Knowledge by acquaintance

Bertrand Russell makes a distinction between two different kinds of knowledge: knowledge by acquaintance and knowledge by description. Whereas knowledge by description is something like ordinary propositional knowledge (e.g. "I know that snow is white"), knowledge by acquaintance is familiarity with a person, place, or thing, typically obtained through perceptual experience (e.g. "I know Sam", "I know the city of Bogotá", or "I know Russell's Problems of Philosophy"). According to Bertrand Russell's classic account of acquaintance knowledge, acquaintance is a direct causal interaction between a person and some object that the person is perceiving.