Preface
Original German
Vorrede. A 3 V:3
Warum diese Kritik nicht eine Kritik der reinen praktischen, sondern schlechthin der praktischen Vernunft überhaupt betitelt wird, obgleich der Parallelism derselben mit der speculativen das erstere zu erfordern scheint, darüber giebt diese Abhandlung hinreichenden Aufschluß. Sie soll blos darthun, daß es reine praktische Vernunft gebe, und kritisirt in dieser Absicht ihr ganzes praktisches Vermögen. Wenn es ihr hiemit gelingt, so bedarf sie das reine Vermögen selbst nicht zu kritisiren, um zu sehen, ob sich die Vernunft mit einem solchen als einer bloßen Anmaßung nicht übersteige (wie es wohl mit der speculativen geschieht). Denn wenn sie als reine Vernunft wirklich praktisch ist, so beweiset sie ihre und ihrer Begriffe Realität durch die That, und alles Vernünfteln wider die Möglichkeit, es zu sein, ist vergeblich.
Mit diesem Vermögen steht auch die transscendentale Freiheit nunmehr A 4 fest, und zwar in derjenigen absoluten Bedeutung genommen, worin die speculative Vernunft beim Gebrauche des Begriffs der Causalität sie bedurfte, um sich wider die Antinomie zu retten, darin sie unvermeidlich geräth, wenn sie in der Reihe der Causalverbindung sich das Unbedingte denken will, welchen Begriff sie aber nur problematisch, als nicht unmöglich zu denken, aufstellen konnte, ohne ihm seine objective Realität zu sichern, sondern allein um nicht durch vorgebliche Unmöglichkeit dessen, was sie doch wenigstens als denkbar gelten lassen muß, in ihrem Wesen angefochten und in einen Abgrund des Scepticisms gestürzt zu werden.
Der Begriff der Freiheit, so fern dessen Realität durch ein apodiktisches Gesetz der praktischen Vernunft bewiesen ist, macht nun den Schlußstein von dem ganzen Gebäude eines Systems der reinen, selbst der speculativen V:4 Vernunft aus, und alle andere Begriffe (die von Gott und Unsterblichkeit), welche als bloße Ideen in dieser ohne Haltung bleiben, schließen sich nun an ihn an und bekommen mit ihm und durch ihn Bestand und objective Realität, d. i. die Möglichkeit derselben wird dadurch A 5 bewiesen, daß Freiheit wirklich ist; denn diese Idee offenbart sich durchs moralische Gesetz.
Freiheit ist aber auch die einzige unter allen Ideen der speculativen Vernunft, wovon wir die Möglichkeit a priori wissen, ohne sie doch einzusehen, weil sie die Bedingung1 des moralischen Gesetzes ist, welches wir wissen. Die Ideen von Gott und Unsterblichkeit sind aber nicht Bedingungen des moralischen Gesetzes, sondern nur Bedingungen des nothwendigen Objects eines durch dieses Gesetz bestimmten Willens, d. i. des A 6 bloß praktischen Gebrauchs unserer reinen Vernunft; also können wir von jenen Ideen auch, ich will nicht bloß sagen, nicht die Wirklichkeit, sondern auch nicht einmal die Möglichkeit zu erkennen und einzusehen behaupten. Gleichwohl aber sind die Bedingungen der Anwendung des moralisch bestimmten Willens auf sein ihm a priori gegebenes Object (das höchste Gut). Folglich kann und muß ihre Möglichkeit in dieser praktischen Beziehung angenommen werden, ohne sie doch theoretisch zu erkennen und einzusehen. Für die letztere Forderung ist in praktischer Absicht genug, daß sie keine innere Unmöglichkeit (Widerspruch) enthalten. Hier ist nun ein in Vergleichung mit der speculativen Vernunft bloß subjectiver Grund des Fürwahrhaltens, der doch einer eben so reinen, aber praktischen Vernunft objectiv gültig ist, dadurch den Ideen von Gott und Unsterblichkeit vermittelst des Begriffs der Freiheit objective Realität und Befugniß, ja subjective Nothwendigkeit (Bedürfniß der reinen Vernunft) sie anzunehmen verschafft wird, ohne daß dadurch doch die Vernunft V:5 im theoretischen Erkenntnisse erweitert, sondern nur die Möglichkeit, die vorher nur Problem war, hier Assertion wird, gegeben und so der praktische A 7 Gebrauch der Vernunft mit den Elementen des theoretischen verknüpft wird. Und dieses Bedürfniß ist nicht etwa ein hypothetisches einer beliebigen Absicht der Speculation, daß man etwas annehmen müsse, wenn man zur Vollendung des Vernunftgebrauchs in der Speculation hinaufsteigen will, sondern ein gesetzliches, etwas anzunehmen, ohne welches nicht geschehen kann, was man sich zur Absicht seines Thuns und Lassens unnachlaßlich setzen soll.
Es wäre allerdings befriedigender für unsere speculative Vernunft, ohne diesen Umschweif jene Aufgaben für sich aufzulösen und sie als Einsicht zum praktischen Gebrauche aufzubewahren; allein es ist einmal mit unserem Vermögen der Speculation nicht so gut bestellt. Diejenige, welche sich solcher hohen Erkenntnisse rühmen, sollten damit nicht zurückhalten, sondern sie öffentlich zur Prüfung und Hochschätzung darstellen. Sie wollen beweisen; wohlan! so mögen sie denn beweisen, und die Kritik legt ihnen als Siegern ihre ganze Rüstung zu Füßen. Quid statis? Nolint. Atqui licet esse beatis. — Da sie also in der That nicht wollen, vermuthlich weil sie nicht können, so müssen wir jene doch nur wiederum zur Hand A 8 nehmen, um die Begriffe von Gott, Freiheit und Unsterblichkeit, für welche die Speculation nicht hinreichende Gewährleistung ihrer Möglichkeit findet, in moralischem Gebrauche der Vernunft zu suchen und auf demselben zu gründen.
Hier erklärt sich auch allererst das Räthsel der Kritik, wie man dem übersinnlichen Gebrauche der Kategorien in der Speculation objective Realität absprechen und ihnen doch in Ansehung der Objecte der reinen praktischen Vernunft diese Realität zugestehen könne; denn vorher muß dieses nothwendig inconsequent aussehen, so lange man einen solchen praktischen Gebrauch nur dem Namen nach kennt. Wird man aber jetzt durch eine vollständige Zergliederung des letzteren inne, daß gedachte Realität hier gar auf keine theoretische Bestimmung der Kategorien und Erweiterung des Erkenntnisses zum Übersinnlichen hinausgehe, sondern nur hiedurch gemeint sei, daß ihnen in dieser Beziehung überall ein Object zukomme, weil sie entweder in der nothwendigen Willensbestimmung a priori enthalten, oder mit dem Gegenstande derselben unzertrennlich verbunden sind, so verschwindet jene Inconsequenz, weil man A 9 einen anderen Gebrauch von jenen Begriffen macht, als speculative Vernunft V:6 bedarf. Dagegen eröffnet sich nun eine vorher kaum zu erwartende und sehr befriedigende Bestätigung der consequenten Denkungsart der speculativen Kritik darin, daß, da diese die Gegenstände der Erfahrung als solche und darunter selbst unser eigenes Subject nur für Erscheinungen gelten zu lassen, ihnen aber gleichwohl Dinge an sich selbst zum Grunde zu legen, also nicht alles Übersinnliche für Erdichtung und dessen Begriff für leer an Inhalt zu halten einschärfte: praktische Vernunft jetzt für sich selbst, und ohne mit der speculativen Verabredung getroffen zu haben, einem übersinnlichen Gegenstande der Kategorie der Causalität, nämlich der Freiheit, Realität verschafft (obgleich als praktischem Begriffe auch nur zum praktischen Gebrauche), also dasjenige, was dort bloß gedacht werden konnte, durch ein Factum bestätigt. Hiebei erhält nun zugleich die befremdliche, obzwar unstreitige, Behauptung der speculativen Kritik, daß sogar das denkende Subject ihm selbst in der inneren Anschauung bloß Erscheinung sei, in der Kritik der praktischen Vernunft auch ihre volle Bestätigung, so gut, daß man auf sie kommen muß, A 10 wenn die erstere diesen Satz auch gar nicht bewiesen hätte2.
Hiedurch verstehe ich auch, warum die erheblichsten Einwürfe wider die Kritik, die mir bisher noch vorgekommen sind, sich gerade um diese zwei Angel drehen: nämlich einerseits im theoretischen Erkenntniß geleugnete und im praktischen behauptete objective Realität der auf Noumenen angewandten Kategorien, andererseits die paradoxe Forderung, sich als Subject der Freiheit zum Noumen, zugleich aber auch in Absicht auf die Natur zum Phänomen in seinem eigenen empirischen Bewußtsein zu machen. Denn so lange man sich noch keine bestimmte Begriffe von Sittlichkeit und Freiheit machte, konnte man nicht errathen, was man A 11 einerseits der vorgeblichen Erscheinung als Noumen zum Grunde legen wolle, und andererseits, ob es überall auch möglich sei, sich noch von ihm einen Begriff zu machen, wenn man vorher alle Begriffe des reinen Verstandes im theoretischen Gebrauche schon ausschließungsweise den bloßen Erscheinungen gewidmet hätte. Nur eine ausführliche Kritik der praktischen V:7 Vernunft kann alle diese Mißdeutung heben und die consequente Denkungsart, welche eben ihren größten Vorzug ausmacht, in ein helles Licht setzen.
So viel zur Rechtfertigung, warum in diesem Werke die Begriffe und Grundsätze der reinen speculativen Vernunft, welche doch ihre besondere Kritik schon erlitten haben, hier hin und wieder nochmals der Prüfung unterworfen werden, welches dem systematischen Gange einer zu errichtenden Wissenschaft sonst nicht wohl geziemt (da abgeurtheilte Sachen billig nur angeführt und nicht wiederum in Anregung gebracht werden müssen), doch hier erlaubt, ja nöthig war: weil die Vernunft mit jenen Begriffen im Übergange zu einem ganz anderen Gebrauche betrachtet wird, als den sie dort von ihnen machte. Ein solcher Übergang macht aber eine Vergleichung A 12 des älteren mit dem neuern Gebrauche nothwendig, um das neue Gleis von dem vorigen wohl zu unterscheiden und zugleich den Zusammenhang derselben bemerken zu lassen. Man wird also Betrachtungen dieser Art, unter andern diejenige, welche nochmals auf den Begriff der Freiheit, aber im praktischen Gebrauche der reinen Vernunft, gerichtet worden, nicht wie Einschiebsel betrachten, die etwa nur dazu dienen sollen, um Lücken des kritischen Systems der speculativen Vernunft auszufüllen (denn dieses ist in seiner Absicht vollständig) und, wie es bei einem übereilten Baue herzugehen pflegt, hintennach noch Stützen und Strebepfeiler anzubringen, sondern als wahre Glieder, die den Zusammenhang des Systems bemerklich machen, um Begriffe, die dort nur problematisch vorgestellt werden konnten, jetzt in ihrer realen Darstellung einsehen zu lassen. Diese Erinnerung geht vornehmlich den Begriff der Freiheit an, von dem man mit Befremdung bemerken muß, daß noch so viele ihn ganz wohl einzusehen und die Möglichkeit derselben erklären zu können sich rühmen, indem sie ihn bloß in psychologischer Beziehung betrachten, indessen daß, wenn sie ihn vorher in transscendentaler genau erwogen hätten, sie sowohl A 13 seine Unentbehrlichkeit als problematischen Begriffs in vollständigem Gebrauche der speculativen Vernunft, als auch die völlige Unbegreiflichkeit desselben hätten erkennen und, wenn sie nachher mit ihm zum praktischen Gebrauche gingen, gerade auf die nämliche Bestimmung des letzteren in Ansehung seiner Grundsätze von selbst hätten kommen müssen, zu welcher sie sich sonst so ungern verstehen wollen. Der Begriff der Freiheit ist der Stein des Anstoßes für alle Empiristen, aber auch der Schlüssel zu den erhabensten praktischen Grundsätzen für kritische Moralisten, die dadurch V:8 einsehen, daß sie nothwendig rational verfahren müssen. Um deswillen ersuche ich den Leser, das, was zum Schlusse der Analytik über diesen Begriff gesagt wird, nicht mit flüchtigem Auge zu übersehen.
Ob ein solches System, als hier von der reinen praktischen Vernunft aus der Kritik der letzeren entwickelt wird, viel oder wenig Mühe gemacht habe, um vornehmlich den rechten Gesichtspunkt, aus dem das Ganze derselben richtig vorgezeichnet werden kann, nicht zu verfehlen, muß ich den Kennern einer dergleichen Arbeit zu beurtheilen überlassen. Es setzt zwar A 14 die Grundlegung zur Metaphysik der Sitten voraus, aber nur in so fern, als diese mit dem Princip der Pflicht vorläufige Bekanntschaft macht und eine bestimmte Formel derselben angiebt und rechtfertigt3; sonst besteht es durch sich selbst. Daß die Eintheilung aller praktischen Wissenschaften zur Vollständigkeit nicht mit beigefügt worden, wie es die Kritik der speculativen Vernunft leistete, dazu ist auch gültiger Grund in der Beschaffenheit dieses praktischen Vernunftvermögens anzutreffen. Denn die besondere Bestimmung der Pflichten als Menschenpflichten, um sie einzutheilen, ist nur möglich, wenn vorher das Subject dieser Bestimmung A 15 (der Mensch) nach der Beschaffenheit, mit der er wirklich ist, obzwar nur so viel als in Beziehung auf Pflicht überhaupt nöthig ist, erkannt worden; diese aber gehört nicht in eine Kritik der praktischen Vernunft überhaupt, die nur die Principien ihrer Möglichkeit, ihres Umfanges und Grenzen vollständig ohne besondere Beziehung auf die menschliche Natur angeben soll. Die Eintheilung gehört also hier zum System der Wissenschaft, nicht zum System der Kritik.
Ich habe einem gewissen wahrheitliebenden und scharfen, dabei also doch immer achtungswürdigen Recensenten jener Grundlegung zur Metaphysik der Sitten auf seinen Einwurf, daß der Begriff des V:9 Guten dort nicht (wie es seiner Meinung nach nöthig gewesen wäre) vor dem moralischen Princip festgesetzt worden4, in dem zweiten Hauptstücke der Analytik, wie ich hoffe, Genüge gethan; eben so auch auf A 16 manche andere Einwürfe Rücksicht genommen, die mir von Männern zu A 17 Händen gekommen sind, die den Willen blicken lassen, daß die Wahrheit auszumitteln ihnen am Herzen liegt (denn die, so nur ihr altes System A 18 vor Augen haben, und bei denen schon vorher beschlossen ist, was gebilligt oder mißbilligt werden soll, verlangen doch keine Erörterung, die ihrer V:10 Privatabsicht im Wege sein könnte); und so werde ich es auch fernerhin halten.
Wenn es um die Bestimmung eines besonderen Vermögens der menschlichen Seele nach seinen Quellen, Inhalte und Grenzen zu thun ist, so kann man zwar nach der Natur des menschlichen Erkenntnisses nicht anders als von den Theilen derselben, ihrer genauen und (so viel als nach der jetzigen Lage unserer schon erworbenen Elemente derselben möglich ist) vollständigen Darstellung anfangen. Aber es ist noch eine zweite Aufmerksamkeit, die mehr philosophisch und architektonisch ist: nämlich die Idee des Ganzen richtig zu fassen und aus derselben alle jene Theile in ihrer wechselseitigen Beziehung auf einander vermittelst der Ableitung derselben von dem Begriffe jenes Ganzen in einem reinen Vernunftvermögen ins Auge zu fassen. Diese Prüfung und Gewährleistung ist nur A 19 durch die innigste Bekanntschaft mit dem System möglich, und die, welche in Ansehung der ersteren Nachforschung verdrossen gewesen, also diese Bekanntschaft zu erwerben nicht der Mühe werth geachtet haben, gelangen nicht zur zweiten Stufe, nämlich der Übersicht, welche eine synthetische Wiederkehr zu demjenigen ist, was vorher analytisch gegeben worden, und es ist kein Wunder, wenn sie allerwärts Inconsequenzen finden, obgleich die Lücken, die diese vermuthen lassen, nicht im System selbst, sondern blos in ihrem eigenen unzusammenhängenden Gedankengange anzutreffen sind.
Ich besorge in Ansehung dieser Abhandlung nichts von dem Vorwurfe, eine neue Sprache einführen zu wollen, weil die Erkenntnißart sich hier von selbst der Popularität nähert. Dieser Vorwurf konnte auch niemanden in Ansehung der ersteren Kritik beifallen, der sie nicht blos durchgeblättert, sondern durchgedacht hatte. Neue Worte zu künsteln, wo die Sprache schon so an Ausdrücken für gegebene Begriffe keinen Mangel A 20 hat, ist eine kindische Bemühung, sich unter der Menge, wenn nicht durch neue und wahre Gedanken, doch durch einen neuen Lappen auf dem alten Kleide auszuzeichnen. Wenn daher die Leser jener Schrift populärere Ausdrücke wissen, die doch dem Gedanken eben so angemessen sind, als mir jene zu sein scheinen, oder etwa die Nichtigkeit dieser Gedanken selbst, mithin zugleich jedes Ausdrucks, der ihn bezeichnet, darzuthun sich getrauen: so würden sie mich durch das erstere sehr verbinden, denn ich will nur verstanden sein, in Ansehung des zweiten aber sich ein Verdienst um die Philosophie erwerben. So lange aber jene Gedanken noch stehen, V:11 zweifele ich sehr, daß ihnen angemessene und doch gangbarere Ausdrücke dazu aufgefunden werden dürften.5
V:12 Auf diese Weise wären denn nunmehr die Principien a priori zweier A 21 Vermögen des Gemüths, des Erkenntniß- und Begehrungsvermögens, ausgemittelt A 22 und nach den Bedingungen, dem Umfange und Grenzen ihres A 23 Gebrauchs bestimmt, hiedurch aber zu einer systematischen, theoretischen sowohl als praktischen Philosophie als Wissenschaft sicherer Grund gelegt.
Was Schlimmeres könnte aber diesen Bemühungen wohl nicht begegnen, als wenn jemand die unerwartete Entdeckung machte, daß es überall gar kein Erkenntniß a priori gebe, noch geben könne. Allein es hat hiemit keine Noth. Es wäre eben so viel, als ob jemand durch Vernunft beweisen wollte, daß es keine Vernunft gebe. Denn wir sagen nur, daß wir etwas durch Vernunft erkennen, wenn wir uns bewußt sind, daß wir es auch hätten wissen können, wenn es uns auch nicht so in der Erfahrung vorgekommen wäre; mithin ist Vernunfterkenntniß und Erkenntniß a priori A 24 einerlei. Aus einem Erfahrungssatze Nothwendigkeit (ex pumice aquam) auspressen wollen, mit dieser auch wahre Allgemeinheit (ohne welche kein Vernunftschluß, mithin auch nicht der Schluß aus der Analogie, welche eine wenigstens präsumirte Allgemeinheit und objective Nothwendigkeit ist und diese also doch immer voraussetzt) einem Urtheile verschaffen wollen, ist gerader Widerspruch. Subjective Nothwendigkeit, d. i. Gewohnheit, statt der objectiven, die nur in Urtheilen a priori stattfindet, unterschieben, heißt der Vernunft das Vermögen absprechen, über den Gegenstand zu urtheilen, d. i. ihn, und was ihm zukomme, zu erkennen, und z. B. von dem, was öfters und immer auf einen gewissen vorhergehenden Zustand folgte, nicht sagen, daß man aus diesem auf jenes schließen könne (denn das würde objective Nothwendigkeit und Begriff von einer Verbindung a priori bedeuten), sondern nur ähnliche Fälle (mit den Thieren auf ähnliche Art) erwarten dürfe, d. i. den Begriff der Ursache im Grunde als falsch und bloßen Gedankenbetrug verwerfen. Diesem Mangel der objectiven A 25 und daraus folgenden allgemeinen Gültigkeit dadurch abhelfen wollen, daß man doch keinen Grund sähe, andern vernünftigen Wesen eine andere Vorstellungsart beizulegen, wenn das einen gültigen Schluß abgäbe, so würde uns unsere Unwissenheit mehr Dienste zu Erweiterung unserer Erkenntniß leisten, als alles Nachdenken. Denn blos deswegen, weil wir andere vernünftige Wesen außer dem Menschen nicht kennen, würden wir ein Recht haben, sie als so beschaffen anzunehmen, wie wir uns erkennen, d. i. wir würden sie wirklich kennen. Ich erwähne hier nicht einmal, daß nicht die Allgemeinheit des Fürwahrhaltens die objective V:13 Gültigkeit eines Urtheils (d. i. die Gültigkeit desselben als Erkenntnisses) beweise, sondern, wenn jene auch zufälliger Weise zuträfe, dieses doch noch nicht einen Beweis der Übereinstimmung mit dem Object abgeben könne; vielmehr die objective Gültigkeit allein den Grund einer nothwendigen allgemeinen Einstimmung ausmache.
Hume würde sich bei diesem System des allgemeinen Empirisms A 26 in Grundsätzen auch sehr wohl befinden; denn er verlangte, wie bekannt, nichts mehr, als daß statt aller objectiven Bedeutung der Nothwendigkeit im Begriffe der Ursache eine blos subjective, nämlich Gewohnheit, angenommen werde, um der Vernunft alles Urtheil über Gott, Freiheit und Unsterblichkeit abzusprechen; und er verstand sich gewiß sehr gut darauf, um, wenn man ihm nur die Principien zugestand, Schlüsse mit aller logischen Bündigkeit daraus zu folgern. Aber so allgemein hat selbst Hume den Empirism nicht gemacht, um auch die Mathematik darin einzuschließen. Er hielt ihre Sätze für analytisch, und wenn das seine Richtigkeit hätte, würden sie in der That auch apodiktisch sein, gleichwohl aber daraus kein Schluß auf ein Vermögen der Vernunft, auch in der Philosophie apodiktische Urtheile, nämlich solche, die synthetisch wären (wie der Satz der Causalität), zu fällen, gezogen werden können. Nähme man aber den Empirism der Principien allgemein an, so wäre auch Mathematik damit eingeflochten.
Wenn nun diese mit der Vernunft, die blos empirische Grundsätze A 27 zuläßt, in Widerstreit geräth, wie dieses in der Antinomie, da Mathematik die unendliche Theilbarkeit des Raumes unwidersprechlich beweiset, der Empirism aber sie nicht verstatten kann, unvermeidlich ist: so ist die größte mögliche Evidenz der Demonstration mit den vorgeblichen Schlüssen aus Erfahrungsprincipien in offenbarem Widerspruch, und nun muß man wie der Blinde des Cheselden fragen: was betrügt mich, das Gesicht oder Gefühl? (Denn der Empirism gründet sich auf einer gefühlten, der Rationalism aber auf einer eingesehenen Nothwendigkeit.) Und so offenbart sich der allgemeine Empirism als den ächten Scepticism, den man dem Hume fälschlich in so unbeschränkter Bedeutung beilegte6, da er wenigstens einen sicheren Probirstein der Erfahrung A 28 V:14 an der Mathematik übrig ließ, statt daß jener schlechterdings keinen Probirstein derselben (der immer nur in Principien a priori angetroffen werden kann) verstattet, obzwar diese doch nicht aus bloßen Gefühlen, sondern auch aus Urtheilen besteht.
Doch da es in diesem philosophischen und kritischen Zeitalter schwerlich mit jenem Empirism Ernst sein kann, und er vermuthlich nur zur Übung der Urtheilskraft, und um durch den Contrast die Nothwendigkeit rationaler Principien a priori in ein helleres Licht zu setzen, aufgestellt wird: so kann man es denen doch Dank wissen, die sich mit dieser sonst eben nicht belehrenden Arbeit bemühen wollen.
1 Damit man hier nicht Inconsequenzen anzutreffen wähne, wenn ich jetzt die Freiheit die Bedingung des moralischen Gesetzes nenne und in der Abhandlung nachher behaupte, daß das moralische Gesetz die Bedingung sei, unter der wir uns allererst der Freiheit bewußt werden können, so will ich nur erinnern, daß die Freiheit allerdings die ratio essendi des moralischen Gesetzes, das moralische Gesetz aber die ratio cognoscendi der Freiheit sei. Denn wäre nicht das moralische Gesetz in unserer Vernunft eher deutlich gedacht, so würden wir uns niemals berechtigt halten, so etwas, als Freiheit ist (ob diese gleich sich nicht widerspricht), anzunehmen. Wäre aber keine Freiheit, so würde das moralische Gesetz in uns gar nicht anzutreffen sein.
2 Die Vereinigung der Causalität als Freiheit mit ihr als Naturmechanism, davon die erste durchs Sittengesetz, die zweite durchs Naturgesetz, und zwar in einem und demselben Subjecte, dem Menschen, fest steht, ist unmöglich, ohne diesen in Beziehung auf das erstere als Wesen an sich selbst, auf das zweite aber als Erscheinung, jenes im reinen, dieses im empirischen Bewußtsein vorzustellen. Ohne dieses ist der Widerspruch der Vernunft mit sich selbst unvermeidlich.
3 Ein Recensent, der etwas zum Tadel dieser Schrift sagen wollte, hat es besser getroffen, als er wohl selbst gemeint haben mag, indem er sagt: daß darin kein neues Princip der Moralität, sondern nur eine neue Formel aufgestellt worden. Wer wollte aber auch einen neuen Grundsatz aller Sittlichkeit einführen und diese gleichsam zuerst erfinden? gleich als ob vor ihm die Welt in dem, was Pflicht sei, unwissend oder in durchgängigem Irrthume gewesen wäre. Wer aber weiß, was dem Mathematiker eine Formel bedeutet, die das, was zu thun sei, um eine Aufgabe zu befolgen, ganz genau bestimmt und nicht verfehlen läßt, wird eine Formel, welche dieses in Ansehung aller Pflicht überhaupt thut, nicht für etwas Unbedeutendes und Entbehrliches halten.
4 Man könnte mir noch den Einwurf machen, warum ich nicht auch den Begriff des Begehrungsvermögens, oder des Gefühls der Lust vorher erklärt habe; obgleich dieser Vorwurf unbillig sein würde, weil man diese Erklärung, als in der Psychologie gegeben, billig sollte voraussetzen können. Es könnte aber freilich die Definition daselbst so eingerichtet sein, daß das Gefühl der Lust der Bestimmung des Begehrungsvermögens zum Grunde gelegt würde (wie es auch wirklich gemeinhin so zu geschehen pflegt), dadurch aber das oberste Princip der praktischen Philosophie nothwendig empirisch ausfallen müßte, welches doch allererst auszumachen ist und in dieser Kritik gänzlich widerlegt wird. Daher will ich diese Erklärung hier so geben, wie sie sein muß, um diesen streitigen Punkt wie billig im Anfange unentschieden zu lassen. — Leben ist das Vermögen eines Wesens, nach Gesetzen des Begehrungsvermögens zu handeln. Das Begehrungsvermögen ist das Vermögen desselben, durch seine Vorstellungen Ursache von der Wirklichkeit der Gegenstände dieser Vorstellungen zu sein. Lust ist die Vorstellung der Übereinstimmung des Gegenstandes oder der Handlung mit den subjectiven Bedingungen des Lebens, d. i. mit dem Vermögen der Causalität einer Vorstellung in Ansehung der Wirklichkeit ihres Objects (oder der Bestimmung der Kräfte des Subjects zur Handlung es hervorzubringen). Mehr brauche ich nicht zum Behuf der Kritik von Begriffen, die aus der Psychologie entlehnt werden, das übrige leistet die Kritik selbst. Man wird leicht gewahr, daß die Frage, ob die Lust dem Begehrungsvermögen jederzeit zum Grunde gelegt werden müsse, oder ob sie auch unter gewissen Bedingungen nur auf die Bestimmung desselben folge, durch diese Erklärung unentschieden bleibt; denn sie ist aus lauter Merkmalen des reinen Verstandes, d. i. Kategorien, zusammengesetzt, die nichts Empirisches enthalten. Eine solche Behutsamkeit ist in der ganzen Philosophie sehr empfehlungswürdig und wird dennoch oft verabsäumt, nämlich seinen Urtheilen vor der vollständigen Zergliederung des Begriffs, die oft nur sehr spät erreicht wird, durch gewagte Definition nicht vorzugreifen. Man wird auch durch den ganzen Lauf der Kritik (der theoretischen sowohl als praktischen Vernunft) bemerken, daß sich in demselben mannigfaltige Veranlassung vorfinde, manche Mängel im alten dogmatischen Gange der Philosophie zu ergänzen und Fehler abzuändern, die nicht eher bemerkt werden, als wenn man von Begriffen einen Gebrauch der Vernunft macht, der aufs Ganze derselben geht.
5 Mehr (als jene Unverständlichkeit) besorge ich hier hin und wieder Mißdeutung in Ansehung einiger Ausdrücke, die ich mit größter Sorgfalt aussuchte, um den Begriff nicht verfehlen zu lassen, darauf sie weisen. So hat in der Tafel der Kategorien der praktischen Vernunft in dem Titel der Modalität das Erlaubte und Unerlaubte (praktisch-objectiv Mögliche und Unmögliche) mit der nächstfolgenden Kategorie der Pflicht und des Pflichtwidrigen im gemeinen Sprachgebrauche beinahe einerlei Sinn; hier aber soll das erstere dasjenige bedeuten, was mit einer blos möglichen praktischen Vorschrift in Einstimmung oder Widerstreit ist (wie etwa die Auflösung aller Probleme der Geometrie und Mechanik), das zweite, was in solcher Beziehung auf ein in der Vernunft überhaupt wirklich liegendes Gesetz steht; und dieser Unterschied der Bedeutung ist auch dem gemeinen Sprachgebrauche nicht ganz fremd, wenn gleich etwas ungewöhnlich. So ist es z. B. einem Redner als solchem unerlaubt, neue Worte oder Wortfügungen zu schmieden; dem Dichter ist es in gewissem Maße erlaubt; in keinem von beiden wird hier an Pflicht gedacht. Denn wer sich um den Ruf eines Redners bringen will, dem kann es niemand wehren. Es ist hier nur um den Unterschied der Imperativen unter problematischem, assertorischem und apodiktischem Bestimmungsgrunde zu thun. Eben so habe ich in derjenigen Note, wo ich die moralischen Ideen praktischer Vollkommenheit in verschiedenen philosophischen Schulen gegen einander stellte, die Idee der Weisheit von der der Heiligkeit unterschieden, ob ich sie gleich selbst im Grunde und objectiv für einerlei erklärt habe. Allein ich verstehe an diesem Orte darunter nur diejenige Weisheit, die sich der Mensch (der Stoiker) anmaßt, also subjectiv als Eigenschaft dem Menschen angedichtet. (Vielleicht könnte der Ausdruck Tugend, womit der Stoiker auch großen Staat trieb, besser das Charakteristische seiner Schule bezeichnen.) Aber der Ausdruck eines Postulats der reinen praktischen Vernunft konnte noch am meisten Mißdeutung veranlassen, wenn man damit die Bedeutung vermengte, welche die Postulate der reinen Mathematik haben, und welche apodiktische Gewißheit bei sich führen. Aber diese postuliren die Möglichkeit einer Handlung, deren Gegenstand man a priori theoretisch mit völliger Gewißheit als möglich voraus erkannt hat. Jenes aber postulirt die Möglichkeit eines Gegenstandes (Gottes und der Unsterblichkeit der Seele) selbst aus apodiktischen praktischen Gesetzen, also nur zum Behuf einer praktischen Vernunft; da denn diese Gewißheit der postulirten Möglichkeit gar nicht theoretisch, mithin auch nicht apodiktisch, d. i. in Ansehung des Objects erkannte Nothwendigkeit, sondern in Ansehung des Subjects zu Befolgung ihrer objectiven, aber praktischen Gesetze nothwendige Annehmung, mithin blos nothwendige Hypothesis ist. Ich wußte für diese subjective, aber doch wahre und unbedingte Vernunftnothwendigkeit keinen besseren Ausdruck auszufinden.
6 Namen, welche einen Sectenanhang bezeichnen, haben zu aller Zeit viel Rechtsverdrehung bei sich geführt; ungefähr so, als wenn jemand sagte: N. ist ein Idealist. Denn ob er gleich durchaus nicht allein einräumt, sondern darauf dringt, daß unseren Vorstellungen äußerer Dinge wirkliche Gegenstände äußerer Dinge correspondiren, so will er doch, daß die Form der Anschauung derselben nicht ihnen, sondern nur dem menschlichen Gemüthe anhänge.
Musean translation
Complete machine-assisted translation directly from Kant's German, Akademie-Ausgabe V (1913), pages 1–163, including all eighteen author notes. Original page and section references are retained.
Preface. A 3 V:3
Why this critique is not entitled a critique of pure practical reason, but simply of practical reason in general, although its parallel with speculative reason seems to require the former title, is sufficiently explained in this treatise. Its sole aim is to establish that there is pure practical reason, and for this purpose it subjects reason's entire practical faculty to criticism. If it succeeds, there is no need to criticize the pure faculty itself to see whether reason, in claiming such a faculty, is merely presuming to overstep its bounds, as speculative reason does. For if reason, as pure reason, is actually practical, it proves its own reality and that of its concepts by the deed itself, and all quibbling against the possibility of its being practical is futile.
With this faculty, transcendental freedom is now also A 4 established, in precisely the absolute sense in which speculative reason needed it when using the concept of causality. Speculative reason required freedom to escape the antinomy into which it inevitably falls when it seeks to think the unconditioned in the series of causal connections. Yet it could put forward this concept only problematically, as something not impossible to think, without securing its objective reality. Its sole purpose was to prevent the alleged impossibility of what it must at least admit as thinkable from undermining its own essential character and casting it into an abyss of skepticism.
The concept of freedom, insofar as its reality is proved by an apodictic law of practical reason, now forms the keystone of the entire structure of a system of pure reason, even speculative V:4 reason. All the other concepts—those of God and immortality—which remain unsupported in speculative reason as mere ideas, now attach themselves to it, and with it and through it acquire stability and objective reality. That is, their possibility is thereby A 5 proved by the actuality of freedom; for this idea reveals itself through the moral law.
Freedom is also the only one of all the ideas of speculative reason whose possibility we know a priori, without, however, having insight into it, because it is the condition1 of the moral law, which we know. The ideas of God and immortality, by contrast, are not conditions of the moral law, but only conditions of the necessary object of a will determined by that law—that is, of the A 6 merely practical use of our pure reason. We therefore cannot claim, regarding those ideas, to know or have insight into, I will not say merely their actuality, but even their possibility. Nevertheless, they are the conditions for applying the morally determined will to its object, given to it a priori: the highest good. Their possibility can and must therefore be assumed in this practical relation, without our knowing it or having insight into it theoretically. For this latter requirement, it is sufficient for practical purposes that they contain no internal impossibility, no contradiction. Here, then, is a ground for holding something true that, compared with speculative reason, is merely subjective, yet is objectively valid for a reason that is just as pure, though practical. Through the concept of freedom, this ground gives the ideas of God and immortality objective reality and warrants our assuming them—indeed, makes that assumption subjectively necessary, as a need of pure reason. Reason's theoretical cognition is not thereby V:5 extended. Rather, their possibility, previously only a problem, is here established as an assertion, and the practical A 7 use of reason is thus connected with the elements of its theoretical use. This need is not a hypothetical one serving some optional speculative purpose, as though we had to assume something if we wished to rise to a complete speculative use of reason. It is a need imposed by law: we must assume something without which that which we ought unfailingly to make the purpose of our conduct, in action and restraint alike, cannot come about.
It would certainly be more satisfying to our speculative reason to solve those problems on its own, without this detour, and to preserve their solution as an insight available for practical use. But our faculty of speculation is simply not so well equipped. Those who boast of such lofty cognitions should not withhold them, but present them publicly for examination and appreciation. They wish to prove them: very well, let them prove them, and the critique will lay its entire armor at their feet as victors. Why do you stand still? They are unwilling. And yet they may be happy.—Since in fact they are unwilling, presumably because they are unable, we must once again take up the critique A 8 to seek the concepts of God, freedom, and immortality in the moral use of reason, and ground them upon it, since speculation cannot provide a sufficient guarantee of their possibility.
Only here does the puzzle of the critique become clear: how we can deny objective reality to the supersensible use of the categories in speculation, yet grant them this reality in relation to the objects of pure practical reason. For before this it must necessarily appear inconsistent, so long as such a practical use is known only by name. But a complete analysis of that use now shows that the reality in question involves no theoretical determination of the categories and no extension of cognition to the supersensible. It means only that in this relation an object belongs to them in every case, because they are either contained in the necessary determination of the will a priori or inseparably connected with its object. That inconsistency then disappears, because A 9 we are using those concepts differently from the way speculative reason V:6 requires. Instead, a highly satisfying confirmation, scarcely to be expected beforehand, now emerges of the consistency of thought in the speculative critique. That critique insisted that the objects of experience as such, including our own subject, must count only as appearances, yet that things in themselves must underlie them; it therefore insisted that not everything supersensible be treated as an invention, nor its concept as empty of content. Now practical reason, independently and without having reached any agreement with speculative reason, gives reality to a supersensible object of the category of causality, namely freedom—although, as a practical concept, only for practical use. It thus confirms by a fact what could only be thought there. At the same time, the strange, though indisputable, claim of the speculative critique that even the thinking subject is, to itself, in inner intuition, merely an appearance, receives its full confirmation in the critique of practical reason. This confirmation is so complete that we would have to arrive at that claim A 10 even if the former critique had never proved it.2
This also enables me to understand why the most substantial objections to the critique that I have so far encountered turn precisely on these two hinges: on the one hand, the objective reality of the categories applied to noumena, denied in theoretical cognition and affirmed in practical cognition; on the other, the paradoxical demand that we make ourselves, as subjects of freedom, noumena, yet at the same time, with regard to nature, phenomena in our own empirical consciousness. For as long as no definite concepts of morality and freedom had been formed, one could not guess A 11 what was meant to underlie the supposed appearance as a noumenon, or, on the other side, whether it was possible to form any concept of it at all, if all the concepts of the pure understanding in theoretical use had already been assigned exclusively to mere appearances. Only a detailed critique of practical V:7 reason can remove all this misinterpretation and bring into clear light the consistency of thought that constitutes its greatest merit.
So much to justify why the concepts and principles of pure speculative reason, although already subjected to their own special critique, are here and there examined again in this work. Such reexamination would otherwise hardly be appropriate to the systematic progress of a science being established, since matters already decided should properly be cited, not reopened. Yet here it was permissible, indeed necessary, because reason is considered with those concepts in transition to a wholly different use from the one it made of them there. Such a transition requires a comparison A 12 of the earlier use with the new one, both to distinguish the new track clearly from the old and to make their connection evident. Reflections of this kind, including those directed once more to the concept of freedom, but now in the practical use of pure reason, should therefore not be regarded as interpolations serving merely to fill gaps in the critical system of speculative reason—for that system is complete for its purpose—or as props and buttresses added afterward, as happens with a hastily erected building. They are genuine members that make the coherence of the system visible, allowing concepts that could there be presented only problematically to be understood now in their actual exhibition. This reminder concerns above all the concept of freedom. It is surprising to observe how many still boast that they understand it perfectly and can explain its possibility, considering it merely in its psychological relation. If they had first examined it carefully in its transcendental relation, they would have recognized both A 13 its indispensability, as a problematic concept, to the complete use of speculative reason, and its utter incomprehensibility. On subsequently passing with it to practical use, they would then have arrived of their own accord at precisely the same determination of that use with respect to its principles that they are otherwise so reluctant to accept. The concept of freedom is the stumbling block for all empiricists, but also the key to the highest practical principles for critical moralists, who thereby V:8 understand that they must necessarily proceed rationally. I therefore ask the reader not to pass over with a cursory glance what is said about this concept at the close of the Analytic.
Whether a system of pure practical reason such as the one developed here from the critique of the latter has required much or little labor, particularly to avoid missing the correct standpoint from which its whole can be accurately laid out, I must leave to those familiar with such work to judge. It does presuppose A 14 the Groundwork of the Metaphysics of Morals, but only insofar as that work provides a preliminary acquaintance with the principle of duty and states and justifies a definite formula of it.3 Otherwise, it stands on its own. There is also a sound reason, in the character of this practical rational faculty, why a division of all the practical sciences has not been added for the sake of completeness, as it was in the critique of speculative reason. For duties can be specifically determined as human duties, and thus classified, only if the subject of this determination A 15—the human being—has first been known in its actual constitution, though only to the extent required in relation to duty in general. That knowledge, however, does not belong to a critique of practical reason in general, whose task is only to state completely the principles of its possibility, scope, and limits, without any special reference to human nature. The division therefore belongs here to the system of the science, not to the system of the critique.
In the second chapter of the Analytic I hope to have answered a certain truth-loving and acute, and so nonetheless always worthy of respect, reviewer of that Groundwork of the Metaphysics of Morals, concerning his objection that the concept of V:9 the good was not established there before the moral principle, as in his opinion it should have been.4 I have likewise A 16 taken account of several other objections that have reached me from men A 17 who show that discovering the truth is close to their hearts. For those who keep only their old system A 18 in view, and have already decided what is to be approved or disapproved, do not desire a discussion that might stand in the way of their V:10 private purpose. I will continue to proceed in this way.
When the task is to determine a particular faculty of the human soul in its sources, content, and limits, the nature of human cognition requires us to begin with its parts, giving an exact and, so far as the present state of the elements we have already acquired permits, complete account of them. But a second concern is more philosophical and architectonic: to grasp correctly the idea of the whole and, from it, to consider all those parts in their reciprocal relations by deriving them from the concept of that whole within a pure rational faculty. This examination and assurance are possible only A 19 through the closest familiarity with the system. Those who have found the first inquiry wearisome, and thus have not thought it worth the trouble to acquire this familiarity, do not reach the second stage: the comprehensive view that synthetically returns to what was previously given analytically. It is no wonder that they find inconsistencies everywhere, although the gaps that seem to suggest these are not in the system itself, but merely in their own disconnected train of thought.
With regard to this treatise, I have no fear of being accused of seeking to introduce a new language, since the kind of cognition involved here naturally approaches general accessibility. Nor could that accusation have occurred to anyone concerning the first critique who had not merely leafed through it but thought it through. To contrive new words where language already has no shortage of expressions for given concepts A 20 is a childish attempt to distinguish oneself from the crowd, if not by new and true thoughts, then by a new patch on an old garment. If, therefore, readers of that work know more accessible expressions that are nevertheless as adequate to the thought as those I have used seem to me, or if they believe they can demonstrate the emptiness of those thoughts themselves, and consequently of every expression designating them, they would oblige me greatly in the first case, for I wish only to be understood; in the second, they would render a service to philosophy. But as long as those thoughts still stand, V:11 I very much doubt that expressions both adequate to them and more familiar will be found.5
V:12 In this way, the a priori principles of two A 21 faculties of the mind, cognition and desire, would now have been discovered A 22 and determined in respect of the conditions, scope, and limits of their A 23 use. A secure foundation would thereby have been laid for a systematic philosophy, theoretical as well as practical, as a science.
What worse could befall these efforts than someone's unexpected discovery that there is no a priori cognition at all, nor can there be? Yet there is no danger of this. It would amount to someone's wishing to prove by reason that there is no reason. For we say that we know something through reason only when we are conscious that we could have known it even if it had not occurred to us in experience in that way. Rational cognition and a priori cognition A 24 are therefore one and the same. To try to squeeze necessity out of an experiential proposition—water from pumice—and thereby give a judgment true universality as well, is a direct contradiction. Without such universality there is no rational inference, not even inference by analogy, which amounts to at least a presumed universality and objective necessity, and therefore always presupposes them. To substitute subjective necessity, that is, habit, for the objective necessity found only in a priori judgments is to deny reason the capacity to judge an object—that is, to know it and what belongs to it. For example, concerning something that has frequently and invariably followed a certain preceding state, we could not say that we can infer the following event from the preceding state, since that would signify objective necessity and the concept of an a priori connection. We could only expect similar cases, much as animals do. This is at bottom to reject the concept of a cause as false and as a mere deception of thought. An attempt to remedy this lack of objective A 25 and consequently universal validity by saying that we see no reason to ascribe a different way of representing things to other rational beings would, if it were a valid inference, mean that our ignorance did more to extend our cognition than all our reflection. Merely because we know no rational beings other than human beings, we would have the right to assume that they are constituted as we know ourselves to be; that is, we would actually know them. I do not even mention here that universality in holding something true does not prove a judgment's objective V:13 validity, its validity as cognition. Even if such universality happened to occur, it still could not prove agreement with the object. Rather, objective validity alone provides the ground for a necessary universal agreement.
Hume, too, would find this system of universal empiricism A 26 in principles very congenial. As is well known, he required nothing more than the substitution of a merely subjective significance—habit—for all objective significance of necessity in the concept of a cause, in order to deny reason any judgment concerning God, freedom, and immortality. He certainly understood very well how to draw conclusions with complete logical rigor once his principles were granted. Yet even Hume did not make empiricism so universal as to include mathematics. He held its propositions to be analytic. If that were correct, they would indeed be apodictic, but no inference could be drawn from them to reason's capacity to make apodictic judgments in philosophy as well—namely, synthetic ones, such as the principle of causality. But if empiricism in principles were accepted universally, mathematics too would be caught up in it.
If mathematics now conflicts with a reason that admits only empirical principles A 27—as inevitably happens in the antinomy, where mathematics irrefutably proves the infinite divisibility of space, but empiricism cannot allow it—then the greatest possible evidence of demonstration stands in open contradiction to the supposed inferences from principles of experience. We must then ask, like Cheselden's blind man, what deceives me, sight or touch? For empiricism rests on a felt necessity, rationalism on one grasped through insight. Universal empiricism thus reveals itself as the genuine skepticism that was falsely attributed to Hume in so unrestricted a sense,6 since Hume at least left mathematics as a reliable touchstone for experience, A 28 V:14 whereas universal empiricism permits absolutely no such touchstone, which can always be found only in a priori principles, even though experience consists not merely of feelings but also of judgments.
Yet since, in this philosophical and critical age, that empiricism can hardly be seriously intended, and is presumably advanced only to exercise the power of judgment and, through contrast, bring the necessity of rational a priori principles into clearer light, we may still be grateful to those willing to undertake this otherwise not especially instructive labor.
1 To prevent anyone from supposing that there is an inconsistency here, when I now call freedom the condition of the moral law and later in the treatise maintain that the moral law is the condition under which we can first become conscious of freedom, I wish only to point out that freedom is indeed the ratio essendi of the moral law, while the moral law is the ratio cognoscendi of freedom. For if the moral law were not first distinctly thought in our reason, we would never consider ourselves entitled to assume anything such as freedom, even though it contains no contradiction. But if there were no freedom, the moral law would not be found in us at all.
2 Causality as freedom and causality as natural mechanism—the former established by the moral law, the latter by the law of nature, in one and the same subject, the human being—cannot be united unless that subject is represented, in relation to the former, as a being in itself, and in relation to the latter, as an appearance: in the first case in pure, in the second in empirical consciousness. Without this, reason's contradiction with itself is unavoidable.
3 A reviewer who wished to find something to criticize in that work struck nearer the truth than he himself may have intended when he said that it established no new principle of morality, but only a new formula. Who would wish to introduce a new principle of all morality and, as it were, invent it for the first time? As though before him the world had been ignorant or entirely mistaken about what duty is. But anyone who knows what a formula means to a mathematician—a precise determination of what must be done to carry out a given task, which leaves no room for error—will not regard a formula that does this for all duty in general as something insignificant and dispensable.
4 Someone might further object that I have not first explained the concept of the faculty of desire or of the feeling of pleasure. This objection would be unfair, since one should reasonably be able to presuppose such an explanation as already given in psychology. Yet the definition there might indeed be framed so as to make the feeling of pleasure the basis for determining the faculty of desire, as in fact commonly happens. This would necessarily make the supreme principle of practical philosophy empirical, which is precisely what must first be decided and is thoroughly refuted in this critique. I will therefore give the explanation here in the form required to leave this disputed point properly undecided at the outset.—Life is a being's capacity to act according to laws of the faculty of desire. The faculty of desire is its capacity to be, through its representations, the cause of the actuality of the objects of those representations. Pleasure is the representation of the agreement of an object or an action with the subjective conditions of life, that is, with the capacity for the causality of a representation with respect to the actuality of its object, or for determining the subject's powers to the action that produces it. For the purposes of the critique, I need nothing further among the concepts borrowed from psychology; the critique itself supplies the rest. It is easy to see that this explanation leaves undecided whether pleasure must always underlie the faculty of desire, or whether, under certain conditions, it merely follows that faculty's determination. For the explanation consists entirely of marks of the pure understanding, that is, categories, which contain nothing empirical. Such caution is highly advisable throughout philosophy, yet is often neglected: we should not anticipate our judgments with a venturesome definition before the concept has been fully analyzed, an achievement often reached only very late. Throughout the critique, of both theoretical and practical reason, one will also notice many opportunities to remedy defects in philosophy's old dogmatic procedure and correct errors that become apparent only when concepts are put to a use of reason directed toward reason as a whole.
5 More than that unintelligibility, I fear here and there a misinterpretation of certain expressions that I chose with the greatest care to prevent their intended concept from being missed. Thus, under the heading of modality in the table of categories of practical reason, the permitted and the forbidden—what is practically and objectively possible and impossible—mean almost the same thing in ordinary usage as the immediately following category of duty and what is contrary to duty. Here, however, the former is to signify what agrees or conflicts with a merely possible practical prescription, as with the solution of all problems in geometry and mechanics; the latter, what stands in that relation to a law actually present in reason in general. This distinction in meaning is not wholly foreign to ordinary usage, though somewhat unusual. For example, a speaker as such is forbidden to coin new words or combinations of words, while a poet is to some extent permitted to do so. Duty is not in question in either case. For no one can prevent someone who wishes to ruin his reputation as a speaker from doing so. What is at issue here is only the distinction between imperatives according to a problematic, assertoric, or apodictic determining ground. Likewise, in the note where I contrasted the moral ideas of practical perfection in different philosophical schools, I distinguished the idea of wisdom from that of holiness, although I myself declared them fundamentally and objectively one and the same. But in that passage I understand only the wisdom a human being, the Stoic, claims for himself: something therefore subjectively ascribed to the human being as a quality. Perhaps virtue, an expression of which the Stoic also made a great display, would better designate his school's distinctive character. The expression postulate of pure practical reason, however, might give rise to misinterpretation most of all if its meaning were confused with that of the postulates of pure mathematics, which carry apodictic certainty. These postulate the possibility of an action whose object has already been theoretically known a priori, with complete certainty, as possible. The former, by contrast, postulates the possibility of an object itself—God and the immortality of the soul—on the basis of apodictic practical laws, and thus solely for the purposes of a practical reason. The certainty of this postulated possibility is therefore not theoretical at all, and consequently not apodictic: it is not a necessity known with regard to the object, but an assumption necessary for the subject's observance of reason's objective, though practical, laws, and thus a merely necessary hypothesis. I could find no better expression for this subjective, yet true and unconditional, necessity of reason.
6 Names denoting allegiance to a school have always involved much distortion of what is rightfully someone's position, much as when someone says, N. is an idealist. For although he not only concedes but insists that actual objects of external things correspond to our representations of external things, he nevertheless maintains that the form of our intuition of them belongs not to those things but only to the human mind.
Plain English translation
Complete machine-assisted Plain English translation made independently and directly from the same German text, including all eighteen author notes.
Preface. A 3 V:3
This work explains well enough why its title is a critique of practical reason in general, rather than of pure practical reason. Its parallel with the critique of speculative reason might seem to call for the latter title. It only aims to show that there is pure practical reason. For this purpose, it critically examines reason's whole practical capacity. If it succeeds, it does not need to criticize the pure capacity itself to see whether reason oversteps its limits by claiming such a capacity as a mere presumption, as speculative reason does. For if reason really is practical as pure reason, it proves its own reality and that of its concepts by what it does. All quibbling against the possibility of its being practical is then pointless.
This capacity also establishes transcendental freedom A 4 in the absolute sense that speculative reason needed when using the concept of causality. It needed freedom to escape the antinomy it inevitably encounters when it tries to think of the unconditioned in the series of causal connections. But it could present this concept only as a possibility, as something not impossible to think. It could not establish its objective reality. Its only purpose was to keep reason from being challenged in its very nature and thrown into an abyss of skepticism by the supposed impossibility of something it must at least accept as thinkable.
The concept of freedom, insofar as its reality is proved by an absolutely certain law of practical reason, now forms the keystone of the whole structure of a system of pure reason, even speculative V:4 reason. All the other concepts—those of God and immortality—which remain unsupported in speculative reason as mere ideas, now connect with freedom. With it and through it they gain stability and objective reality. That is, their possibility is A 5 proved by the fact that freedom is actual. For this idea reveals itself through the moral law.
Freedom is also the only idea of speculative reason whose possibility we know a priori, although we have no insight into it. This is because freedom is the condition1 of the moral law, which we do know. The ideas of God and immortality, however, are not conditions of the moral law. They are only conditions of the necessary object of a will determined by this law—that is, of the A 6 purely practical use of our pure reason. So we cannot claim to cognize or understand even the possibility of these ideas, let alone their actuality. Still, they are conditions for applying the morally determined will to its object, which is given to it a priori: the highest good. Consequently, their possibility can and must be assumed in this practical relation, although we do not cognize or understand it theoretically. For this last requirement, it is enough for practical purposes that they contain no internal impossibility (contradiction). Here, then, is a ground for holding something true that is merely subjective when compared with speculative reason, yet objectively valid for an equally pure, but practical, reason. Through the concept of freedom, this gives the ideas of God and immortality objective reality, and gives us warrant, indeed a subjective necessity—a need of pure reason—to assume them. This does not expand reason's V:5 theoretical cognition. Instead, it supplies the possibility that was previously only a problem but is now an assertion. In this way it links the practical A 7 use of reason with the elements of its theoretical use. This need is not a hypothetical one serving some optional speculative purpose: that we must assume something if we want to complete reason's use in speculation. It is a need imposed by a law: to assume something without which we cannot achieve what we ought unfailingly to make the purpose of our conduct.
It would certainly satisfy our speculative reason more to solve these problems on its own, without this detour, and keep the resulting insight for practical use. But our capacity for speculation simply is not that capable. Those who boast of such lofty cognitions should not keep them to themselves. They should present them publicly for examination and appreciation. They want to prove them. Very well! Let them do so, and the Critique will lay all its weapons at their feet as victors. Why do you stand still? They are unwilling. Yet they could be happy.—Since they do not in fact want to, presumably because they cannot, we must take up the Critique again A 8. We must seek the concepts of God, freedom, and immortality in the moral use of reason and ground them on it, since speculation cannot adequately guarantee their possibility.
Only here does the puzzle of the Critique become clear. How can we deny objective reality to the supersensible use of the categories in speculation, yet grant them this reality in relation to the objects of pure practical reason? This must seem inconsistent as long as we know such a practical use only by name. But a full analysis of that use now shows us something else. The reality in question does not amount to any theoretical determination of the categories or any extension of cognition into the supersensible. It means only that in this relation they have an object at all. For they are either contained a priori in the necessary determination of the will or inseparably connected with its object. The inconsistency disappears, because A 9 these concepts are being used differently from the way speculative reason V:6 requires. In fact, a very satisfying confirmation of the speculative Critique's consistency of thought now appears, one we could hardly have expected. That Critique insisted that objects of experience as such, including our own subject, must count only as appearances. Yet it also insisted that things in themselves must underlie them, so that not everything supersensible should be treated as fiction or its concept as empty of content. Now practical reason, independently and without arranging anything with speculative reason, gives reality to a supersensible object of the category of causality, namely freedom. As a practical concept, it does so only for practical use. It thus confirms by a fact what previously could only be thought. At the same time, the strange but indisputable claim of the speculative Critique—that even the thinking subject is, to itself, merely an appearance in inner intuition—is fully confirmed in the Critique of Practical Reason. Indeed, we would have to arrive at it A 10 even if the former had never proved it.2
This also explains why the most important objections to the Critique that I have encountered so far hinge on precisely these two points. On the one hand, the objective reality of categories applied to noumena is denied in theoretical cognition but asserted in practical cognition. On the other, there is the paradoxical demand that we regard ourselves as noumena insofar as we are subjects of freedom, but also as phenomena in our own empirical consciousness insofar as we belong to nature. As long as people had no definite concepts of morality and freedom, they could not guess what A 11 was supposed to underlie the alleged appearance as a noumenon. Nor could they tell whether it was possible to form a concept of it at all, if all the concepts of pure understanding in their theoretical use had already been assigned exclusively to mere appearances. Only a detailed critique of practical V:7 reason can remove all these misunderstandings. It can bring into clear view the consistency of thought that is precisely the Critique's greatest merit.
That is my justification for sometimes reexamining in this work the concepts and principles of pure speculative reason, even though they have already undergone their own critique. This would not normally suit the systematic development of a science being established. Matters already decided should properly be cited, not reopened. But here it was permissible, even necessary, because reason is being considered as it moves to an entirely different use of those concepts from the use it made of them there. Such a transition requires comparing A 12 the earlier use with the new one. We need to distinguish the new path clearly from the old and also show how they connect. So reflections of this kind—including the renewed discussion of freedom, but now in the practical use of pure reason—should not be seen as insertions intended merely to fill gaps in the critical system of speculative reason. That system is complete for its purpose. Nor are they supports and buttresses added afterward, as happens with a building put up too hastily. They are genuine connecting parts that show the system's coherence. They make it possible to understand concepts in their actual presentation that previously could only be represented as possibilities. This reminder chiefly concerns the concept of freedom. It is surprising that so many people still boast that they understand it perfectly well and can explain its possibility, while considering it only in a psychological relation. If they had first examined it closely in its transcendental relation, they would have recognized both A 13 its indispensability as a problematic concept in the full use of speculative reason and its complete incomprehensibility. Had they then moved to its practical use, they would have arrived on their own at exactly the same account of that use and its principles which they otherwise accept so unwillingly. The concept of freedom is the stumbling block for all empiricists. But it is also the key to the highest practical principles for critical moral philosophers, who thereby V:8 see that their procedure must be rational. I therefore ask readers not to skim what is said about this concept at the end of the Analytic.
I must leave those familiar with this kind of work to judge whether developing such a system of pure practical reason from its critique has required much effort or little. The chief concern was not to miss the right standpoint from which the whole could be accurately mapped out. It does presuppose A 14 the Groundwork of the Metaphysics of Morals, but only insofar as that work gives a preliminary acquaintance with the principle of duty and provides and justifies a definite formula for it.3 In other respects it stands on its own. There is also a sound reason, in the nature of this practical capacity of reason, why a division of all practical sciences has not been included for completeness, as it was in the Critique of Speculative Reason. That is because, to classify duties by specifically determining them as human duties, we must first know the subject of that determination A 15—the human being—as it actually is, though only to the extent needed for duty in general. But this does not belong in a critique of practical reason in general. Such a critique must fully state the principles of its possibility, scope, and limits without special reference to human nature. The division therefore belongs here to the system of the science, not to the system of its critique.
In the second chapter of the Analytic, I hope I have answered a certain sharp, truth-loving, and therefore always respectable reviewer of that Groundwork of the Metaphysics of Morals. He objected that the concept of the V:9 good had not been established there before the moral principle, as he thought necessary.4 I have also taken account of A 16 various other objections sent to me by men A 17 who show that discovering the truth matters to them (for those who keep only their old system A 18 in view, and have already decided what to approve or disapprove, do not want a discussion that might obstruct their V:10 private aim). I will continue to proceed in this way.
When defining a particular capacity of the human soul in terms of its sources, content, and limits, the nature of human cognition requires us to start with its parts. We must present them precisely and as completely as our current stock of established elements allows. But a second consideration is more philosophical and architectonic. We must correctly grasp the idea of the whole. From it, we must view all those parts in their mutual relations by deriving them from the concept of that whole within a capacity of pure reason. This examination and confirmation is possible only A 19 through the closest familiarity with the system. Those who have been reluctant to undertake the first investigation, and so have not thought this familiarity worth acquiring, never reach the second stage: the overview. This is a synthetic return to what was previously given analytically. No wonder they find inconsistencies everywhere. The gaps these seem to suggest are not in the system itself, but only in their own disconnected train of thought.
For this work, I have no fear of being accused of trying to introduce a new language, because the kind of cognition here naturally comes closer to ordinary understanding. Nor could anyone have thought of making that accusation against the first Critique if they had thought it through rather than merely leafed through it. Making up new words where the language already has no shortage A 20 of expressions for the concepts concerned is a childish effort to stand out from the crowd. If not through new and true thoughts, then at least through a new patch on an old coat. So if readers of that work know more familiar expressions that fit the thought just as well as mine seem to me to do, they would do me a great favor by supplying them, for I only want to be understood. Or if they think they can demonstrate that these thoughts themselves are worthless, and therefore so is every expression designating them, they would render a service to philosophy. But as long as those thoughts stand, V:11 I very much doubt that more familiar expressions equally suited to them can be found.5
V:12 In this way the a priori principles of two A 21 capacities of the mind—the cognitive faculty and the faculty of desire—would now have been established A 22 and defined in terms of the conditions, scope, and limits of their A 23 use. A secure foundation would thereby have been laid for systematic philosophy as a science, both theoretical and practical.
What worse thing could happen to these efforts than someone's unexpected discovery that there is, and can be, no a priori cognition at all? But there is no danger of that. It would be like trying to prove through reason that there is no reason. For we say we cognize something through reason only when we are aware that we could have known it even if we had not encountered it in experience as we did. Cognition through reason and a priori cognition A 24 therefore mean the same thing. Trying to squeeze necessity out of a proposition based on experience—water from a pumice stone—and with it give a judgment true universality, is a direct contradiction. Without that universality there is no inference of reason, including inference by analogy, which involves at least presumed universality and objective necessity and therefore always presupposes them. Substituting subjective necessity, or habit, for objective necessity, which occurs only in a priori judgments, means denying reason the capacity to judge the object: to cognize it and what belongs to it. For example, when something has often and always followed a certain previous state, we could not say that we can infer the one from the other. That would imply objective necessity and the concept of an a priori connection. We could only expect similar cases, much as animals do. This means rejecting the concept of cause as fundamentally false, a mere deception of thought. Suppose we tried to remedy this lack of objective A 25 and consequently universal validity by saying that we see no reason to attribute a different way of representing things to other rational beings. If that were a valid inference, our ignorance would do more to expand our cognition than all our reflection. For merely because we know no rational beings other than humans, we would be entitled to assume that their nature is the same as the nature we know in ourselves. In other words, we would actually know them. I will not even dwell on the point that universal acceptance of a judgment does not prove its objective V:13 validity—its validity as cognition. Even if such agreement happened to occur, it could not prove agreement with the object. Rather, objective validity alone provides the ground for necessary universal agreement.
Hume would also feel quite at home with this system of universal empiricism A 26 in principles. For, as is well known, he asked only that the concept of cause should contain a merely subjective necessity, namely habit, instead of any objective meaning of necessity, so as to deny reason any judgment about God, freedom, and immortality. He certainly knew very well how to draw conclusions with complete logical rigor once his principles were granted. But even Hume did not make empiricism so universal as to include mathematics. He regarded its propositions as analytic. If that were correct, they would indeed be absolutely certain. Yet this would not allow us to infer that reason can also make absolutely certain judgments in philosophy—synthetic ones, such as the principle of causality. But if empiricism about principles were accepted universally, mathematics would be included too.
Now suppose mathematics conflicts with a reason that admits only empirical principles A 27. This is inevitable in the antinomy, since mathematics proves the infinite divisibility of space beyond dispute, while empiricism cannot allow it. Then the greatest possible certainty of demonstration openly contradicts the supposed inferences from principles of experience. We must then ask, like Cheselden's blind man: which is deceiving me, sight or touch? For empiricism rests on a necessity that is felt, while rationalism rests on one that is understood. Universal empiricism thus reveals itself as the genuine skepticism that was wrongly attributed to Hume in so unrestricted a sense,6 since he at least left mathematics as a reliable touchstone of experience A 28 V:14. Universal empiricism, by contrast, permits no touchstone of experience at all. Such a touchstone can be found only in a priori principles, although experience consists not merely of feelings but also of judgments.
Still, in this philosophical and critical age, this kind of empiricism can hardly be meant seriously. Presumably it is proposed only to exercise judgment and, through contrast, to bring the necessity of rational a priori principles into clearer view. We can therefore thank those who are willing to undertake this otherwise not especially instructive work.
1 To prevent anyone from imagining inconsistencies here, I will add a reminder. I now call freedom the condition of the moral law, but later in this work I claim that the moral law is the condition under which we can first become conscious of freedom. Freedom is indeed the ground of being of the moral law, while the moral law is the ground of knowing freedom. For if the moral law were not first clearly thought in our reason, we would never consider ourselves entitled to assume anything like freedom, even though freedom involves no contradiction. But if there were no freedom, the moral law could not be found in us at all.
2 Causality as freedom and causality as natural mechanism are established in one and the same subject, the human being: the first through the moral law, the second through the law of nature. Combining them is impossible unless we represent the human being as a being in itself in relation to the first, and as an appearance in relation to the second—the former in pure consciousness, the latter in empirical consciousness. Without this, reason's contradiction with itself is unavoidable.
3 A reviewer who wanted to criticize this work came closer to the truth than he may have intended. He said that it presented no new principle of morality, but only a new formula. But who would want to introduce a new principle of all morality, as though inventing it for the first time? That would be as if the world before him had known nothing about duty or had been thoroughly mistaken about it. Anyone who knows what a formula means to a mathematician—one that determines exactly what to do to solve a problem and prevents mistakes—will not regard a formula that does this for all duty in general as insignificant or unnecessary.
4 Someone might also object that I did not first explain the concept of the faculty of desire or of the feeling of pleasure. This would be unfair, since we should properly be able to presuppose the explanation given in psychology. Yet that definition might make the feeling of pleasure the basis for determining the faculty of desire, as in fact is usually done. This would necessarily make the supreme principle of practical philosophy empirical. But that is precisely what must first be decided, and this Critique completely refutes it. So I will give the explanation here in the form needed to leave this disputed point undecided at the beginning, as it should be.—Life is a being's capacity to act according to laws of the faculty of desire. The faculty of desire is its capacity, through its representations, to cause the actuality of the objects of those representations. Pleasure is the representation of the agreement of an object or an action with the subjective conditions of life: that is, with the capacity for a representation to cause the actuality of its object, or to determine the subject's powers to act to produce it. I need no more than this for the critique of concepts borrowed from psychology. The Critique itself supplies the rest. It is easy to see that this explanation leaves undecided whether pleasure must always underlie the faculty of desire, or whether under certain conditions it may only follow that faculty's determination. For the explanation is composed entirely of features belonging to pure understanding, namely categories, which contain nothing empirical. Such care is highly advisable throughout philosophy, yet often neglected: we should not prejudge matters through a risky definition before fully analyzing the concept, an analysis often achieved only much later. Throughout the Critique of both theoretical and practical reason, readers will also find many opportunities to remedy shortcomings and correct errors in philosophy's old dogmatic procedure. These are noticed only when reason uses concepts in a way directed at reason as a whole.
5 Here I fear occasional misinterpretation of certain expressions more than incomprehensibility. I chose those expressions with the greatest care to keep their intended concept in view. In the table of categories of practical reason, under modality, the permitted and forbidden—what is practically and objectively possible and impossible—have almost the same meaning in ordinary speech as the next category, duty and what is contrary to duty. But here the first means what agrees or conflicts with a merely possible practical precept, such as the solution of all problems in geometry and mechanics. The second means what stands in that relation to a law actually present in reason in general. This difference in meaning is not wholly foreign to ordinary speech, though somewhat unusual. For example, a public speaker as such is forbidden to coin new words or phrases; a poet is permitted to do so to some extent. Neither case concerns duty. For no one can stop someone who wants to ruin his reputation as a speaker. The issue here is only the distinction between imperatives whose determining grounds are problematic, assertoric, and apodictic. Similarly, in the note where I compared the moral ideas of practical perfection in different philosophical schools, I distinguished the idea of wisdom from that of holiness, although I myself declared them fundamentally and objectively identical. But there I mean only the wisdom that a human being—the Stoic—claims to possess: wisdom subjectively attributed to a human being as a property. Perhaps virtue, another expression the Stoic made much of, would better describe his school's characteristic feature. But the expression postulate of pure practical reason could cause the most misunderstanding, if confused with the meaning of postulates in pure mathematics, which carry absolute certainty. Those postulate the possibility of an action whose object has already been theoretically cognized a priori, with complete certainty, as possible. A postulate of pure practical reason, however, postulates the possibility of an object itself—God and the soul's immortality—on the basis of absolutely certain practical laws, and thus only for the purposes of practical reason. Here the certainty of the postulated possibility is not theoretical, and therefore not apodictic: it is not necessity cognized with regard to the object. Instead, it is an assumption necessary for the subject to follow reason's objective but practical laws, and so merely a necessary hypothesis. I could find no better expression for this subjective yet genuine and unconditional necessity of reason.
6 Names designating allegiance to a school have always caused much unfair distortion. It is rather like someone saying: N. is an idealist. Although he not only fully admits but insists that actual objects of external things correspond to our representations of external things, he still maintains that the form of their intuition belongs not to them, but only to the human mind.
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