Illustration from Comparative Zoology, Structural and Systematic : For Use in Schools and Colleges, 1883

Stupidity and wisdom share a mysterious intimacy. Compare them with their parents, ignorance and knowledge. Ignorance is an unwelcome absence, which the acquisition of knowledge expels the way that an influx of matter wipes out a vacuum. In the space of the mind, knowledge abhors ignorance. But stupidity and wisdom are not the measures of one another’s absence. Rather, since they each carry the genes of both their parents, they also contain one another as though in facing mirrors. Stupidity is ignorance that mistakes itself for knowledge; wisdom is knowledge that recognizes itself as ignorance.

No one knows nothing like philosophers. Socrates is alleged to have said, “I know one thing, that I know nothing.” Whether or not the saying truly belongs to Socrates, it articulates a paradox at the core of the problem of knowledge: to know anything for sure—to know that you know something—requires knowing already what it is not to know something. Only by having no illusions about what true knowledge is can you be sure that you know anything. Socrates is ignorant, but he is wise; he knows very well the difference between ignorance and knowledge.

Moreover, in order to know you don’t actually know something, you have to already know what it is for something to be. This has as much to do with how we use language as it does with what we count as reality. Imagine a scenario in which a man believes that he knows that he’s sitting in a wooden chair, but you know that the chair is plastic. You might say that the man doesn’t really know what he thinks he knows, but first you’ll have to be sure just what “wooden” and “plastic” are, and how exactly they’re relevant to the question. This may require knowing about objects and properties and subjects and predicates, which requires already having some general ideas about what things and words are, how they relate to one another, and what they have to do with knowledge. Now imagine that the man believes that he knows he’s sitting in a wooden chair, but you know that the man’s hallucinating, and there really is no chair. Again, you might say that he doesn’t really know what he thinks he knows, but first you’ll need to be sure that the fact that there’s not really a chair is relevant to the question, which requires knowing what reality is and what unreality is and what they have to do with knowledge.

What these scenarios show is that epistemology (the study of knowledge) is intertwined with ontology (the study of being). Insofar as knowledge is always knowledge of something, any claim to knowledge presupposes an understanding of what it is to know (rather than merely believe) and also of what it is for something to be (rather than merely seem). Therefore, in order to know that you know anything—i.e. in order to know something “for certain,” “for real,” “beyond possible (or reasonable) doubt”—you must already know (for certain, for real, etc.) about knowing and being (e.g. how not to mistake ignorance for knowledge and how not to confuse something and nothing). Truth be told, Socrates knows more than one thing. For if he really knows that he knows nothing, he must also know what nothing is.

But perhaps now I’ve gone too far. “Nothing is not something!” my interlocutor exclaims; “You’re letting language confuse you—when Socrates says that he know that he ‘knows nothing,’ he means that he knows that he ‘does not know anything.’ To make an adverb into a predicable subject is nonsense!” My objector is right to be suspicious. “Nothing” just isn’t the sort of thing of which we ought to say that it “is.” If I seem to be suggesting otherwise, then I’m doubly deceived: first about what is and second about what things are called. Perhaps I’m no better off than poor stupid Polyphemus, shouting blindly, “Nobody has blinded me!”

And yet my claim is not that we ought to say that nothing is. My claim is that, under certain circumstances, we must; that the reification of nothing is an inevitable byproduct (because precondition) of any rigorously articulated theory of knowledge, if only to the extent that a concept of “nothing” must accompany whatever general concept of “being” organizes the theory’s ontology. If this reification seems exceptional in the history of epistemology, it is because like Odysseus, “nothing” is wily. Since its presence is prohibited by its very cause, it must take care to escape notice. But nothing’s there.

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It is one of the cruelest ironies of René Descartes’ legacy that he’s better remembered for doubting the world’s existence than for inventing a way of quantifying its abstract architecture (what we still call “Cartesian geometry”) or for formulating mathematically the laws of its visibility (what we now know as Snell’s law of refraction). There are several possible reasons for our amnesia. One might be the relatively recent separation of philosophy, mathematics, and science, but it seems to me that this division merely split the River Lethe into three streams, and that the selective memory of each of the three disciplines flows from a common amnesic source. More important is the fact that “Cartesian skepticism” is commonly misunderstood. To the (debatable) extent that Descartes doubted the existence of the world, he did so in order to demonstrate that the world can be known with the same level of certainty offered by deductive proofs. Truth be told, Descartes was less skeptical than he was rigorously methodical. In Discourse on Method (1637), he explains that he adopted his approach from geometry, in which no proposition is held to be true unless it necessarily follows from a previous proposition or set of propositions that have already been rigorously verified. Descartes consciously followed this method throughout his work in pure mathematics and mathematical science (reaping results in fields as diverse as geometry, music theory, optics, biology, and astronomy), but he would have considered it all for naught if he couldn’t verify the truth of the proposition that the world exists. But perhaps the culprit most responsible for our forgetfulness is Descartes himself, who suppressed his early scientific opus, unambiguously entitled The World [le Monde] (1629-1633), lest it provoke the same reaction from the Church as was provoked by the work of his much admired (and never to be forgotten) contemporary, Galileo.

For Descartes, verifying the world’s existence was a necessary step toward grounding his other findings. The problem belonged to the field of “metaphysics,” the roots, according to the famous image from Principles of Philosophy (1644), of the tree of knowledge (physics—the study of nature—comprises the tree’s trunk; medicine, mechanics, and morality comprise its principle branches.) Descartes staged the application of his method to metaphysics twice, first in Discourse on Method and then again, in much greater detail, in Meditations on First Philosophy (1641). The demonstration has two stages. First he undertakes what he calls in the Meditations the “general demolition” of his opinions, rejecting from his beliefs every proposition that admits of the possibility of being false—everything that can be seriously doubted. During this stage, Descartes takes care to differentiate himself on the one hand from the Pyrrhonian skeptics, who “doubt in order to doubt” and merely “affect being irresolute” (Discourse, 3.6), and on the other hand from the mad, whose distrust of common sense and empirical reality runs rather too deep (Meditations, 13). (In order to be taken seriously as a philosopher, Descartes must refute those who doubt facetiously without allying himself with those who doubt unreasonably.) The second stage involves excavating a set of necessary truths from the rubble and constructing upon their sturdy foundation an edifice of progressively more complex beliefs concerning the mind, the world, and the relation between them. By the end of the demonstration, Descartes takes himself both to have vindicated the basic reliability of everyday experience and to have proven the possibility of attaining certain knowledge about the world through scientific investigation.

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One could read the Meditations as an indirect commentary on the nature of “nothing.” For example, as Descartes shows what must be, he reveals, as though by negation, his concept of what it is not to be. The exposition of any philosophical treatise’s “negative ontology” would be well worth undertaking, but the Meditations offers particular interest for an additional reason. In the Fourth Meditation, Descartes presents a thematic analysis of “nothing” itself—an analysis, moreover, that is both necessary and impossible: necessary because, as Descartes makes clear, the success of the Meditations as a whole depends upon it; impossible because Descartes never gives up his commitment to the fact that “nothing” cannot exist. The Meditations therefore offers us the chance to catch “nothing” in the act and study its wily logic.

I claimed above that epistemology and ontology are intertwined because knowledge is always knowledge of something. The procedure of the Meditations illustrates this from the outset. In the First Meditation, Descartes undertakes “the general demolition” of his opinions, searching by process of elimination for baseline ideas that simply can’t be false. To save time, he goes straight to the source of all of his ideas about the world, his senses. He conjectures that if his senses are fallible, then all of his ideas could in principle be false. And lo and behold, they are. For all he knows he could be mad (though it’s unlikely), or dreaming (always possible), or being deceived by an omnipotent evil demon (why not?). Furthermore, an omnipotent demon could potentially dupe his thoughts in addition to his senses. It’s possible, Descartes claims, that two and three don’t really add up to five and that squares don’t really have four sides, but that a malevolent God only makes it appear so. Accordingly, the constructive phase of the Meditations begins from the implicit premise that if certain knowledge about the world is to be gained, two sources of possible error must be reckoned with. The first is ontological: an object of knowledge apparently given to the mind may in fact not exist. The second is epistemological: even if the given object of knowledge does exist, the mind itself may err in the act of knowing. Overcoming the former will require proving that what seems to be is; overcoming the latter will require proving that what is can be known.

Descartes’ first step is well known. He discovers that there is at least one thing that necessarily escapes both sources of error, one object of knowledge which (1) cannot not be and which (2) the mind cannot err in knowing. This is the knowing subject: Descartes himself. He discovers that he himself cannot not be because the sheer fact of his thoughts (even if all erroneous) necessarily entails that he himself is, as the agent of the thoughts. And he discovers that he cannot err in knowing himself because (at least insofar as his being is his thinking) having any thought about his being (even an erroneous one) just confirms his nature as a res cogitans (“thinking thing”).

Descartes’ discovery of the so-called cogito (the fact that insofar as he thinks, he is) provides the bedrock for his rediscovery of the world, but his demonstration beyond the Second Meditation can be dismissed as a lot of dated, sloppy, theological nonsense: in the Third Meditation he proves God’s existence; in the Fourth Meditation he verifies God’s benevolence, clarifying that the world exists largely as it appears (since God is not a deceiver), and that to the extent that error is possible, it is because the mind makes hasty judgments about the world, foregoing its freedom to abstain from judging things that God hasn’t sufficiently illuminated; in the Fifth and Sixth Meditations he establishes the difference between the mind and the body and also explores their interrelation, sets forth a few new proofs of God’s existence, and elaborates in greater detail how things can be known and how mistaken by the mind. These arguments are indisputably theological, but dismissing them on that basis risks overlooking that Descartes’ “theological” concepts function as necessary elements within a philosophical project whose scope is as ontological as it is epistemological.

One way of bringing out the continuity between the “theological” and “philosophical” dimensions of the Meditations is by tracking the metamorphosis of Descartes’ concept of “nothing.” In the beginning of the Second Meditation, “nothing” means the absolute non-existence of anything. This is what we customarily take “nothing” to mean in its strictest sense: “there’s nothing” means, “it’s not the case that there is anything.” Descartes means precisely this just before he hits upon the necessity of his own existence: “I have convinced myself that there is absolutely nothing in the world [nihil plane in mundo]... Does it now follow that I too do not exist?” When Descartes responds in the negative, he strikes bedrock in what “exists” beyond the world, outside the space where it is possible for there to seem to be something when there is nothing or seem to be nothing when there is something. Descartes’ “I,” qua res cogitans, transcends the world as one of the conditions of possibility of error, and what distinguishes it from everything is that it alone cannot be nothing: “Let [a supremely powerful deceiver] deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something [numquam tamen efficient, ut nihil sim quamdiu me aliquid esse cogitabo].” The thinking subject cannot predicate its own negation without entailing a self-evident contradiction. Of the false thought “I am nothing,” the underlying “I am” will always be true: Sum nihil ergo sum.

When Descartes proves the existence of God in Third Meditation, he merely develops the ontology already latent in his discovery that error’s conditions of possibility lie beyond the world—there must be being beyond what can be nothing. The presentation is in some ways simply dogmatic, which makes it just as hard for modern readers to follow as it is for us to swallow. The dogma is encapsulated in the analogy that Descartes swiftly and unhesitatingly draws between materialist causality and ontological dependence: Just as “something cannot arise from nothing,” so “what is more perfect… cannot arise from what is less perfect.”

The former half of Descartes’ analogy shouldn’t strike us as that strange. For us today, no less than for the ancient materialists whose beliefs the heretical scientists of the Renaissance revived, it’s obvious that nothing can come from nothing: ex nihilo nihil fit. The doctrine merely states that everything has a cause, and yet it was expressly denied by some strains of the Christian tradition because it seemed to impose a limit on God’s omnipotence, contradicting the doctrine of creatio ex nihilo, that God’s power is so boundless that he can create precisely from nothing. Descartes, following Saint Thomas Aquinas, reconciles Aristotelian causality with the tenets of Christian theology by making God the first cause: the original thing from which everything else comes. This solution preserves the law of causality by making God one particular being among others, and at the same time protects God’s omnipotence by making God the general principle of being that maintains everything through His concurrence (thus Descartes says in passing that “the distinction between creation and preservation is only a conceptual one”).

The latter half of Descartes’ analogy, also lifted from Saint Thomas, claims that one of the ways in which every particular thing depends for its being upon the supreme being has to do with the chain of perfection. Any being, to the extent that it is imperfect, depends for its being upon a being that is more perfect. For example, just because a chair is missing a leg doesn’t mean that it’s not a chair—it’s just an imperfect one. This is because being a chair admits of the possibility of lacking certain predicates (like “four-legged”) with respect to the perfect (in this case, four-legged) chair to which all of the predicates would actually belong. Only with respect to a complete being could anything be recognized as lacking something.

In light of the dogma of ontological dependence, Descartes’ argument is simple: If anything imperfect exists, there must also exist a supreme being at the upper limit of the chain of perfection. Since Descartes is assured of his own existence, and knows, moreover, that doubt itself—as a kind of lack—is an imperfection, he deduces that a supreme being must also exist. On its own, the argument seems rather thin. But we must trust that Descartes believes himself to have demonstrated the necessary existence of God with the same certainty that he believes himself to have demonstrated the necessity of his own existence, which, at least in its basic form, we’re probably comfortable granting him.

The similarity between the two demonstrations comes out more clearly if we remember that Descartes’ proof of his own existence was just as “ontological” as his proof of God: what distinguishes the “I” from any given object in the world is that the “I” cannot predicate its own negation without entailing a contradiction. Unlike everything, “I” cannot be nothing; to it exclusively belongs the predicate of necessary existence. It is just the same with God, but on a greater scale. To the extent that the “I,” though in possession of the predicate of necessary existence, nevertheless lacks the set of predicates that would make it perfect, infinite, absolutely complete in every possible respect, etc., it could only recognize such to be the case by virtue of the existence of the perfect, infinite, etc., being called “God”: I can’t be nothing, therefore I am; I can’t be everything, therefore God is.

The fact that “God” is an ontological concept that coheres with the precepts and strategies of the Meditations as a whole rather than an imported dogma that spoils an otherwise rigorous project comes into starker relief when Descartes introduces a second concept of “nothing.” The original “nothing,” as the absolute non-existence of beings within the world, turned out not to cover the field of all possible beings: “I” cannot be nothing, which is to say, the “I” participates in a higher order of being than those to which the predicates “is nothing” or “does not exist” can apply. When Descartes formulates explicitly the nature of this higher order of being, which is actually an axis of being whose upper limit is the supreme being called “God,” he at the same time admits into his ontology a corresponding concept nothing: absolute non-being at the lowest limit of imperfection, incompleteness, and lack.

Since by definition, God has every positive predicate to its fullest possible degree—omnipotence, unbounded benevolence, etc.—when Descartes inquires anew into the transcendental cause of his erroneous thoughts in the Fourth Meditation, it is this other “nothing” that he inculpates:

...I know by experience that I am prone to countless errors. On looking for these cause of errors, I find that I posses not only a real and positive idea of God, or a being who is supremely perfect, but also what may be described as a negative idea of nothing, or of that which is farthest removed from perfection [ut ita loquar, nihili, sive ejus quod ab omni perfectione summè abest, negativam quondam ideam]. I realize that I am, as it were, something intermediate between God and nothing, or between supreme being and non-being [me tanquam medium quid inter Deum & nihil, sive inter summum ens et non ens ita esse constitutum]: my nature is such that in so far as I was created by the supreme being, there is nothing in me [nihil quidem in me sit] to enable me to go wrong or lead me astray; but in so far as I participate in nothing or non-being [de nihilo, sive de non ente, participo], that is, in so far as I am not myself the supreme being and am lacking in countless respects, it is no wonder that I make mistakes.

This solution absolves God of responsibility for the possibility of error without restricting his power, but its price in addition to stipulating of two distinct meanings of “nothing”: it’s is nothing he got from God, but rather something he got from nothing.

Some English translations of the Meditations translate “nihil” in this particular usage as “nothingness,” a choice which is perhaps justified by Descartes’ distinction between “de rien” and “du néant,” which appears in an analogous context in Discourse on Method. That these two terms should appear in a text whose professed intention is to break with scholastic dogma is no less interesting than the fact that no such simple opposition appears in the text dedicated to the Theological Faculty of the Sorbonne. In the Fourth Meditation, Descartes is careful to resist reifying “nothing,” but for the paradoxical reason that by its very nature, transcendental “nothing”—the very condition of the possibility of error—cannot exist. Since transcendental “nothing” opposes God in every respect, “necessarily non-existent” is among its defining predicates—that is, insofar as it can properly be said “to be” at all.

This difficult claim is crucial for Descartes’ project because only by absolutely separating “nothing” (as the cause of the possibility of error and falsity) from God (as the cause of the possibility of knowledge and truth) can he avoid doubting the claim—provisionally adopted in the Second Meditation and verified at the end of the Fourth—that whatever presents itself to his perception “very clearly and distinctly” (illuminated by “natural light”) must be true. In order to maintain this separation, Descartes repeatedly renames the abhorrent cause in an effort to maintain its absolute separation from the sphere of God’s beneficent presence without delimiting his reach. The “nothing” that Descartes participates in, becomes the “defect” in him, which becomes his “lack,” which becomes a “deprivation,” which becomes a “privation.”

These acts of renaming aim to resolve with greater and greater precision the relation of the cause of error to the cause of knowledge, but with each substitution, Descartes runs into the same problem: either “nothing” is the cause of error, which seems to compromise God’s omnipotence, or “nothing” is nothing, which seems to compromise his beneficence. To the extent that Descartes fails to determine adequately the relation between supreme being and absolute nothing (as he must), he makes of his failure of reason a victory of faith. Indeed, each time that Descartes nears this aporia, he performs a rather graceful circumlocution. First, in accordance with the topos of religious humility, Descartes converts the logical impasse into a veritable sign of God’s incomprehensibility:

As I reflect on these matters more attentively, it occurs to me first of all that it is no cause for surprise if I do not understand the reasons for some of God’s actions; and there is no call to doubt his existence if I happen to find that there are other instances where I do not grasp why or how certain things were made by him.

In order to pass over the ontological problem of nothing, Descartes doubts his doubt.

Further in the analysis, after tracing the cause of error back to the misuse of the will, Descartes runs into the same problem. How could God permit the will to be misused without compromising his benevolence or his omnipotence? Descartes deftly subverts this logical objection by responding to it as though it were an expression of indignation. Instead of acknowledging the question of how God could have granted his privation (in principle), Descartes persuades himself not to be ungrateful for what God granted him (in fact).

And I have no cause for complaint on the grounds that the power of understanding or the natural light which God gave me is no greater than it is; for it is in the nature of a created intellect to be finite. Indeed, I have reason to give thanks to him who has never owed me anything for the great bounty that he has shown me, rather than thinking myself deprived or robbed of any gifts he did not bestow.

A rhetoric of gratitude enables Descartes to count his privation as nothing so as not to have to account for its cause. He achieves this by figuring his finitude as a gift rather than as a theft, a surplus rather than a deficit, a presence rather than an absence. The metaphor entirely effaces finitude’s negativity, leaving a remainder of exactly nothing. When the prayer is over Descartes gives the final count: “the privation…does not in any way require the concurrence of God” because it is “not a thing” and “should not be called a privation but simply a negation.”

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Descartes published the Meditations with a collation of Objections and Replies, that afford the reader the chance to witness his willingness to engage in dialogue with his interlocutors. The most famous of the printed objections articulated what has come to be known as the “Cartesian Circle”: the claim that Descartes proof of his own existence tacitly presupposes knowledge of God (that he exists, that he is beneficent, omnipotent etc.), which are needed in order to validate the criterion of clearness and distinctness that enables Descartes to attain certain knowledge of anything. It would be more precise, if less self-evident, to object that Descartes presupposes knowledge of nothing: namely, that it is nothing.

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