An Essay Concerning Human Understanding

John Locke’s 1689 philosophical work argues that ideas originate in experience and examines the nature, extent, and limits of human knowledge.

Empiricism: The theory that knowledge arises primarily or entirely from sensory experience. Locke’s account makes experience the source of all ideas.
Complex idea: An idea formed by the mind from simpler ideas through combining, comparing, or abstracting. Locke explains complex thought as mental work upon experiential materials.
John Locke: An English philosopher whose works helped shape empiricism and political liberalism. Locke developed the Essay’s account of experience, ideas, and knowledge.
George Berkeley: An Irish philosopher who argued that sensible objects exist as perceived ideas and spirits. Berkeley developed an idealist philosophy from questions about perception and ideas raised by Locke.
Personal identity: The question of what makes a person the same individual across time. Locke ties personal identity to continuity of consciousness rather than sameness of substance.
Sensation: The reception of ideas through the external senses. Locke identifies sensation as one of the two sources of ideas.
Abstraction: The mental process of attending to shared features while setting aside particular details. Locke treats abstraction as the source of general ideas and terms.
Innate ideas: Ideas or principles held to be present in the mind independently of experience. Locke’s opening book argues against this rival account of the mind’s contents.
David Hume: A Scottish philosopher whose empiricism analyzed ideas, causation, and the limits of knowledge. Hume extended the empiricist project while drawing more skeptical conclusions.
Memory: The mental capacity to retain or recover information from past experience. Locke’s account makes remembered consciousness central to personal identity.

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