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John Locke
1632–1704· Philosopher· Knowledge, logic & science
Well documentedSolid records, texts or physical evidence.
English philosopher and physician whose theories of knowledge from experience and of government by consent shaped modern liberal democracy.
See it on the Philosophy map →The idea
Idea: people have natural rights to life, liberty and property, and government exists to protect them. Reasoning: God made people free and equal; you own your labor, so mixing it with land makes it yours. Government is a trust; if it betrays that trust, the people may replace it. His Essay Concerning Human Understanding (1689) says the mind begins blank. Main objections: his property theory was used to justify taking Native American land, and he invested in the slave-trading Royal African Company.
Why it matters
Jefferson's 'life, liberty and the pursuit of happiness' echoes him, and his ideas on consent, rights and religious toleration became core assumptions of modern democracies.
Legacy and sources
His works and papers survive, many in Oxford's Bodleian Library. Two Treatises of Government appeared anonymously in 1689; he admitted writing it only in a codicil to his will.
Still debated
Whether the Two Treatises was written to justify the 1688 Glorious Revolution or years earlier, around 1680, is debated; Peter Laslett argued for the earlier date.
Connections (7)
▸Natural law (the Stoics and Cicero) grounded the rights theory of John LockeWell documented
The connection
The Stoics and Cicero taught that a law of right reason binds all people, above any ruler's decrees. Through Aquinas, Richard Hooker and Hugo Grotius, the tradition reached Locke, who used natural law to argue that people have rights to life, liberty and property before any government exists, and that governments must respect them.
When and how
Locke's Second Treatise of Government (1689), which leans on Hooker's Laws of Ecclesiastical Polity (1594); Cicero stated the idea in On the Republic around 51 BC.
How we know
Locke quotes Hooker repeatedly in the Second Treatise and frames his whole argument in natural law; his early Essays on the Law of Nature (c. 1663–64) survive.
Debates and open questions
Whether Locke's theory is traditional natural law or a modern, more individualist break with it, as Leo Strauss argued, is debated.
▸John Locke built rights and consent into The social contractWell documented
The connection
Locke's state of nature is not war: people already have natural rights and can reason about them. They form government by consent only to protect those rights more securely. If rulers violate them, the trust is broken and the people may resist and replace the government, a direct challenge to Hobbes's absolute sovereign.
When and how
Second Treatise of Government, published anonymously in London in 1689, just after the Glorious Revolution replaced James II with William and Mary.
How we know
The Second Treatise states it directly, and the Declaration of Independence (1776) repeats its logic of rights, consent and the right to alter or abolish government.
Debates and open questions
Who has actually consented, especially people born later who never agreed, and whether 'tacit consent' by living under a government counts, are long-standing objections.
▸John Locke founded British empiricismWell documented
The connection
Locke's Essay launched the tradition: the mind begins as 'white paper', and every idea comes from experience, either sensation or reflection on our own mental operations. He sorted ideas into simple and complex and asked what we can know through them, setting the agenda Berkeley and Hume pursued.
When and how
An Essay Concerning Human Understanding, London, 1689 (title page 1690), begun after a 1671 discussion among friends stalled on basic questions.
How we know
The Essay went through four editions in Locke's lifetime, and both Berkeley and Hume engage it directly and by name.
Debates and open questions
Bacon and Hobbes were empiricists before him, so calling Locke the 'founder' is a convention; he made it the first systematic theory.
▸John Locke was radicalized by George Berkeley: to be is to be perceivedWell documented
The connection
Locke said we perceive ideas, which are caused by material objects we never directly meet. Berkeley pushed the logic further: if we only ever know ideas, the hidden matter behind them is unknowable and unnecessary. So objects just are collections of ideas in minds, ultimately in God's.
When and how
Berkeley, a young fellow of Trinity College Dublin, published his Principles in 1710 and Three Dialogues in 1713, both responding to Locke's Essay.
How we know
Berkeley's Principles names Locke and attacks his 'abstract ideas' and his split between primary qualities (shape, motion) and secondary ones (color, taste).
Debates and open questions
Whether Berkeley read Locke fairly, and whether idealism really follows from Locke's premises, is debated.
▸John Locke influenced Montesquieu and the separation of powersWell documented
The connection
Locke distinguished legislative, executive and 'federative' (foreign affairs) powers and insisted that lawmaking power be limited. Montesquieu refined this into three branches, adding an independent judiciary, and shared Locke's goal of government that protects liberty, using the English system both men admired as the model.
When and how
Locke's Second Treatise (1689); Montesquieu's The Spirit of the Laws (1748), written after his stay in England, 1729–31.
How we know
Book 11, Chapter 6 of The Spirit of the Laws, on the English constitution, closely parallels Locke; Montesquieu seldom cites him, so the link is inferred.
Debates and open questions
Some historians argue English writers such as Bolingbroke, and Montesquieu's own observations, shaped him as much as Locke did.
▸Robert Nozick, Anarchy, State, and Utopia revived the property-rights theory of John LockeWell documented
The connection
Nozick built on Locke's view that people have natural rights to life, liberty and property, and that you come to own unowned things by mixing your labor with them. He kept a weaker form of Locke's proviso that taking must leave 'enough, and as good' for others, and concluded only a minimal state protecting these rights is justified.
When and how
Anarchy, State, and Utopia (1974) opens with Locke's state of nature and examines his theory of acquisition in chapter 7.
How we know
Nozick cites and analyzes Locke throughout, and probes the puzzles: does pouring your can of tomato juice into the sea make you own the sea?
Debates and open questions
Nozick admitted he lacked a full theory of acquisition; whether Locke's religious premises can support a secular libertarianism is debated.
▸John Locke gave the memory-based answer to What makes you the same person over time?Well documented
The connection
Locke argued that a person is a thinking being that can consider itself the same across time, and that personal identity reaches as far back as consciousness, in effect memory, reaches. His case: if a prince's consciousness entered a cobbler's body, the person would be the prince.
When and how
The chapter 'Of Identity and Diversity' (Essay, Book 2, Chapter 27), added to the second edition in 1694 at William Molyneux's urging.
How we know
The chapter is the standard starting point; Joseph Butler (1736) and Thomas Reid (1785) published influential objections to it.
Debates and open questions
Whether Locke meant memory alone or a broader continuity of consciousness, and how his view handles forgetting, remains debated.