the unknowable noumenal realm that requires a "transcendental apperception" (whatever that is) to affirm at all. One wonders how Descartes would have responded to Hume and Kant had he lived long enough to deal with them. I have no doubt that the man of doubt would have prevailed.
There were clearly unstated assumptions lurking beneath the surface of Descartes' logic. Indeed there was logic itself. To conclude that to doubt doubt is to prove doubt is a conclusion born of logic. It assumes the validity of the law of non-contradiction. If the law of non-contradiction is not a valid and necessary law of thought, then one could argue (irrationally to be sure) that doubt can be doubt and not be doubt at the same time and in the same relationship.
The second assumption was the validity of the law of causality (which, in the final analysis, is merely an extension of the law of non-contradiction). Descartes could not doubt that an effect not merely may, but must have an antecedent cause. Doubt, by logicial necessity, requires a doubter, even as thought requires a thinker. This is nothing more than arguing that action of any kind cannot proceed from non-being. Hume's skepticism of causality was cogent insofar as he brilliantly displayed the difficulty of assigning a particular cause to a particular effect or event. But not even Hume was able to repeal the law of causality itself. It is one thing to doubt what the cause of a particular effect is, it is quite another to argue that the effect may have no cause at all. This is the fundamental error countless thinkers have made since Hume. I once read a critical review of Classical Apologetics in which the able and thoroughly Christian reviewer observed, "The problem with Sproul is that he refuses to acknowledge the possibility of an uncaused effect."
I wrote to my reviewing collegue and pleaded guilty to the charge. Mea culpa. I do refuse to acknowledge even the most remote possibility of an uncaused effect. I have the same obstreperous stubbornness for circles that are not round and for married bachelors. I asked my friend to cite but one example, real or theoretical, of an uncaused effect and I would repent in dust and ashes. I'm still waiting for his reply. If he reads this perhaps it will jog his memory and induce him either to deliver the goods or admit his glaring error.
I certainly allow for uncaused being, namely God, but not for uncaused effects. An uncaused effect is an oxymoron, a veritable contradiction in terms, a statement patently and analytically false, which Descartes could refute in his Dutch oven without the benefit of empirical testing.
So how does this affect the Christian in his struggle with the doubts that assail faith? The content of Christianity, in all its parts, cannot be reduced simplistically to Cartesian syllogisms. The lesson we learn from Descartes is this: when assailed by doubt, it is time to search diligently for first principles that are certain. We build upon the foundation of what is sure. This affects the whole structure of apologetics. It is a matter of order. It seems astonishing to the lay person that anybody would go to the extremes Descartes insisted simply to discover that he existed. What could be more self-evident to a conscious being than one's own self-consciousness? But Descartes was not on a fool's errand. In a world of sophisticated skepticism, Descartes sought certainty for something that could serve as a foundation for much, much more. He moved from the certitude of self-consciousness to the certitude of the existence of God, no small matter for the doubt-ridden believer. Descartes and others like him understood that to prove the existence of God is prior to affirming the trustworthiness of Scripture and the birth and work of the person of Christ. Once it is certain that God exists and reveals Himself in Scripture, there is ground for a legitimate fides implicitum.
But the order of the process to destroy doubt is crucial. For example, the miracles of the Bible cannot and were never designed to prove the existence of God. The very possibility of a miracle requires that there first be a God who can empower it. In other words, it is not the Bible that proves the existence of God, it is God who through miracle attests that the Bible is His word. Thus proven, to believe the Bible implicitly is a virtue. To believe it gratuitously is not.
The most important certainty we can ever have is the foundational certainty of the existence of God. It is this matter that prompted Edwards to declare: "Nothing is more certain than that there must be an unmade and unlimited being" (Miscellany #1340).
On this bedrock of certainty rests the promises of that unmade, unlimited Being. On these promises we rest our faith. Doubting served Descartes well, but Edwards knew that ultimately, it is dubious to doubt the indubitable.
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