Since its publication in 1781, Immanuel Kant’s Critique of Pure Reason has established itself as one of the essential volumes in the history of philosophical literature. The complex work stands on its own as the equal of such other foundational tomes as Plato’s Republic, the Summa Theologica of Thomas Aquinas the arrival of the Nietzschean Ubermensch in Thus Spake Zarathustra.
While far too complex in subject matter and analysis for any short summary to do it justice, when all is said and done, what Kant is really aiming for in the summation of all his work and learning was reconciliation. Kant put his brilliant mind to the epistemological aspect of philosophy, which is the study of knowledge. Philosophy without knowledge is mere theory, but knowledge without an understanding of its meaning and how that meaning can and should be applied is the path to bad theory upon which bad philosophies are constructed.
The reconciliation that Kant seeks in the massive book, then, is that between the two theories of knowledge which had come to be predominant by the Age of Enlightenment: empiricism and rationalism. Kant came to stand in opposition to both the concept of any innate knowledge separated from experience and the insistence that all knowledge was utterly dependent upon experience. Since both Rationalists like Descartes and Empiricists like Locke were proceeding from fundamentally flawed theories, any philosophies constructed solely upon these theories were by definition also flawed. It is from this position Kant sought reconciliation between the two which would arrive at an understanding of the sources of all knowledge. The wording of his goal for Critique of Pure Reasons stands as one of the most accessible formulations to be found in the book: “Although all our knowledge begins with experience, it does not follow that it arises from experience.”
How, then, does knowledge arise if not universally through experience? The formulation of his goal is simple and accessible. The answer Kant arrives takes up the bulk of Critique of Pure Reason which is almost universally regarded as one of the most complex, abstruse and often impenetrable (even to philosophy majors) major works of philosophy ever written. Kant himself rather immodestly compared the summation of his revolution in philosophy thought found within the difficult language of Critique of Pure Reason to paradigm-shattering moment that Copernicus realized that it was not the stars which were revolving around someone staring up into sky at night, but rather than person looking up who was revolving. Kant’s theories shattered long-established conventions in much the same way that Copernicus shattered long-established astronomical “truths” and nothing afterward was ever the same.