Different ways of thinking, one search for understanding
Metaphysics — What is reality?
Is the world made of change, or is it eternal and unchanging?
- (c. 535–475 BCE) Heraclitus — Everything flows. Reality is constant change.
- (c. 515–450 BCE) Parmenides — Only Being is. Change is illusion. Reality is one and eternal.
This first clash becomes the root of metaphysics.
Every later philosopher must choose: change or permanence?
- (428–348 BCE) Plato — Reality lies beyond what we see, in timeless Ideas.
- (384–322 BCE) Aristotle — Reality is substance: things with purpose, cause, and form.
- (1225–1274) Thomas Aquinas — Being comes from God, the source of existence.
- (1632–1677) Baruch Spinoza — There is only one substance: God or Nature.
- (1724–1804) Immanuel Kant — Mind shapes reality; we never know the world “as it is.”
- (1889–1976) Martin Heidegger — The question of Being is our deepest human concern.
Metaphysics
Virtue Ethics — How Should We Live?
The good life depends on the character we build.
- (470–399 BCE) Socrates — To live well, we must question ourselves.
- (428–348 BCE) Plato — Virtue is harmony within the soul.
- (384–322 BCE) Aristotle — Virtue lies in the balance between extremes — the “golden mean.”
Virtue Ethics
Rationalism — The Truth Through Reason.
Knowledge begins in the mind, not in the senses.
- (1596–1650) René Descartes — I think, therefore I am. Certainty comes from thinking.
- (1632–1677) Baruch Spinoza — Reality has a logical structure, like geometry.
- (1646–1716) G. W. Leibniz — The universe is made of rational units called “monads.”
Rationalism
Empiricism — The Truth Through Experience
We know the world through our senses.
- (1632–1704) John Locke — The mind starts as a blank slate.
- (1685–1753) George Berkeley — To be is to be perceived.
- (1711–1776) David Hume — We cannot be certain of cause, or even of ourselves.
Empiricism
Existentialism — Meaning Through Freedom
Life has no meaning until we choose one
- (1813–1855) Søren Kierkegaard — Truth is personal; faith is a leap.
- (1844–1900) Friedrich Nietzsche — We must create our own values. Meaning is our task.
- (1905–1980) Jean-Paul Sartre — Existence comes first — we decide who we become.
- (1908–1986) Simone de Beauvoir — Freedom demands responsibility — especially toward others.
Existentialism
Utilitarianism — The Ethics of Happiness
The right action is the one that brings the greatest good.
- (1748–1832) Jeremy Bentham — Morality is a calculation of pleasure and pain.
- (1806–1873) John Stuart Mill — Quality of happiness matters more than quantity.
- (1838–1900) Henry Sidgwick — Rational analysis of which actions truly maximize happiness.