Kant and Critical Philosophy

What did Kant criticize

When we call Immanuel Kant’s philosophy “critical philosophy,” “critical” doesn’t simply mean opposing something. Here, critique is the work of examining the limits of what human reason can and cannot do.

In Kant’s time, rationalism and empiricism explained the grounds of knowledge from opposite directions. Rather than picking one side, Kant held that experience supplies the raw material for knowledge, while the forms of the human mind organize that material into order.

The Copernican turn

One of Kant’s famous phrases is the “Copernican turn” in philosophy. Where earlier thinkers assumed that our cognition conforms to objects, Kant held that objects are experienced within the conditions of our own cognition.

Put simply, we don’t copy the world exactly as it is. We experience the world through frameworks like time, space, and cause and effect. So knowing isn’t passive reception — it’s active construction.

Faculty	Description
Sensibility	Receives sensory data within time and space
Understanding	Organizes experience into judgable form through categories
Reason	Pursues greater unity and principles

Appearances and the thing-in-itself

Kant calls the world we experience “appearances.” Appearances are the world as it shows up within the conditions of human cognition. The “thing-in-itself,” by contrast, refers to what an object is regardless of our conditions of cognition — but humans cannot know it directly.

This distinction isn’t nihilism. Kant isn’t saying we know nothing at all — he’s trying to clarify the scope and conditions of what we can know.

Moral philosophy: duty and autonomy

Kant’s ethics places weight on the principle behind an action rather than its results. Just because an action produced a good outcome doesn’t mean it’s automatically moral. He asks whether the action arose from a principle that could be universalized, and whether it treats people as more than mere means.

For example, a lie might produce a convenient outcome in the moment, but a principle that allows lying whenever it’s convenient would undermine trust itself. Kantian ethics examines the principle behind an action in this way.

Putting the categorical imperative in plain language

The categorical imperative refers to a moral law that must be followed unconditionally. It sounds difficult, but in everyday terms it can be rephrased as two questions.

Would it be acceptable if everyone followed the principle behind my action?
Am I treating this person as a mere tool rather than as an end?

Imagine wanting to take credit for a coworker’s achievement. Asking whether it would be fine if everyone acted on that principle, and whether you’re treating your coworker merely as a means to your own benefit, changes the judgment.

Kant’s significance and limits

Significance	Description
Examining the conditions of cognition	Structurally explained how humans experience the world
Universality of morality	Emphasized the importance of principle over mood or outcome
Human dignity	Set the standard of treating people as ends, not means

Still, Kant’s philosophy is also criticized as overly strict. In complex real-world situations, outcomes, relationships, and emotions inevitably affect judgment too. Even so, Kant’s questions remain a powerful standard for keeping ethical judgment from becoming muddled.

Key takeaways

Kant’s critical philosophy examines the powers and limits of human reason.
Kant held that the material of experience and the forms of cognition together construct knowledge.
Appearances are the world we experience, while the thing-in-itself refers to what we cannot directly know.
Kantian ethics values universalizable principles and human dignity over outcomes.
The categorical imperative can be applied day to day by asking “would this be fine for everyone?” and “am I treating people as mere means?”

Next chapter: how Hegel, Marx, and Nietzsche shook up questions of history, society, and value after modernity.