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[¶9] Metaphysics - a wholly isolated speculative cognition of reason that elevates itself entirely above all instruction from experience, and that through mere concepts (not, like mathematics, through the application of concepts to intuition), where reason thus is supposed to be its own pupil - has up to now not been so favored by fate as to have been able to enter upon the secure course of a science, even though it is older than all other sciences, and would remain even if all the others were swallowed up by an all-consuming barbarism. For in it reason continuously gets stuck, even when it claims a priori insight (as it pretends) into those laws confirmed by the commonest experience. In metaphysics we have to retrace our path countless times, because we find that it does not lead where we want to go, and it is so far from reaching unanimity in the assertions of its adherents that it is rather a battlefield, and indeed one that appears to be especially determined for testing one's powers in mock combat; on this battlefield no combatant has ever gained the least bit of ground, nor has any been able to base any lasting possession on his victory. Hence there is no doubt that up to now the procedure of metaphysics has been a mere groping, and what is the worst, a groping among mere concepts.
[¶10] Now why is it that here the secure path of science still could not be found? Is it perhaps impossible? Why then has nature afflicted our reason with the restless striving for such a path, as if it were one of reason's most important occupations? Still more, how little cause have we to place trust in our reason if in one of the most important parts of our desire for knowledge it does not merely forsake us but even entices us with delusions and in the end betrays us! Or if the path has merely eluded us so far, what indications may we use that might lead us to hope that in renewed attempts we will be luckier than those who have gone before us?
Summary
Metaphysics has failed to become a secure science. It has constantly had to begin over again so that no advance has been made. However, if metaphysics were impossible, then we must wonder: why does our own nature seem to aim us in the direction of these problems?
Commentary
In this passage, metaphysics is both ridiculed and honored. On the one hand, metaphysics has failed as a science and is only suited for mock combat. Perhaps worst of all it is a science that deals merely in concepts that - unlike natural science or mathematics - cannot be exhibited anywhere: metaphysics seems to be a game for thought. On the other hand, metaphysics concerns problems that are of the highest moment for us, and so metaphysics is the oldest and most enduring science; it seems a product of our own nature calling out for answers. From this situation Kant faces a crisis: if metaphysics is really a dead end, then what can we say for ourselves since our very nature leads us down this blind alley? At some level, we cannot indict metaphysics without indicting the meaning of our existence.
While such a concern may seem to be merely motivating rhetoric for the critique, the consistency that this concern has with the type of solution Kant ultimately comes to give reason to believe it is not merely rhetoric. What if our own nature is subject to misinterpretation and our misunderstanding only shows itself later through contradictions that seem unavoidable? A paradigm shift resulting from a reinterpretation of our nature will be required to put us on the correct course. Kant's critique is designed to show the contradictions that have emerged naturally for us and present an option that avoids these issues. Furthermore, it will present a new option for interpreting our nature: that we are not meant to pursue knowledge of these metaphysical questions, but our nature is pushing us towards beliefs.
One more general note on the interpretation of our nature. This theme, which is akin to the maxim to "know thyself", contains an existentialist dimension of Kant. Here there is no grounding logical principle and instead one encounters a decision about the meaning of our lives that can change everything for us. Kant rarely works out these problems on the page, but it is worth pointing it out even just to show the limits of the scope of critical philosophy as well as to enable comparative philosophy that can deepen our insight (e.g., comparisons to Kierkegaard, Nietzsche, etc).
Terminology
speculative cognition of reason (spekulativen vernunfterkenntnis)