Emmanuel Kant
Set the limits of reason; act from duty.
Emmanuel Kant (1724 – 1804, Prussia) : critical philosophy (transcendental idealism) and kantian ethics. Before knowing the world, we must examine what reason can know. Kant reverses the perspective: objects conform to our cognition. On AskPhilosophy: 16 reconstructed arguments, 4 quotes checked word for word against the original texts, and 2 common beliefs examined; every text carries an authenticity badge (written by the author, posthumous, student notes, reported, apocryphal).
Why he matters
His "Copernican revolution" reshaped the theory of knowledge. His ethics of duty and human dignity still inspires human rights. He closed the door on classical proofs of God while keeping faith as a moral "postulate".
His times
He hardly ever left Königsberg. A university professor, he published his major work at 57, after ten years of silence. He championed the Enlightenment: "Have courage to use your own understanding."
His positions
click a row to see the evidenceTheoretical reason cannot prove God, but practical reason posits him as a "postulate": a belief required by moral life, not knowledge.
Neither rationalist nor empiricist: all knowledge begins with experience, but our mind's forms organise it. Objects conform to our cognition.
Certainty is possible within the limits of experience (mathematics, physics); impossible beyond them (God, the soul, the world as a whole).
We cannot prove the soul is an immaterial substance, nor the opposite: the question exceeds possible knowledge.
Freedom is the condition of the moral law, and the moral law is how we know we are free.
The moral law is universal and binds every rational being, regardless of desires and cultures.
He limits knowledge to make room for faith: reason sets its own limits, beyond which a rational faith remains possible.
The meaning of human life is moral: becoming worthy of happiness through duty. Hence his awe at "the moral law within".
Humans are capable of reason and morality, yet readily remain in a self-incurred "immaturity".
Defends the free, public use of reason as the condition of Enlightenment, while advocating obedience to the law.
The ethics of duty par excellence: an action is right if its maxim can become a universal law, whatever the consequences.