What can I know?
Kant calls the first question “merely speculative”: it does not ask what I ought to do, but how far my knowledge reaches.
In the “Critique of Pure Reason” (1781, second edition 1787) Kant gathers “all the interest” of reason into three questions, and the first is: “What can I know?” His answer stands between two camps of his time. Against the rationalists he insists that there is no knowledge without sensible intuition. Against the empiricists he insists that perception stays unordered without the concepts of the understanding: “Thoughts without content are empty, intuitions without concepts are blind.”
The price of this answer: we know things only as they appear to us, never as they are in themselves. God, freedom and immortality can therefore be neither proved nor disproved. Kant writes: “I had to deny knowledge in order to make room for faith.” Precisely this limit opens the door to the next questions.
Sources: Kant, Critique of Pure Reason, Ak. 3:522 f. (three questions, “merely speculative”; our translation) · Ak. 3:75 (B 75; standard rendering, cf. Guyer/Wood) · Ak. 3:19 (B XXX; standard rendering, cf. Kemp Smith, Guyer/Wood) — Kant corpus (German) · Wikipedia: Critique of Pure Reason
Which chapters and devices stand behind which door is a division for learning, not Kant's own: many of his ideas belong to several questions.
Chapters and works behind this door
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Every device asks you a question first. Reach the insight behind it and you get a star on your star map.
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Kant's concepts in the grid, easy and hard.
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