Kant’s “Critique of Pure Reason”: A Short and Incomplete Summary, and a Statement about Why It’s Still Important
Kant’s best-known work, The Critique of Pure Reason (first edition 1781, second 1787) was revolutionary in several respects. It shifted philosophy’s focus from immediate observation of the world to the human mind itself — how it functions at its most basic level and how it interacts with the world to create experience. In prose so mathematically precise it could have been written by a computer, Kant attempts to establish the process by which we come to know anything, in addition to the limits to our knowledge.
We can’t be certain, he argues, about anything which lies beyond our experience, and thus we can never know God, much less prove God’s existence. For him this doesn’t mean that faith is impossible, but rather that it can’t be grounded in reason, which is what most philosophers in previous centuries had tried to demonstrate. In distinguishing between the knowable and unknowable, Kant ultimately seeks to lay the groundwork for a solid-as-possible system of morals.
Refreshingly opposed to arguments for religious belief based in dogma — those forwarded, for example, by the Scholastics, whose main principles couldn’t be proved — Kant also rejects David Hume’s skeptical thesis that direct observation (a posteriori knowledge) is the only grounds for truth. Kant proposes a middle ground between Hume’s thought and the rationalist case that truth can be reached through reasoning alone (a priori knowledge).
This mediating ground Kant terms synthetic a priori reasoning: a priori because we have certain structures and tools built into our minds that help us make sense of our experience. The most important tool is our inherent understanding of how space and time work. For Kant, we don’t know what space and time are because of experience. Our knowledge of them is embedded in our minds, much like the capacity for language is in Chomsky’s universal grammar. It’s through space and time that we come to learn new information, which is where the synthetic part comes in. Through them, we discover, say, how gravity works, or that sometimes it rains, or that there are people who, because they have no lives, laugh-react to Facebook stories about migrants drowning in Europe.
Our knowledge, Kant suggests, begins with intuition (immediate sense perception, like sight and smell). This information is then formed, by our understanding, into concepts, and then our reasoning capacity organizes these concepts into categories like color, quantity, possibility, wholeness, and cause-effect relationships. We classify, for example, objects based on their whiteness: snow, clouds, milk, rice, and Pat Sajak. We also group things together in terms of number: a dozen eggs, a married couple, a band of brothers. (A pair of scissors is different in this regard, less because of logic than of language.) When we organize things in such ways, knowledge is created and systematized. Disciplines begin to develop. Truths are established and more questions are asked and then answered.
Up to a point, anyway. In his determined, often excruciating style of thinking and writing, Kant stresses that there’s only so much we can know about the world. We may be programmed, so to speak, to ask all kinds of questions, including those about God (which he calls metaphysical). But so long as we’re living in our bodies, we’ll never know with complete certainty the answers to some questions. Our ability to reason, though powerful, isn’t equipped to learn everything. We only have access to phenomena, or things as they appear to us, and never to noumena, or things as they are in themselves. It’s into the latter category that the nature of the universe and God would fall, as well as the existence of heaven or hell and whether we’ll be rewarded or punished for our actions in an afterlife.
But for Kant this doesn’t mean we can’t act as if God exists. We may be better off, he believes à la Pascal’s wager, if we did. Belief can guide our behavior in ways reason alone can’t. (It’s into this gray area, it seems, that Kierkegaard plunged and spent his whole writing life.) Ever faithful to his principles, Kant describes the only way he sees belief possible in the Preface to the Second Edition:
I cannot even make the assumption — as the practical interests of morality require — of God, freedom, and immortality, if I do not deprive speculative reason of its pretensions to transcendent insight. … I must, therefore, abolish knowledge, to make room for belief. (xix in my version)
This may sound ominously reminiscent of certain believers in our own time who (to give just one example) prioritize blind faith over knowledge of how vaccines work. But that’s not how I’m reading Kant. He was nothing if not rigorous, thoughtful, and devoted to the discovery of truth. He sticks to his method and his principles throughout The Critique of Pure Reason (and in his later work, where he seeks to develop more fully his moral system). His writing, translated from German (and, in my version, riddled with typos) might be the most challenging I’ve ever encountered. As a whole — and in its parts — it demonstrates a committed engagement with some of the most difficult questions we’ve faced as a species. Near the end of the book, Kant writes about how not just “language in the presence of wonders so inconceivable has lost its force” but also about how “even thought fails to conceive [these wonders] adequately” (223). He was trying his best to write about these deep, unanswerable questions as clearly and honestly as he could.
This is why Kant’s work remains important. These days, we desperately need more sincere and thoughtful engagement with questions about knowledge and morality. Blind faith — in whatever it may be, religious or secular — fosters ideologies that, when left unquestioned and paired with power, produce cruelty and indifference. A better approach would be to begin with the admission that there are some things we don’t know and never will — and then to stop pretending like it’s otherwise, like whole world must submit to our loud and presumptuous ignorance.
