Concept that was the focus of dispute between Locke and Berkeley. Locke had highlighted the problem of the way in which a particular idea, as it might be of a person or a cow, comes to stand for just the right class of things: persons or cows in general. His solution was to postulate an abstraction of the general kind away from the particular qualities of examples, until eventually we have an idea of the right degree of generality: one that encompasses all and only persons, or cows. Berkeley took the greatest exception to this account, arguing instead that all ideas are perfectly particular, and only become general in the use we make of them. His animosity arose partly because he believed that the doctrine of abstraction enabled Locke to deceive himself that we can make sense of things that are actually unintelligible: objects with no colour, inanimate causes, and qualities of things dissociated from the sensory effects they have on us.