Arthur Schopenhauer began his philosophical path deeply influenced by Immanuel Kant. He revered Kant as a thinker who had “eclipsed all others” and laid the foundations for modern metaphysics. But while Kant provided the intellectual architecture of Schopenhauer’s thought, Schopenhauer ultimately rejected key aspects of Kant’s system. Their relationship is one of inheritance, transformation, and rupture.

Kant’s transcendental idealism

Kant’s system, known as transcendental idealism, claimed that our experience of the world is shaped by the structures of our own mind. Space, time, and causality are not properties of things in themselves; they are the forms through which we perceive phenomena. What we experience is not the world as it is in itself—the noumenon—but the world as it appears to us: the phenomenon.

Reason, for Kant, plays a decisive role in limiting knowledge. He argued that we can never know the noumenon, only the appearances filtered through the categories of human understanding. This epistemological modesty marked a turning point in modern philosophy.

Schopenhauer accepted this central distinction between appearance and reality. But unlike Kant, he did not treat the noumenon as unknowable. Instead, he claimed that we could access the thing-in-itself—not through the intellect, but through inner experience.

The Will

Validating Kant, Schopenhauer proposed that while the external world appears to us as representation—a product of the mind’s structuring activity—we encounter something very different when we examine our own being. However, he felt that behind our actions, behind thought and reason, lies a blind, ceaseless impulse that drives us forward. This is not the individual will as choice or intention. It is the Will: an undivided, universal, irrational force that underlies all reality – an idea that was not aligned with Kant’s philosophy.

The Will is not a property of the human mind—it is the essence of the world itself. It is what Kant called the thing-in-itself. For Schopenhauer, everything in nature—gravity, electricity, animal instinct, human striving—expresses the Will. It is a metaphysical energy, endlessly striving without aim, logic, or rest. This Will does not will something; it simply wills. It is an ontological force, pre-rational and inexhaustible.

Human desire is just one of its many expressions. What we experience as craving, ambition, fear, or pleasure are particular eruptions of this deeper, cosmic striving. Life is filled with suffering because the Will is never satisfied; it keeps pushing, blindly, without end. This redefinition of reality as Will is where Schopenhauer moves far beyond Kant—and opens a darker, more tragic vision of existence.

Ethics

Schopenhauer sharply rejected Kant’s moral philosophy. Kant built his ethics on deontology—the principle that morality is based on duty and adherence to universal moral laws, not on consequences. The cornerstone of Kant’s deontological ethics is the categorical imperative, which states: “Act only according to that maxim whereby you can at the same time will that it should become a universal law.” In other words, one should act only on principles that could apply to everyone, regardless of personal gain or context.

Schopenhauer dismissed this rationalist framework as cold and disconnected from lived experience. He argued that we do not act morally because of abstract, universal rules. We act morally when we feel the suffering of others as if it were our own. True ethics, for him, springs from compassion—an immediate, intuitive recognition that all beings share the same inner essence, the same Will. From this shared essence comes the only possible foundation for moral behavior.

This means Schopenhauer rejected both deontology and consequentialism (the idea that morality is defined by outcomes). He did not believe we should act out of obedience to duty, nor calculate the best consequences. Instead, ethical action arises when we see through the illusion of separateness and identify with the other’s suffering. In this view, harming another being is ultimately harming oneself—because all are expressions of the same underlying Will.

Aesthetic escape from the Will

There is, however, one reprieve. Schopenhauer believed that in rare moments—especially through the contemplation of art—we can detach from the Will. Aesthetic experience suspends our personal desires and lets us see the world not in terms of use or craving, but in pure perception. Music, in particular, expresses the Will directly, bypassing concepts and reaching into the metaphysical core. In such moments, we become for a time free from suffering, because we are no longer driven by the Will.

This aesthetic detachment offers not a permanent solution but a momentary liberation—one of the few windows into a world not dominated by relentless striving.

The metaphysical pessimist

Schopenhauer praised Kant for revolutionizing philosophy, but he saw Kant’s refusal to name the thing-in-itself as an evasion. Where Kant saw limits, Schopenhauer claimed knowledge. And what he found behind appearances was not reason, order, or divine logos—but a turbulent, irrational force at the heart of being.

In the final reckoning, Kant built a system of reason and moral autonomy. Schopenhauer revealed a metaphysics of suffering, driven by a blind, eternal Will. The student revered the master, but he dismantled his legacy and constructed a far more unsettling vision in its place.