I · Precursors — Empiricism
John Locke
1632 – 1704
Empiricist
The mind is a blank slate — all knowledge comes from sensory experience. No innate ideas.
Key idea
"Tabula rasa"
David Hume
1711 – 1776
Empiricist
Causality is just habit of mind — we never observe necessity, only sequence. Woke Kant from his "dogmatic slumber."
Key idea
Skepticism about causation
↓
Kant's response to Hume's challenge
II · The Pivot — Critical Philosophy
Immanuel Kant
Central node
1724 – 1804
Critical Idealist
Synthesised rationalism and empiricism. The mind doesn't mirror reality — it structures it. We can only know phenomena, never the thing-in-itself. Morality must be grounded in pure reason alone.
Key ideas
Phenomena / Noumena · Categorical Imperative · Synthetic a priori
↓
Three diverging branches from Kant
III · Direct Successors — German Idealism
J.G. Fichte
1762 – 1814
Idealist — extends Kant
Removes Kant's "thing-in-itself." The self (Ich) posits both itself and the world entirely.
Twist on Kant
No noumena needed — only the self
G.W.F. Hegel
1770 – 1831
Idealist — radicalises Kant
Reality itself is Mind (Geist) unfolding historically through contradiction and synthesis. History has a direction.
Twist on Kant
Static categories → dynamic dialectic
Schopenhauer
1788 – 1860
Idealist — darkens Kant
Accepts the phenomena/noumena split but claims the thing-in-itself is blind, irrational Will. Deeply pessimistic.
Twist on Kant
The noumenon is Will, and it is suffering
IV · Second Wave — Reactions & Radicalisation
Karl Marx
1818 – 1883
Hegel → Material
Inherits Hegel's dialectic but grounds it in material conditions, not Spirit. History is driven by class struggle.
Twist on Hegel
"Turned Hegel on his head"
Nietzsche
1844 – 1900
Schopenhauer → Critique
Inherits Schopenhauer's Will but rejects his pessimism and attacks Kant's moral law as disguised Christianity.
Twist on Kant
Morality as power, not duty
V · 20th Century — Phenomenology & Political Philosophy
Edmund Husserl
1859 – 1938
Kant → Phenomenology
Radicalises Kant's focus on how consciousness structures experience. Wants to describe that structuring rigorously.
Key idea
Intentionality of consciousness
Heidegger
1889 – 1976
Husserl → Being
Confronts the Kantian subject head-on. Asks not "how do we know?" but "what does it mean to be?"
Twist
Epistemology → ontology
John Rawls
1921 – 2002
Kant → Political Ethics
Builds political philosophy on Kantian foundations. Rational agents behind a "veil of ignorance" choose fair principles.
Key idea
Justice as fairness