The attack on innate ideas
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Before Locke can build his theory of the mind, he first has to clear the ground — and standing in his way is one of the rationalists’ proudest possessions: the idea that we’re born already knowing things.
The rationalists (Descartes, Leibniz) held that the mind comes furnished with certain innate ideas and principles — truths stamped on us at birth, prior to any experience. John Locke opens his Essay Concerning Human Understanding (1690) by devoting the entire first Book to demolishing this doctrine. Only once innatism is cleared away can he build his positive story: that everything in the mind arrives through experience.
Argument 1: The appeal to universal consent fails. The innatist’s favourite evidence is that certain principles — for example Whatever is, is, or It is impossible for the same thing to be and not to be — command universal assent; everyone agrees, so (they claim) the agreement must have been born in us. Locke attacks the premise itself: there simply are no principles that literally all human beings assent to.
Who fails to assent? Children and idiots — infants and the mentally impaired plainly have no grasp of the law of non-contradiction, yet they have minds. And whole peoples, the uninstructed and unlettered, get through life without ever framing these abstract maxims. A truth that a large part of humanity has never so much as entertained cannot have been engraved on every soul at birth (Essay I.ii).
Argument 2: Even universal consent wouldn’t prove innateness. Suppose Locke granted, for the sake of argument, that everyone did eventually agree on some principle. That still wouldn’t show the principle was inborn — because there is an obvious rival explanation: they could all have learned it. If a truth can be acquired through experience and reason, then agreement about it is fully explained without any appeal to innate stamping. Universal consent, even if real, is not a proof; it is at best a fact still in need of an explanation.
Why does Locke say the appeal to universal consent fails to establish innate principles, even setting aside whether consent is truly universal?
Argument 3: Nothing can be ‘in the mind’ that the mind was never conscious of. The innatist has a fallback: perhaps the principles are in the mind implicitly — present but not yet noticed. Locke finds this incoherent. To say a proposition is in the understanding but has never been perceived or known is, he insists, to make “in the mind” mean nothing at all. An idea is a mental item; to have one just is to be conscious of it. A truth “in the understanding” that no one has ever been aware of is an empty phrase.
The positive thesis: the tabula rasa. With innatism cleared away, Locke states his alternative in one of philosophy’s most famous images. The mind at birth is white paper — tabula rasa (a scraped, blank tablet) — “void of all characters, without any ideas.” Whence, then, comes its vast furniture of thought? To this he answers “in one word, from EXPERIENCE” (Essay II.i.2). All the materials of reason and knowledge are supplied by experience; nothing is written on the tablet in advance.
Which best captures Locke's tabula rasa doctrine?