DE Weekly: Kant, Kantianism, & Transcendental Idealism
Below is an archived email originally sent on January 26, 2026.
Kant, Kantianism, & Transcendental Idealism
Existentialism came into its own as a bona fide philosophical discipline in the twentieth century but, as I’ve written in the past, it traces its roots to centuries before it was coined. I believe one such “root” is German philosopher Immanuel Kant, an eighteenth-century Aufklärung (Enlightenment) thinker whose moral ethics have had a major impact on Western philosophy.
Kant’s ethical framework has had such a major impact, in fact, that it’s often referred to as Kantianism.
Among his famous questions are, "What can I know?", "What must I do?", and "What may I hope?" These questions (which are inherently existential, I might add) sought to explore the moral duties of the Self, that is, they implored us to turn to our human reason to discover a universal moral law to abide by.
Like other Enlightenment thinkers, Kant believed that human reason was the highest basis for morality, faith, and freedom. He believed that our ability to reason is what distinguished us from other animals, giving us each a shared common dignity and due respect.
For Kant, the way we treat humanity in ourselves and in others is not just the means (read: our day-to-day actions), but an end in itself.
In other words, our highest moral duty is to treat others how we want to be treated––the “Golden Rule,” as it were.
Key to Kant’s philosophy is what is known as the Kantian “categorical imperative,” a deontological theory which posits that we have a human duty to act morally, and that our actions are only moral if they can be universalized.
Before acting, Kant would argue, we must ask ourselves whether our actions could be rationally applied to everyone, without contradiction. This is because, as humans, we all share a common intrinsic worth and each Self is an end in itself.
Kant is an Enlightenment philosopher––a German high-Auflkarüng philosopher––through and through. His philosophy embodies totally the Enlightenment virtues of duty, morality, and good will.
But what sets Kant apart from his contemporaries is the hint of early Existential thought in his writings.
Here’s why I say that.
Kant employed the concepts of phenomena and noumena in his writings; phenomena referring to the world as we perceive and experience it, noumena to the world as it is in itself.
Phenomena is what is filtered in our minds, and noumena is what things truly are: the things-in-themselves.
These two terms are crucial in understanding Kant’s Transcendental idealism. Through the lens of transcendental idealism, humans can only know the world as it appears to them (that’s the phenomena half), not as the true external reality that really exists (that’s the noumena half).
What does this have to do with Kant’s idea of universal morality? Well, it means that, try as we might, we never really grasp “things-in-themselves”; instead, we perceive things subjectively, categorized by our unique cognitive faculties.
This implies that while what we strive for is a concrete understanding of what is morally upright in a universal sense, it’s always just beyond our grasp. That’s why it is so difficult to know and to judge what is universally morally correct according to our human duty and universal “rules.”
Knowledge of the world appears to us, but it is fleeting; we are forever separated from the ultimate nature of the world. This is how Kantian idealism transcends us.
It is in this manner, then, that Kant’s ideas are a precursor to existentialism.
Akin to popular twentieth-century existentialist thought, Kant also believed that we have an inescapable level of freedom as humans that imbues us with the personal responsibility to act in Good Faith toward the Other.
Inherent to Kant’s philosophy, just as in existentialism, is the idea that we are tasked with acting authentically thanks to said freedom.
We all bear a burden of responsibility demanding us to make the “right” choices––choices that create meaning, create value for the Other, and fulfill a higher purpose outside of the Self.
The major difference between the two philosophies is that existentialists believe we must create such conditions ourselves, while Kant believes such conditions already exist, if only we could attain them.
As I hope I’ve illuminated, Kant was one of those thinkers whose ideas laid the groundwork for centuries of philosophical thought to follow.
His ideas are relevant when discussing idealism, transcendentalism, universalism, utilitarianism, and yes, existentialism.
We are left asking ourselves, “How do I use my reason to align with the universal moral law?” And what is that, exactly?
“Two things fill the mind with ever-increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them: the starry heavens above me and the moral law within me.” –– Immanuel Kant, Critique of Practical Reason
Thanks for reading.
Sincerely,
Brandon J. Seltenrich
P.S.––
Another newsletter, another new philosopher. I can’t believe I haven’t written about Kant before. Hope you liked this one.
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