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Locke’s association-of-ideas discussion appeared in the Essay’s 1700 edition.

The Claim

John Locke developed associationist psychology in "An Essay Concerning Human Understanding" (1689), which was later extended by David Hartley in "Observations on Man" (1749).

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The Short Version

The claim significantly overstates Locke's role and contains a factual dating error. Locke's chapter on "association of ideas" was added in the 1700 fourth edition of the Essay, not the 1689 first edition, and authoritative philosophical references explicitly state he did not develop a formal or systematic associationist psychology — he treated association primarily as a source of cognitive error. While Hartley's 1749 work is correctly identified as a landmark in associationist psychology, crediting Locke with "developing" the field misrepresents the historical record.

Caveats

  • Locke's 'association of ideas' chapter was added in the 1700 fourth edition of the Essay, not the 1689 first edition cited in the claim — a factual error.
  • Multiple authoritative sources (Stanford Encyclopedia of Philosophy) explicitly state that Locke did not develop a formal theory of psychological association; systematic associationism is generally credited to later thinkers such as Hume and Hartley.
  • Describing Hartley as merely 'extending' Locke understates Hartley's original contribution in creating the first comprehensive associationist psychology, which drew on multiple predecessors beyond Locke alone.

The Receipts

  1. Observations on Man - Cambridge University Press & Assessment

    Cambridge University Press

  2. John Locke

    Stanford Encyclopedia of Philosophy

  3. Associationism in the Philosophy of Mind

    Internet Encyclopedia of Philosophy

  4. Associationist Theories of Thought

    Stanford Encyclopedia of Philosophy

  5. "Hartley on associations of the mind and vibrations of the body"

    Rice University

  6. John Locke's (1632–1704) Essay Concerning Human Understanding (1689)

    Open Textbooks BC

  7. The History of Associationism and British Medical Psychology

    Cambridge University Press

  8. A new history of Hartley's Observations on Man

    PubMed

  9. Observations on man, his frame, his duty, and his expectations. In two parts. By David Hartley, ... 1749: Volume 2

    Internet Archive

  10. Observations on man:: his frame,his duty,and his expectations (1749)

    Internet Archive

+ 6 more sources — see the full list on Lenz

Filed Under

An Essay Concerning Human UnderstandingAssociationismDavid HartleyJohn LockeObservations on Man

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