I had therefore to remove knowledge, in order to make room for belief.

Kant writes this line in the Preface to the second edition (1787) of the Critique of Pure Reason, while explaining the aim of his “critical” philosophy. In the wake of Enlightenment debates between rationalists and empiricists, and amid controversies over metaphysics, God, freedom, and immortality, Kant argues that speculative (theoretical) reason overreaches when it claims knowledge of things beyond possible experience. By delimiting what we can know—restricting knowledge to phenomena structured by our cognitive faculties—he intends to block dogmatic metaphysics and also to undercut skeptical attacks on religion and morality. The “room” made is for rational faith grounded in practical reason rather than theoretical proof.

Kant is not advocating ignorance; he is distinguishing kinds of rational warrant. “Knowledge” here means theoretical cognition that can be justified as objectively valid, which for Kant requires possible experience. Claims about God, the soul, or freedom cannot be known in that sense, because they transcend experience. Yet Kant thinks these ideas are still indispensable: moral agency presupposes freedom, and the moral law rationally authorizes “belief” (Glaube) in God and immortality as postulates of practical reason. The sentence captures his strategy: limit speculative reason to secure a non-dogmatic, non-skeptical basis for moral and religious commitment—belief without pretending to metaphysical proof.

“I have therefore found it necessary to deny knowledge, in order to make room for faith.”