This is a series on some influential modern thinkers who influenced the world of unbelief. (For previous entries, see FreudMarx, Machiavelli, and Nietzsche.)

These are notes based on an essay by Peter Kreeft; Kreeft is the author of Socrates Meets Kant: The Father of Philosophy Cross-Examines His Most Influential Modern Child (St. Augustine’s Press, 2012).

Who was Immanuel Kant?

A German philosopher.

When did he live?


How do you pronounce his name?

Kahnt (not like “can’t”).

What is his significance?

Immanuel Kant is one of the greatest philosophers in history.

Kant is really two philosophers:

  • a philosopher concerned with how we know things (epistemology)
  • a philosopher of right and wrong (ethics)

If he had written only on either topic, he would still be the most important and influential of the modern philosophers. The combination of the two makes him especially worthy of study.

What was Kant’s style?

Few philosophers in history have been so unreadable and dry as Immanuel Kant. He was an abstract professor, writing in abstract style about abstract questions.

What was his personality?

He was a good-tempered, sweet, and pious man—so punctual that his neighbors set their clocks by his daily walk.

What was his impact?

Few have had a more devastating impact on human thought. He is the primary source of the idea that truth is subjective. Kant, more than any other thinker, gave impetus to the typically modern turn from the objective to the subjective.

What was the basic intention of his philosophy?

He wanted to restore human dignity amidst a skeptical, world-worshiping science.

What did Kant believe about faith and reason?

He helped bury the medieval synthesis of faith and reason. He described his philosophy as “clearing away the pretensions of reason to make room for faith” (as if faith and reason were enemies and not allies).

Kant thought religion could never be a matter of reason, evidence, or argument, or even a matter of knowledge.

Rather, religion was a matter of feeling, motive, and attitude.

What were the two things that filled Kant with wonder?

“Two things fill me with wonder: the starry sky above and the moral law within.”

  • “The starry sky above” is the physical universe as known by modern science.
  • Everything else (including the moral law) is relegated to subjectivity.

What is the moral law for Kant?

The moral law is not “without” but “within,” not objective but subjective, not a Natural Law of objective rights and wrongs that comes from God but a man-made law by which we decide to bind ourselves. Morality is a matter of subjective intention only. It has no content except the Golden Rule (Kant’s “categorical imperative”).

He argued:

  1. If the moral law came from God rather than from man, then man would not be free (in the sense of being autonomous).
  2. But man must be autonomous.
  3. Therefore, the moral law does not come from God but from man.

Why did Kant believe in the existence of God, free will, and immortality?

Kant thought of himself as a Christian, but he explicitly denied that we could know that God, free will, and immorality really exist.

But we must live as if these three ideas were true: if we believe them we will take morality seriously, and if we don’t we will not.

These beliefs, then, are justified by purely practical reasons, not because they are true. Christianity becomes a “value system” rather than “the truth.”

What did Kant make of the supernatural and miraculous claims of traditional Christianity?

He ignored them or interpreting them as myth. Kant’s strategy was essentially the same as that of Rudolf Bultmann, the father of “demythologizing,” whose theories of criticism reduce biblical claims of eyewitness description of miracles to mere myth, “values,” and “pious interpretations.”

What was Kant’s basic question?

How can we know truth?

How did David Hume’s answer to that question influence Kant?

Early in Kant’s life he accepted the answer of Rationalism:

  • we know truth by the intellect (not the senses)
  • the intellect possesses its own “innate ideas.”

Then Kant read the Empiricist David Hume, who, Kant said, “woke me from my dogmatic slumber.” Like other Empiricists, Hume believed that

  • we know truth only through the senses
  • we have no “innate ideas.”

But Hume’s premises led him to the conclusion of Skepticism (the denial that we can ever know the truth at all with any certainty). Kant saw both the “dogmatism” of Rationalism and the skepticism of Empiricism as unacceptable, and sought a third way.

What did Kant call his “Copernican revolution in philosophy”?

Kant invented a wholly new theory of knowledge, usually called Idealism (the simplest term for it is Subjectivism). It amounts to redefining truth itself as subjective, not objective.

Kant’s “Copernican revolution” redefines truth itself as reality conforming to ideas. “Hitherto it has been assumed that all our knowledge must conform to objects . . . more progress may be made if we assume the contrary hypothesis that the objects of thought must conform to our knowledge.”