Undoubtedly it is strange to hear that Hegel backs his absolute idealism on history and not on a purely rational or metaphysical argument. However, he is not proceeding differently from the other representatives of German Idealism.
Kant had already backed his transcendental idealism on the fact of science, in other words, on an event in human history. Kant claimed that there was no other possibility to explain the fact of science as a body of knowledge able to make accurate predictions about the future. Through his transcendental idealism, Kant develops a speculative theory about the human mind that can explain a fact of human history.
Transcendental idealism is thus not a theoretical option, or at least this is not how Kant presents it. Nevertheless, it is the only way to explain why science is possible. Therefore, Kant can claim that through the fact that science can be explained exclusively through the transcendental approach, this explanation is also proof that the transcendental approach is correct and that its metaphysical background, which separates things in things in themselves and phenomena, is correct too.
Thus what Kant introduced was the idea that philosophy must become a science itself, and, like any other science, its hypotheses must not stay in the rarefied medium of philosophical speculation but must be able to be verified through facts. This is what those who think that the correspondence between mind and reality can be, after Kant, a theoretical option, forget too easily.
Of course, a metaphysical idea cannot be proved in itself. What Kant accomplished, was not to prove it directly, but indirectly, through making intelligible – through that metaphysical hypothesis – a realm of human experience: science. In order to do this, he elaborated a whole new transcendental structure of the human mind, which he could then also relate to many domains of human life other than science, namely to morality, art, religion, or the Right.
All the interpretations of these other domains were backed themselves by the correctness of the explanation of the possibility of Newtonian science of nature. Kant thought that his new philosophical project would transform philosophy itself into a science; in fact, he really believed that it had indeed almost transformed it, since his first Critique offered most of the necessary elements for that science. He thus introduced into modernity the understanding of philosophy as science.
Indeed, philosophy has always been seen as a science or even as the queen of sciences. However, the old meaning of this scientific character of philosophy was different. It was based only on rational or logical arguments. However, rational arguments can easily be mistaken, and philosophers are often unable to notice their own errors.
This is why the history of philosophy and especially of metaphysics – its core part – is full of views that contradict each other. And such a state of facts was seen as a real scandal in Kant’s epoque, which could easily lead to a complete mistrust in any claims of metaphysics to offer true knowledge.
Thus, more than rational arguments was needed to transform philosophy into a science of the Newtonian kind, where such a mutual contradiction between scientists was no longer possible. In Newtonian science, scientists have been able to find a way to prove their hypotheses and to let others test that proof themselves. This way was called experiment.
If philosophy was to transform into certain knowledge, eliminating constant quarrels between its representatives, it had to find the sure path of science. Kant claims he discovered that path through the fact that he offered all other philosophers an experiment to test his purely rational hypothesis.
This experiment was the fact that only that way could the scientific predictions of Newtonian physics be understood as necessary predictions. In science, we do not simply generalize the past, as happens daily in our life. Our empirical generalizations lack the strong necessity and mathematical character of scientific knowledge.
Historically, Kant’s achievement, although considered epoch-making, raised many critiques, either because of internal contradictions, unclear arguments, or even the introduction of opaque terms. Yet, his claim concerning the necessity to transform philosophy into a science whose knowledge might be tested remained a requirement for a new ideal of philosophy.
Later, the philosophers of the so-called German Idealism took over this ideal of the scientificity of philosophy, each of them trying to find something like a philosopher’s stone that could prove their perspective. But in this endeavor, obviously, they took over from Kant most of his newly introduced concepts and ways of arguing.
The distinction between things in themselves and phenomena, Reason as a fundamental human faculty, or the categorical imperative, are only a few of the most famous concepts that had an impressive history after Kant.
How did these philosophers manage to adapt to the claim of the scientificity of philosophy? Each of them tried to show now that what one could meet in the empirical sphere of man was possible through their own approach.
Fichte, the first who diverged from the Kantian system, transformed it so that the contradictions so obvious in that system might be avoided. And one of the most problematic conceptual flaws in that system was the distinction between the thing in themselves and phenomena.
He tried to remove this distinction. But it was no longer possible to return to the old way of understanding the relationship between the human mind and reality after Kant. It was no longer possible to back human knowledge either on past generalizations or on the age-old theory of correspondence between the mind and reality. As Kant showed, neither of these options any longer allowed the explanation of Newtonian science.
Thus the new type of philosophy was faced with problems that Kant’s philosophy raised for the first time. The whole conceptual background that these philosophers developed had to confront those problems while also endeavoring to build a non-contradictory philosophical edifice.
Within the scope of the new philosophical approaches, the question of how all the aspects of human life – that could be met as factual realities – were possible, received an essential place.