Abstract

LOCKE famously defines knowledge as “the perception of the connexion and agreement, or disagreement and repugnancy of any of our Ideas” (Essay IV i 2), but his subsequent discussion significantly extends this somewhat vague and unclear definition. He starts by suggesting that knowledge always concerns one of four types of agreement or disagreement, namely “Identity, or Diversity”, “Relation”, “Co-existence, or necessary connexion”, and “real Existence”--his examples of the first two of these (perceiving the self-identity and distinctness of ideas, and the relations between ideas) fit relatively comfortably with his definition, but knowledge of “co-existence” (Locke instances the fixedness of gold and the magnetisability of iron) and “real existence” (for example of physical objects, or of God) both seem to involve the “agreement” of ideas with external things rather than merely amongst themselves.