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c. 515–450 BCE · Ancient GreekParmenides
Reason against the senses — thinking shows that change, which we see everywhere, is impossible.
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c. 428–348 BCE · Ancient GreekPlato
The senses give opinion about shadows; true knowledge is of the eternal Forms, reached by reason — the Cave.
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384–322 BCE · Ancient GreekAristotle
Knowledge begins in perception; form is in things, abstracted by the mind.
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1596 – 1650 · FrenchRené Descartes
Doubt everything; the cogito survives; rebuild knowledge on clear and distinct ideas guaranteed by God.
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1632 – 1704 · British & IrishJohn Locke
No innate ideas — all knowledge comes from experience.
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1711 – 1776 · British & IrishDavid Hume
Follow experience all the way — causation is habit, induction unjustified, the self a bundle.
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1724 – 1804 · German-languageImmanuel Kant
The mind supplies the forms of all experience. We know appearances with necessity — but never things in themselves.
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1770 – 1831 · German-languageGeorg Wilhelm Friedrich Hegel
Drop the thing-in-itself. Reason is not trapped behind appearances — truth is the whole, the self-knowing of Spirit.
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1844 – 1900 · German-languageFriedrich Nietzsche
There are no facts, only interpretations. The will to truth itself must be questioned.
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Meanwhile in India, a parallel relay: the Upanishads seek the knowledge that liberates; the Buddhists deny a knower behind knowing; the Nyāya logicians build a theory of valid means of knowledge (pramāṇa) — perception, inference, comparison, testimony; Nāgārjuna turns the pramāṇas against themselves; and Ādi Śaṅkara makes knowledge (jñāna) the only path to liberation.
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Can reason know everything — or are there things the mind can never reach? From the Upanishads’ unknowable knower to Kant’s boundary and Wittgenstein’s silence.
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The great quarrel of early modern philosophy — does knowledge come from reason or from experience? Kant tried to end it.
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Flux and permanence, the moving image of eternity, Augustine’s puzzle, Kant’s form of intuition, eternal recurrence, Heidegger’s temporality.
Being vs. Becoming
The first great quarrel in Western philosophy — is reality one and changeless (Parmenides) or everlasting flux (Heraclitus)?
British Empiricism
The view that all knowledge comes from experience — the mind begins as a blank slate on which the senses write.