William of Ockham
1287 CE – 1347 CE · Medieval Era
“Entities should not be multiplied beyond necessity: the simplest explanation is preferable.”
Biography
William of Ockham was a Franciscan friar whose nominalism and logical rigor challenged the dominant Scholastic tradition. His famous 'razor', the principle of parsimony, became a basic tool of scientific reasoning. He also wrote extensively on political philosophy, defending the separation of church and state.
Major Works
Key Arguments
Click “Philosophy 101” to read the full exploration of each argument.
Ockham's Razor
Plurality must never be posited without necessity. When explaining any phenomenon, prefer the hypothesis that makes the fewest assumptions.
Why it matters: Became one of the basic principles of scientific method and rational inquiry.
Nominalism
Universals, categories like 'redness,' 'justice,' or 'humanity', do not exist as real things in the world. Only individual, particular things exist. When we say two apples are both 'red,' we are using a convenient label, not referring to some abstract entity called Redness that exists independently of the apples. The word 'red' is just a name (nomen) we apply to similar individuals.
Why it matters: A position with far-reaching consequences. By denying the independent reality of universals, Ockham undermined the metaphysical foundations of scholastic philosophy and paved the way for empiricism, modern science, and the analytical tradition. If only individuals are real, then knowledge must begin with observation of particulars, not contemplation of abstract forms.
Separation of Faith and Reason
Ockham argued that God's existence and attributes cannot be proven by philosophical reasoning, they must be accepted on faith alone. Reason operates within the natural world; God's will is absolutely free and not bound by any rational necessity we can discover. This sharply limited what philosophy could claim to know about theological matters.
Why it matters: Broke the synthesis between faith and reason that Aquinas had carefully constructed. By limiting reason's reach, Ockham paradoxically liberated both science (which could now study nature on its own terms) and theology (which no longer needed to conform to Aristotelian philosophy). His position foreshadowed the modern separation of scientific and religious inquiry.
Lasting Influence
His razor principle shaped the scientific revolution. His nominalism influenced empiricism and analytic philosophy.
Your Reading Path
The Companion Guide
Seven eras of philosophy in one volume — reading lists, key terms, journal prompts · $19.99