Section 40
Original German
§ 40.
Reine Mathematik und reine Naturwissenschaft hätten zum Behuf ihrer eigenen Sicherheit und Gewißheit keiner dergleichen Deduction bedurft, als wir bisher von beiden zu Stande gebracht haben; denn die erstere stützt sich auf ihre eigene Evidenz, die zweite aber, obgleich aus reinen Quellen des Verstandes entsprungen, dennoch auf Erfahrung und deren durchgängige Bestätigung; welcher letztern Zeugniß sie darum nicht gänzlich ausschlagen und entbehren kann, weil sie mit aller ihrer Gewißheit dennoch, als Philosophie, es der Mathematik niemals gleich thun kann. Beide Wissenschaften hatten also die gedachte Untersuchung nicht für sich, sondern für eine andere Wissenschaft, nämlich Metaphysik, nöthig.
Metaphysik hat es außer mit Naturbegriffen, die in der Erfahrung jederzeit ihre Anwendung finden, noch mit reinen Vernunftbegriffen zu thun, die niemals in irgend einer nur immer möglichen Erfahrung gegeben werden, mithin mit Begriffen, deren objective Realität (daß sie nicht bloße Hirngespinste sind), und mit Behauptungen, deren Wahrheit oder Falschheit durch keine Erfahrung bestätigt oder aufgedeckt werden kann; und dieser Theil der Metaphysik ist überdem gerade derjenige, welcher den wesentlichen Zweck derselben, wozu alles andre nur Mittel ist, ausmacht, und so bedarf diese Wissenschaft einer solchen Deduction um ihrer selbst willen. Die uns jetzt vorgelegte dritte Frage betrifft also gleichsam den Kern und das Eigenthümliche der Metaphysik, nämlich die Beschäftigung der Vernunft blos mit sich selbst und, indem sie über ihre eigene Begriffe brütet, die unmittelbar daraus vermeintlich entspringende Bekanntschaft mit Objecten, ohne dazu der Vermittelung der Erfahrung nöthig zu haben, noch überhaupt durch dieselbe dazu gelangen zu können327.1.
Ohne Auflösung dieser Frage thut sich Vernunft niemals selbst gnug. Der Erfahrungsgebrauch, auf welchen die Vernunft den reinen Verstand einschränkt, erfüllt nicht ihre eigene ganze Bestimmung. Jede einzelne Erfahrung ist nur ein Theil von der ganzen Sphäre ihres Gebietes, das absolute Ganze aller möglichen Erfahrung ist aber selbst keine Erfahrung und dennoch ein nothwendiges Problem für die Vernunft, zu dessen bloßer Vorstellung sie ganz anderer Begriffe nöthig hat, als jener reinen Verstandesbegriffe, deren Gebrauch nur immanent ist, d. i. auf Erfahrung geht, so weit sie gegeben werden kann, indessen daß Vernunftbegriffe auf die Vollständigkeit, d. i. die collective Einheit der ganzen möglichen Erfahrung, und dadurch über jede gegebne Erfahrung hinausgehen und transscendent werden.
So wie also der Verstand der Kategorien zur Erfahrung bedurfte, so enthält die Vernunft in sich den Grund zu Ideen, worunter ich nothwendige Begriffe verstehe, deren Gegenstand gleichwohl in keiner Erfahrung gegeben werden kann. Die letztern sind eben sowohl in der Natur der Vernunft, als die erstere in der Natur des Verstandes gelegen, und wenn jene einen Schein bei sich führen, der leicht verleiten kann, so ist dieser Schein unvermeidlich, obzwar, „daß er nicht verführe,“ gar wohl verhütet werden kann.
Da aller Schein darin besteht, daß der subjective Grund des Urtheils für objectiv gehalten wird, so wird ein Selbsterkenntniß der reinen Vernunft in ihrem transscendenten (überschwenglichen) Gebrauch das einzige Verwahrungsmittel gegen die Verirrungen sein, in welche die Vernunft geräth, wenn sie ihre Bestimmung mißdeutet und dasjenige transscendenter Weise aufs Object an sich selbst bezieht, was nur ihr eigenes Subject und die Leitung desselben in allem immanenten Gebrauche angeht.
327.1. Wenn man sagen kann, daß eine Wissenschaft wenigstens in der Idee aller Menschen wirklich sei, so bald es ausgemacht ist, daß die Aufgaben, die darauf führen, durch die Natur der menschlichen Vernunft jedermann vorgelegt und daher auch jederzeit darüber viele, obgleich fehlerhafte Versuche unvermeidlich sind, so wird man auch sagen müssen: Metaphysik sei subjective (und zwar nothwendiger Weise) wirklich, und da fragen wir also mit Recht, wie sie (objective) möglich sei.
Musean translation
Mouseia’s complete machine-assisted Musean translation, made directly from the complete German of the Prolegomena (AA IV 253–383, all §§1–60 and the Appendix), for fidelity, the steps of Kant’s argument, clarity and structure.
§ 40.
For their own security and certainty, pure mathematics and pure natural science would have needed no such deduction as we have so far accomplished for both. The former rests on its own self-evidence; the latter, although it springs from pure sources of the understanding, nevertheless rests on experience and its thoroughgoing confirmation. It cannot entirely reject or dispense with the testimony of experience, because, for all its certainty, it can never, as philosophy, equal mathematics. Neither science, then, needed the investigation in question for itself, but for another science, namely metaphysics.
Besides concepts of nature, which always find their application in experience, metaphysics also deals with pure concepts of reason, which are never given in any experience whatever that could possibly occur. It therefore deals with concepts whose objective reality—that they are not mere fantasies—cannot be established by experience, and with assertions whose truth or falsity cannot be confirmed or exposed by any experience. Moreover, this part of metaphysics is precisely what constitutes its essential purpose, to which everything else is only a means; and so this science needs such a deduction for its own sake. The third question now before us thus concerns, as it were, the very heart and distinctive character of metaphysics: reason's occupation solely with itself and, as it broods over its own concepts, the acquaintance with objects that supposedly arises directly from them, without needing experience to mediate it or indeed being able to reach it through experience.327.1
Without a solution to this question, reason can never satisfy itself. The use within experience to which reason confines the pure understanding does not fulfill reason's own entire vocation. Each individual experience is only a part of the whole sphere of its domain; but the absolute whole of all possible experience is not itself an experience, and is nevertheless a necessary problem for reason. Merely to represent it, reason needs concepts quite different from those pure concepts of the understanding whose use is only immanent—that is, directed toward experience as far as it can be given. Concepts of reason, by contrast, aim at completeness, that is, the collective unity of the whole of possible experience, and thereby go beyond every given experience and become transcendent.
Just as the understanding needed the categories for experience, so reason contains within itself the ground of ideas, by which I mean necessary concepts whose object nevertheless cannot be given in any experience. These lie in the nature of reason just as the former lie in the nature of the understanding; and if they carry with them an illusion that can easily mislead, this illusion is unavoidable, although it is quite possible to prevent it "from deceiving us."
Since all illusion consists in taking the subjective ground of a judgment to be objective, pure reason's self-knowledge in its transcendent (extravagant) use will be the sole safeguard against the errors into which reason falls when it misconstrues its vocation and refers, in a transcendent way, to the object in itself what concerns only its own subject and the guidance of that subject in every immanent use.
327.1. If we can say that a science actually exists at least in everyone's idea as soon as it is established that the problems leading to it are posed to everyone by the nature of human reason, and that many attempts at them, though mistaken, are therefore always unavoidable, then we must also say that metaphysics is subjectively (and indeed necessarily) actual; and so we rightly ask how it is (objectively) possible.
Plain English translation
Mouseia’s complete Plain English edition, made independently and directly from the same complete German text.
§ 40.
Pure mathematics and pure natural science would not have needed the kind of justification we have so far provided for them for their own security and certainty. Mathematics rests on its own self-evidence. Natural science, though it comes from pure sources in the understanding, also rests on experience and its consistent confirmation. It cannot entirely reject or do without the testimony of experience. Despite all its certainty, as philosophy it can never match mathematics. These two sciences therefore needed this investigation not for themselves, but for another science: metaphysics.
Besides concepts of nature, which always find their application in experience, metaphysics deals with pure concepts of reason. These can never be given in any possible experience whatsoever. It thus deals with concepts whose objective reality—that they are not mere fantasies—cannot be confirmed by experience, and with claims whose truth or falsity no experience can establish or expose. Moreover, this part of metaphysics is precisely its essential purpose. Everything else is only a means to that purpose. So this science needs such a justification for its own sake. The third question now before us concerns what is, so to speak, the core and distinctive feature of metaphysics. Reason occupies itself solely with itself. By brooding over its own concepts, it supposedly gains direct acquaintance with objects, without needing experience as an intermediary, or even being able to reach them through experience at all.327.1
Until this question is answered, reason can never satisfy itself. The use in experience to which reason restricts the pure understanding does not fulfill reason's entire purpose. Each particular experience is only a part of the whole range of its domain. But the absolute whole of all possible experience is not itself an experience. It is nevertheless a necessary problem for reason. Even to represent this whole, reason needs concepts quite different from those pure concepts of the understanding whose use is only immanent—that is, directed to experience insofar as it can be given. Concepts of reason, by contrast, aim at completeness: the collective unity of all possible experience. They thereby go beyond every given experience and become transcendent.
Just as the understanding needed the categories for experience, reason contains the basis for ideas. By these I mean necessary concepts whose object nevertheless cannot be given in any experience. These ideas belong to the nature of reason just as much as the categories belong to the nature of the understanding. If ideas bring with them an illusion that can easily mislead us, this illusion is unavoidable. But we can certainly prevent it “from deceiving us.”
Every illusion consists in taking a subjective ground of judgment to be objective. So the only safeguard against reason's errors will be its knowledge of itself in its transcendent use, which goes beyond experience. Reason falls into these errors when it misunderstands its purpose. It then applies to the object in itself, in a transcendent way, something that concerns only its own subject and the guidance of that subject in every immanent use.
327.1. We may say that a science actually exists, at least in everyone's idea of it, once the following is established: the nature of human reason presents everyone with the problems that lead to it, and so makes many attempts at it unavoidable at all times, even if those attempts are mistaken. If so, we must also say that metaphysics actually exists subjectively, and necessarily so. We are therefore right to ask how it is possible objectively.
About this section
Section 40 is part of Prolegomena to Any Future Metaphysics by Immanuel Kant. This page sets the German original beside 2 direct-source translations, so any line can be checked against the source. It is section 48 of 72 in the work, which is kept in the European tradition.
Open the work page for the full contents, every edition, and the download links, or go back to Explore to browse other complete works in the European tradition. The reader keeps your place when you are signed in and lets you compare the original with each translation, one edition at a time.