Am I Certain That I Think?
Descartes wanted to build human knowledge on a foundation of certainty. He thought the Cogito provided an instance of certainty, and many have agreed (Montaigne was there before him). Critics have argued that the conclusion of the Cogito doesn’t follow from the premise (the Lichtenberg objection). However, the premise itself is seldom questioned; it at least is certain, whether or not it entails the existence of a thinker. But is it certain? First, we need to ask what it means: when I say “I think” what proposition am I asserting? Does it mean the same as “I am a thinker”? And does that imply “I am a rational thinker”? Am I asserting that I think rational thoughts? But there are two problems with this interpretation: (a) how can I be certain that my thoughts are rational and (b) how can I be certain that I have thoughts plural? What if there is a brain disease that renders my thought processes irrational while giving me the illusion that they are rational? I can’t rule this out with certainty. And how can I be certain that I have thoughts in the plural given that this will require a series of thoughts over time? I can’t be certain I have had thoughts in the past since memory is fallible, and the existence of future thoughts is even less certain. So, should “I think” be read as “I have a thought now, which may or may not be rational?” But is it possible to have only one thought and it be completely irrational? Would that even be a thought? Thoughts occur in series of linked thoughts (“temporal holism”), and their title to being thoughts surely depends on some degree of conformity to rationality, however minimal. But these requirements are not open to certainty. In addition, thoughts in the ordinary sense have intentionality, but is that open to certainty? Couldn’t I be having thoughts about nothing—how can I be certain that my thoughts are aboutthings? What thought is it that I am supposed to be certain I am having? Is it the thought that it is (say) raining in Miami now? But how can I be certain my thought is about Miami and rain—what if I am a brain in a vat and content externalism is true? Is it the thought that I think (“I think that I think, therefore I am”)? But then we are back with the problem about rationality and thought plurality. It looks as if we need to retreat inwards a step: “I seem to think, therefore I am”. We thus cancel the proposition that I really think and maintain more modestly that I appear to myself to think. This falls far short of the original Cogito in that it concedes that I cannot be certain that I think: that proposition cannot be the premise the Cogito works with. We can gloss “I seem to think” as “I may be thinking now but maybe I am not—it only seems to me that I am”. Is this strong enough to get the conclusion we want? It seems like a very flimsy foundation for erecting a tower of certain knowledge. And if we are to retreat to a “seems” version of the premise, why not say simply “I seem to exist, therefore I exist”? For, if we can’t appeal to an unqualified “I think” but must restrict ourselves to “it seems”, then we may as well do it straightforwardly and honestly—”I seem to myself to exist, therefore I must exist”. But that looks like a straight non-sequitur: how can my existence follow from the mere appearance that I exist? Don’t we need the existence of something real to get anywhere—as in the existence of real thoughts? How can seemingentail being? Certainly, this revised Cogito looks weird and fishy compared to the classic version—hardly self-evidently true. This impression is confirmed by raising another skeptical possibility, namely that we can’t get existence out of seeming existence—out of the mere impression of existence. Nor can we get it out of the mere impression of thoughts as opposed to real thoughts. Suppose you are Meinong and believe in different kinds of being, subsistence and existence: maybe you can derive self-existence from genuine thought-existence, but how can you derive it from mere appearances of existence? Surely subsistence could seem like existence, so it may be that the self you derive from “I seem to exist/think” is just a subsistent entity not an existing one (like a hallucinatory golden mountain that looks real). In order to rule this out you would need to refute Meinong by claiming that all subsisting objects are existing objects—or else the Meinongian will insist that the conclusion could only be that I have some sort of being. In other words, the seeming premise only licenses an inference to “The subject of this seeming has being of some sort”. To be more specific, how can I be certain I am not a fictional character? It can seem to a fictional character that he thinks and exists, but he is not thereby a thinking existing being like you and me (as we believe, at any rate). Or if you hold that fictional characters really have existence, then the new Cogito has to conclude “Either I exist in the real world or I am a character in fiction”—not quite what Descartes was hoping for. The problem is that seeming is too weak to give (real) being, but we can’t justify the original premise that asserts certainty about the existence of thoughts (thinking). Can we assert the existence of real seemings? If so, we might be able to move to real subjects of seemings. But of course, there can be fictional seemings: it can seem to a fictional character that things are thus-and-so. I therefore need a way of showing that my seemings are real, but all I am entitled to is that they seem real. We are now at an argumentative stalemate, whereas the original Cogito at least purports to start from a premise about incontestable reality, viz. the known reality of thoughts and thinking. The idea was that we can know with certainty that thinking really exists and then move from this to the existence of the self. But it now turns out that only a “seems” premise is acceptable, which undercuts the move to an “is” conclusion (“I exist”). So, Descartes needs his version of the Cogito and not the weakened “seems” version: if the argument were equally good under the “seems” interpretation, he could have simply said “I seem to exist, therefore I exist”—which looks like a blatant non-sequitur. But the original version is open to skeptical doubt about the premise itself, not merely about the validity of the inference. The lesson is that trying to base human knowledge on certainty is hopelessly quixotic and should not be attempted (unless we stick with the ordinary man’s use of “certain” and forget about philosophical skepticism). Or to put it differently, an epistemology of science should not be in the business of refuting skepticism. It will only take a sound beating if it chooses to take on the skeptic (like Don Quixote himself fighting foes far more powerful than him). Descartes clearly had problems with his attempt to prove the external world (what with the ontological argument and God’s supposed non-deceptive nature), but in fact the problems begin much further back with his attempt to find at least one indubitable proposition. It is the whole Cartesian project that is at fault. Certainty is a false god.
 This is exactly the situation of two characters in Sophie’s World by Jostein Gaarder (1994): they think they are real but discover that they are characters in someone else’s work of fiction. Fictional characters cannot use the Cogito to prove they are real.
 There is also the problem that in order to know that it seems to me that I exist, or that I seem to have thoughts, my seeming must have intentional content; but how can I be certain that it does, given that this doesn’t depend solely on my inner state? The skeptic will argue that my seeming might not have the content I take it to have, if I am a brain in a vat or sufficiently mentally deranged or confused. Episodes of seeming can be as subject to skepticism as thoughts are with respect to their content. Things are not as simple as Descartes supposed.
 Don Quixote de la Mancha cuts quite a philosophical figure: even after a series of terrible drubbings he refuses to abandon his absurd delusions, despite the entreaties of Sancho Panza (the voice of common sense). He is the living embodiment of human error—of life inside Plato’s cave. Descartes is quixotic in the precise sense that he keeps fighting for his misguided ideals even when he is clearly outgunned by the evil demon; he is too entranced by the romance of complete certainty. There is a nobility to this, but it’s none too realistic.