Barth’s includes an extensive treatment of Kant in his history of 19th century Protestant theology. According to Barth, Kant represents the 18th-century’s coming to self-consciousness. He saw both the possibilities and the limits of the Enlightenment’s obsessions with reason. He announces that his age is the age of criticism, but in Kant this criticism turns against itself. Kant does not critique certain propositions, but turns the critical apparatus of enlightenment on knowledge per se. The civilization achieved by the 18th century is beyond question, but he wants to “establish the method of his civilization: it seeks, in so far as this civilization is firstly and lastly that of the Enlightenment, to bring about an enlightenment of the Enlightenment about itself.” Kant trusts reason, but he wants to place trust in “the reason which has first of all come to be reasonable as regards itself.”
Kant sees the advances of the 18th century everywhere. Science is unlocking the truths of the natural world. The French Revolution demonstrates man’s capacity for social improvement. But this “boundless self-affirmation of reason . . . was ultimately bound to be uncertain of itself.” This self-affirmation, from Kant on, had to “bear with ‘being’ asked, whether it in fact rests upon a true maturity.” This is especially true for theology: “From now on theology would no longer be able to formulate its tenets, no matter on what foundation it might base them, without having acquired a clear conception of the method of reason, which it also uses in the construction of its tenets. Any theology which had not at least faced this question and presented its credentials was backward, from now own, superseded in its relation to the age.”
According to Barth, Kant’s critique of reason established basic trends that have a bearing on theology. The first was the insistence on “the ideal character of all knowledge achieved by pure reason.” Pure rational knowledge is “that necessary knowledge which refers not to what is, but to an object that transcends all experience, to what must be and only in this sense ‘is.’” This pure rational knowledge accompanies all experience and empirical knowledge, and thus is necessary, and it consists in the knowledge of the ideas of God, freedom, and immortality. Knowledge of ideas and of empirical objects is inseparable; knowledge is the unity of intuition and concepts. But we don’t have any knowledge in this sense of the things that lie outside empirical experience: “So far as the objects of intuition and the Understanding, of empirical knowledge, are concerned, God, Freedom, and Immortality are not objects of our knowledge,” that is, not of “our theoretical knowledge.” Theoretical proofs for God are thus useless, “for they apply the Category of being, positively and negatively, to an object which lacks intuition” (empirical availability). Hence, “God is a limiting concept, a regulative idea, a pure thing of thought.”
Bringing reason to self-consciousness, however, not only involves staking out the limits of theoretical reason, but also affirming the reality of active, practical reason. Practical reason is not a second kind of reason, but rather the same reason which is “primarily” practical. The union of intuition and concept is “in fact action, practice,” and it’s by this act that “man is laid hold of not only by the being of things, i.e. by nature in its reality in time and space, but beyond this and above all by the thing that must be, hidden from us as a ‘thing in itself.’” The truth of ideas is thus “practical truth, truth, that is, which is perceived in the form of such pre-suppositions (Kant says, in the form of ‘postulates’) which are accomplished in the moral act – the presuppositions of God, freedom, and immortality. Thus too “the proof of God is ever to be adduced as a demonstration of the presupposition that is assumed in deciding to accept the commandment of the inscrutable Law-giver.” True proofs of God must be “moral” proofs. The only knowledge of God is a practical one. In this, Kant is not attempting to destroy metaphysics, as some claim, but rather to raise metaphysics to the level of a science.
Kant, Barth points out, did not wait for theologians to make peace with his critique of reason, but offered his own terms of peace in Religion Within the Limits of Reasn and in Dispute of the Faculties. Barth sums Kant’s aim as a philosopher religion as a double one: “he wants on the one hand, as a philosopher, i.e. as the advocate of human reason in the general sense – which is seeking to understand itself and is thus self-critical – to remind religion too and theology as religion’s mouth-piece of the significance of the fact that it too is a matter in which reason places its part, an additional part, at all events, just as certainly as it too at least makes use of reason in the establishment of its propositions. And on the other hand, once again as a philosopher, he wants to assess religion as a phenomenon of reason, as a cultural manifestation . . . . he wants to make it intelligible within the frame-work of all the other phenomena of reason, to construct it by applying the general principles pertaining to all civilization.”
The reason within whose limits Kant discusses religion is not theoretical reason, but reason purified of revelation – reason alone in the sense that it accepts no revelation from God. Within the limits of this reason, the religion of reason is, according to Kant, morality represented as God-given, the practical obedience to duty as coming from a divine Law-giver. Revelation is an accommodation to the weakness of humanity, the need to have some concrete empirical ground for religious belief and practice. Kant reinterprets Christology, salvation, and ecclesiology within the limits of this reason. A theology that works within these limits, that translates its revealed faith into the dictates of pure religion, is at peace with Kantian philosophy.
Three possibilities arise for theology, according to Barth. First, some theologians simply accepted Kant and set out “to execute the Kantian programme.” That is, theologians might accept Kant at face value, and try to develop a theology that accepts Kant’s claims about the nature of “religion.” In this category, Barth includes Ritschl. Second, theology can accept Kant insofar as method, but “subject it to an immanent critique” in which it attempts “to broaden and enrich the conception of reason which forms the premise by pointing out that there is yet another capacity a priori which is part of the necessities of human reason, apart from the theoretical and practical ones: the capacity for feeling, as Schleiermacher put it.” This correction of Kant “became characteristic of the stamp of theology in the nineteenth century, and in particular, of the so-called conservative or positive theology, just as much as of the so-called liberal theology of the century. Both these first possibilities have it in common that theology desires in principle to keep to the Kantian terms for peace, and enter into negotiations, merely, with their dictator, whether it be upon the conditions he has laid down for their execution, or upon the actual terms for peace themselves.” In pursuing these developments, “nineteenth-century theology is destined to be the direct continuation of the theology of the Enlightenment.” Third, theology might question “not only the application of the Kantian conception of the problem, but that conception itself, and therefore the autocracy and its competence to judge human reason in relation to
the religious problem.” This would involve “theology resigning itself to stand on its own feet in relation to philosophy, in theology recognizing the point of departure for its method in revelation, just as decidedly as philosophy sees its point of departure in reason, and in theology conducting, therefore, a dialogue with philosophy, and not, wrapping itself up in the mantle of philosophy, a quasi-philosophical monologue.” Barth sees glimmers of this option arising in nineteenth-century theology, but thinks it was a largely untapped possibility.
The third option, of course, is the post-Kantian option that Barth himself followed, and he spends the last section of his chapter pondering whether “the prospect of this third possibility might really present itself even from Kant’s own standpoint.” He concludes, finally, that however ironically and mockingly Kant may have meant it, the force of his thought leads to an independent biblical theology alongside philosophy. And, while Kant may have seen the interaction between them as uni-directional, there is no reason why it cannot go both ways. Let me sum up Barth’s case for reading Kant this way. Kant is laying out the border between philosophy and theology, keeping each in its limits, but Barth suggests that he occasionally took a transgressive step over that border. He clearly imagines the possibility of a different sort of theology from the philosophical theology that he lays out, a theology that he describes as “biblical theology.”
When Kant discusses revelation, he does not deny the possibility that revelation might have occurred. What he denies is that revelation can be accounted for on the grounds of philosophy. He believes there can be a philosophy of religion, but not a philosophy of faith. Even when he discusses religion within the limits of reason, he doesn’t think that he has captured all that religion consists in. Barth quotes a letter in which Kant states that after reason has done its work to analyze religion philosophically, it “must await the arrival of everything else, which must be added beyond its capacity, without reason being permitted to know in what it consists, from the supernatural hand of heaven.” Kant elsewhere says “we do not dispute the miracles themselves, but merely leave them without restraint to the biblical theologian, in so far as he wishes to judge solely as a biblical theologian and scorns any alliance with philosophy.” Philosophy cannot establish revelation, but neither can it deny the possibility that Scripture has come by inspiration of God: “it might be after all that the teachings of revelation stem from men supernaturally inspired,” he says in the Dispute of the Faculties.
For Kant, “The biblical theologian is really the scribe of the Church faith, which rests upon statutes; laws, that is to say, which stem from the arbitrary choice of another authority.” Theology has its own domain – as Barth sums it, “the Church, the Bible, historical revelation, and grace” – and in this terrain philosophy ought not intrude. For the Biblical theologian, the proof that God exists is “the fact that he has spoken in the Bible.” Barth only regrets “that there was apparently no one among Kant’s theological contemporaries who had the insight, the courage and the humour expressly to draw the great man’s attention, in all respect, to the mutual quality of this relationship” between philosophy and biblical theology. Barth acknowledges the possibility that “with more than one of the passages just quoted Kant may have laughed up his sleeve as he wrote them, happy not to be in the shoes of such a ‘biblical theology.” Yet, Barth wants to insist that there is an insight here, a kind of declaration of independence for theology, which allows it its own basis and subject matter and methods that do not have to pass the test of reason. “It is not the case,” he closes, “that the philosopher of pure reason has said something very significant to the theologian in telling him in all succinctness that ‘The biblical theologian proves that God exists by means of the fact that he has spoken in the Bible’?”