Thinking, no doubt, plays an enormous role in every scientific enterprise, but it is the role of a means to an end; the end is determined by a decision about what is worthwhile knowing, and this decision cannot be scientific. Moreover, the end is cognition or knowledge, which, having been obtained, clearly belongs to the world of appearances; once established as truth, it becomes part and parcel of the world. Cognition and the thirst for knowledge never leave the world of appearances altogether; if the scientists withdraw from it in order to "think," it is only in order to find better, more promising approaches, called methods, toward it. Science in this respect is but an enormously refined prolongation of common-sense reasoning in which sense illusions are constantly dissipated just as errors in science are corrected. The criterion in both cases is evidence, which as such is inherent in a world of appearances. And since it is in the very nature of appearances to reveal and to conceal, every correction and every dis-illusion "is the loss of one evidence only because it is the acquisition of another evidence in the words of Merleau-Ponty.69 Nothing, even in science's own understanding of the scientific enterprise, guarantees that the new evidence will prove to be more reliable than the discarded evidence.
The very concept of an unlimited progress, which accompanied the rise of modern science, and has remained its dominant inspiring principle, is the best documentation of the fact that all science still moves within the realm of common sense experience, subject to corrigible error and deception. When the experience of constant correction in scientific research is generalized, it leads into the curious "better and better," "truer and truer," that is, into the boundlessness of progress with its inherent admission that the good and the true are unattainable. If they were ever attained, the thirst for knowledge would be quenched and the search for cognition would come to an end. This, of course, is unlikely to happen, in view of the enormous amount of the unknown, but it is quite likely that particular sciences may reach definite limits of what is knowable to man. Yet the point is that the modern idea of progress implicitly denies such limitations. Unquestionably the notion of progress was born as the result of the tremendous advances of scientific knowledge, a veritable avalanche of discoveries, in the sixteenth and seventeenth centuries, and I think it quite possible that it was the relendessness inherent in sheer thinking, whose need can never be assuaged, that, once it had invaded the sciences, drove the scientists to ever-new discoveries, each one giving rise to a new theory, so that those caught in the movement were subject to the illusion of a never-ending process—the process of progress. Here we should not forget that the later notion of an unending perfectibility of the human species, so prominent in the eighteenth-century Enlightenment, was absent from the sixteenth and seventeenth centuries' rather pessimistic evaluation of human nature.
One consequence, however, of this development seems to me obvious and of considerable importance. The very notion of truth, which somehow had survived so many turning-points of our intellectual history, underwent a decisive change: it was transformed or, rather, broken down into a string of verities, each one in its time claiming general validity even though the very continuity of the research implied something merely provisional. This is a strange state of affairs. It may even suggest that if a given science accidentally reached its goal, this would by no means stop the workers in that field, who would be driven past their goal by the sheer momentum of the illusion of unlimited progress, a kind of semblance rising out of their activity.
The transformation of truth into mere verity results primarily from the fact that the scientist remains bound to the common sense by which we find our bearings in a world of appearances. Thinking withdraws radically and for its own sake from this world and its evidential nature, whereas science profits from a possible withdrawal for the sake of specific results. In other words, it is common-sense reasoning ultimately that ventures out into the realm of sheer speculation in the theories of the scientists, and the chief weakness of common sense in this sphere has always been that it lacks the safeguards inherent in sheer thinking, namely, thinking's critical capacity, which, as we shall see, harbors within itself a highly self-destructive tendency. But to go back to the assumption of unlimited progress, the basic fallacy was early discovered. It is well known that not progress per se, but the notion of its limitlessness would have made modern science unacceptable to the ancients. It is less well known that the Greeks had some reason for their "prejudice" against the infinite. (Plato discovered that everything permitting of a comparative is by nature unlimited, and limitlessness was to him as to all Greeks the cause of all evils.70 Hence, his great confidence in number and measurement: it sets limits on what of itself [pleasure, for instance] "does not and never will contain and derive from itself either beginning [archē] or middle or end [telos]."71 )
That modern science, always hunting for manifestations of the invisible—atoms, molecules, particles, cells, genes—should have added to the world a spectacular, unprecedented quantity of new perceptible things is only seemingly paradoxical. In order to prove or disprove its hypotheses, its "paradigms" (Thomas Kuhn), and to discover what makes things work, it began to imitate the working processes of nature. For that purpose it produced the countless and enormously complex implements with which to force the non-appearing to appear (if only as an instrument-reading in the laboratory), as that was the sole means the scientist had to persuade himself of its reality. Modern technology was born in the laboratory, but this was not because scientists wanted to produce appliances or change the world. No matter how far their theories leave common-sense experience and common-sense reasoning behind, they must finally come back to some form of it or lose all sense of realness in the object of their investigation. And this return is possible only via the man-made, artificial world of the laboratory, where that which does not appear of its own accord is forced to appear and to disclose itself. Technology, the "plumber's" work held in some contempt by the scientist, who sees practical applicability as a mere by-product of his own efforts, introduces scientific findings, made in "unparalleled insulation ... from the demands of the laity and of everyday life,"72 into the everyday world of appearances and renders them accessible to common-sense experience; but this is possible only because the scientists themselves are ultimately dependent on that experience. Seen from the perspective of the "real" world, the laboratory is the anticipation of a changed environment; and the cognitive processes using the human abilities of thinking and fabricating as means to their end are indeed the most refined modes of common-sense reasoning. The activity of knowing is no less related to our sense of reality and no less a world-building activity than the building of houses.
The faculty of thinking, however, which Kant, as we have seen, called Vernunft (reason) to distinguish it from Verstand (intellect), the faculty of cognition, is of an altogether different nature. The distinction, on its most elementary level and in Kant's own words, lies in the fact that "concepts of reason serve us to conceive [begreifen, comprehend], as concepts of the intellect serve us to apprehend perceptions" ("Vernunftbegriffe dienen zum Begreifen, wie Verstandesbe-griffe zum Verstehen der Wahmehmungen").73 In other words, the intellect (Verstand) desires to grasp what is given to the senses, but reason (Vernunft) wishes to understand its meaning. Cognition, whose highest criterion is truth, derives that criterion from the world of appearances in which we take our bearings through sense perceptions, whose testimony is self-evident, that is, unshakeable by argument and replaceable only by other evidence. As the German translation of the Latin perceptio, the word Wahrnehmung used by Kant (what is given me in perceptions and ought to be true [Wahr]) clearly indicates, truth is located in the evidence of the senses. But that is by no means the case with meaning and with the faculty of thought, which searches for it; the latter does not ask what something is or whether it exists at all—its existence is always taken for granted-but what it means for it to be. This distinction between truth and meaning seems to me to be not only decisive for any inquiry i
nto the nature of human thinking but also to be the necessary consequence of Kant's crucial distinction between reason and intellect. Admittedly, Kant himself never pursued that particular implication of his own thought; in fact, a clear-cut line of demarcation between these two altogether different modes cannot be found in the history of philosophy. The exceptions—occasional remarks by Aristotíe in On Interpretation— remained without significance for Aristotle's later philosophy. In that early treatise on language he writes: Every "logos [sentence, in the context] is a significant sound (phōnē sēmantikē)"; it gives a sign, points out something. But "not every logos is revealing (apophantikos), only those in which true speech or false speech (alētheuein or pseudesthai) holds sway. This is not always the case; for example, a prayer is a logos [it is significant] but neither true nor false."74
The questions raised by our thirst for knowledge arise from our curiosity about the world, our desire to investigate whatever is given to our sensory apparatus. The famous first sentence of Aristotle's Metaphysics, "Pontes anthrōpoi tou eidenai oregontai physei"75 —"All men by nature desire to know"—literally translated reads: "All men desire to see and to have seen [that is, to know]," and Aristotle immediately adds: "An indication of this is our love of the senses; for they are loved for their own sake, quite apart from their use." The questions raised by the desire to know are in principle all answerable by common-sense experience and common-sense reasoning; they are exposed to corrigible error and illusion in the same way as sense perceptions and experiences. Even the relendessness of modern science's Progress, which constantly corrects itself by discarding the answers and reformulating the questions, does not contradict science's basic goal—to see and to know the world as it is given to the senses—and its concept of truth is derived from the common-sense experience of irrefutable evidence, which dispels error and illusion. But the questions raised by thinking and which it is in reason's very nature to raise—questions of meaning—are all unanswerable by common sense and the refinement of it we call science. The quest for meaning is "meaningless" to common sense and common-sense reasoning because it is the sixth sense's function to fit us into the world of appearances and make us at home in the world given by our five senses; there we are and no questions asked.
What science and the quest for knowledge are after is irrefutable truth, that is, propositions human beings are not free to reject—they are compelling. They are of two kinds, as we have known since Leibniz: truths of reasoning and truths of fact. The main distinction between them lies in the degree of their force of compulsion: the truths of "Reasoning are necessary and their opposite is impossible" while "those of Fact are contingent and their opposite is possible."76 The distinction is very important although perhaps not in the sense Leibniz himself meant. Truths of fact, their contingency notwithstanding, are as compelling for anybody witnessing them with his own eyes as the proposition that two and two make four is for anybody in his right mind. The point is only that a fact, an event, can never be witnessed by everyone who may want to know about it, whereas rational or mathematical truth presents itself as self-evident to everyone endowed with the same brain power; its compelling nature is universal, while the compelling force of factual truth is limited; it does not reach those who, not having been witnesses, have to rely on the testimony of others, whom one may or may not believe. The true opposite of factual, as distinguished from rational, truth is not error or illusion but the deliberate lie.
Leibniz' distinction between the truths of fact and the truths of reasoning, whose highest form is mathematical reasoning—which deals only with thought-things and needs neither witnesses nor the sensorily given—is based on the age-old distinction between necessity and contingency, according to which all that is necessary, and whose opposite is impossible, possesses a higher ontological dignity than whatever is but could also not be. This conviction that mathematical reasoning should serve as a paradigm for all thought is probably as old as Pythagoras; at any rate we find it in Plato's refusal to admit anyone to philosophy who has not been trained in mathematics. It is still at the root of the medieval dictamen rationis, the dictate of reason. That truth compels with the force of necessity ( anagkē ), which is far stronger than the force of violence (bia), is an old topos in Greek philosophy, and it is always meant as a compliment to truth that it can compel men with the irresistible force of Necessity (hyp' autēs alētheias anagkasthentes, in the words of Aristotle77 ). "Euclide," as Mercier de la Rivière once noted, "est un véritable despote; et les vérités qu'il nous a transmises, sont des lois véritablement despo-tiques."78 The same notion led Grotius to the conviction that "even God cannot cause two times two not to make four"—a very questionable proposition not only because it would put God under the dictate of necessity but because, if true, it would be equally valid for the evidence of sense perception, and it was on these grounds that Duns Scotus had questioned it.
The source of mathematical truth is the human brain, and brain power is no less natural, no less equipped to guide us through an appearing world, than our senses plus common sense and the extension of it that Kant called intellect. The best proof of this may lie in the otherwise quite mysterious fact that mathematical reasoning, the purest activity of our brain, and at first glance, because of its abstraction from all qualities given to our senses, the farthest removed from sheer common-sense reasoning, could play such an enormously liberating role in science's exploration of the universe. The intellect, the organ of knowledge and cognition, is still of this world; in the words of Duns Scotus, it falls under the sway of nature, cadit sub natura, and carries with it all the necessities to which a living being, endowed with sense organs and brain power, is subject. The opposite of necessity is not contingency or accident but freedom. Everything that appears to human eyes, everything that occurs to the human mind, everything that happens to mortals for better or worse is "contingent," including their own existence. We all know:
Unpredictably, decades ago, You arrived
among that unending cascade of creatures spewed
from Nature's maw. A random event, says Science.
But that does not prevent us from answering with the poet:
Random my bottom! A true miracle, say I,
for who is not certain that he was meant to be?79
But this being "meant to be" is not a truth; it is a highly meaningful proposition.
In other words, there are no truths beyond and above factual truths: all scientific truths are factual truths, those engendered by sheer brain power and expressed in a specially designed sign language not excluded, and only factual statements are scientifically verifiable. Thus the statement "A triangle laughs" is not untrue but meaningless, whereas the old ontological demonstration of the existence of God, as we find it in Anselm of Canterbury, is not valid and in this sense not true, but it is full of meaning. Knowing certainly aims at truth, even if this truth, as in the sciences, is never an abiding truth but a provisional verity that we expect to exchange against other, more accurate verities as knowledge progresses. To expect truth to come from thinking signifies that we mistake the need to think with the urge to know. Thinking can and must be employed in the attempt to know, but in the exercise of this function it is never itself; it is but the handmaiden of an altogether different enterprise. (Hegel seems to have been the first to protest against the modern development that tends to put philosophy in a position similar to the one it had in the Middle Ages. "Then, philosophy was supposed to be the handmaiden of theology, humbly accepting its achievements, and asked to bring them into a clean logical order and present them in a plausible, conceptually demonstrable context. Now, philosophy is supposed to be the handmaiden of the other sciences....Its task is to demonstrate the methods of the sciences"—something Hegel denounces as "catching the shadow of shadows."80 )
Truth is what we are compelled to admit by the nature either of our senses or of our brain. The proposition that everybody who is "was meant to be" can easily be refuted; but the c
ertainty of the I "was meant to be" will survive refutation intact because it is inherent in every thinking reflection on the I-am.
By drawing a distinguishing line between truth and meaning, between knowing and thinking, and by insisting on its importance, I do not wish to deny that thinking's quest for meaning and knowledge's quest for truth are connected. By posing the unanswerable questions of meaning, men establish themselves as question-asking beings. Behind all the cognitive questions for which men find answers, there lurk the unanswerable ones that seem entirely idle and have always been denounced as such. It is more than likely that men, if they were ever to lose the appetite for meaning we call thinking and cease to ask unanswerable questions, would lose not only the ability to produce those thought-things that we call works of art but also the capacity to ask all the answerable questions upon which every civilization is founded. In this sense, reason is the a priori condition of the intellect and of cognition; it is because reason and intellect are so connected, despite utter difference in mood and purpose, that the philosophers have always been tempted to accept the criterion of truth—so valid for science and everyday life—as applicable to their own rather extraordinary business as well. For our desire to know, whether arising out of practical or purely theoretical perplexities, can be fulfilled when it reaches its prescribed goal, and while our thirst for knowledge may be unquenchable because of the immensity of the unknown, the activity itself leaves behind a growing treasure of knowledge that is retained and kept in store by every civilization as part and parcel of its world. The loss of this accumulation and of the technical expertise required to conserve and increase it inevitably spells the end of this particular world. The thinking activity on the contrary leaves nothing so tangible behind, and the need to think can therefore never be stilled by the insights of "wise men." As far as positive results are concerned, the most we can expect from it is what Kant finally achieved in carrying out his purpose "to extend, albeit only negatively, our use of reason beyond the limitations of the sensorily given world, that is, to eliminate the obstacles by which reason hinders itself."81