Canonical · Philosophy & the Self · Book

An Essay Concerning Human Understanding

John Locke · 1689

"The mind at birth is a blank slate, tabula rasa, with no innate ideas — all knowledge, without exception, is built up from sensory experience and the mind's reflection on that experience."

The idea

Locke's Essay was a direct attack on the then-dominant rationalist view that some ideas, of God, of logic, of morality, are innate, built into the mind before any experience. His alternative: the mind starts as a blank slate, and every idea, no matter how abstract, can ultimately be traced back to either sensation, direct input from the external world through the senses, or reflection, the mind's own operations on those sensory ideas, like combining, comparing, or abstracting them.

Why it works

He distinguishes simple ideas, which arrive directly from experience and can't be broken down further, like the color red or the taste of sugar, from complex ideas, which the mind constructs by combining, comparing, or abstracting from simple ones — the idea of a unicorn combines the simple ideas of horse and horn; the idea of justice is a complex abstraction built from many observed instances. Since even your most abstract concepts trace back through this chain to raw sensory experience, Locke's test for any claimed piece of knowledge is: what experience is this actually built from, and does the chain back to that experience actually hold?

The takeaway — recall it first

Check your understanding

What is Locke's central claim about the mind at birth?

Meditations on First Philosophy

"By systematically doubting everything that can possibly be doubted, including the reliability of the senses, Descartes arrives at one thing that survives the doubt — the fact that he is thinking, and therefore exists, cogito ergo sum — and builds all further certain knowledge back up from that single indubitable foundation using reason alone."

René Descartes · BookContinue→