In epistemology — the philosophical study of knowledge, its nature, origin, and scope — a crucial distinction was introduced in the early 20th century by Bertrand Russell, a prominent British philosopher. This distinction is between:

• Knowledge by Acquaintance

• Knowledge by Description

This distinction plays a foundational role in understanding how we come to know things, how language refers to the world, and how epistemic justification is grounded.

Bertrand Russell’s Contribution

The distinction between acquaintance and description was articulated most clearly in Bertrand Russell’s essay “On Denoting” (1905) and later in “The Problems of Philosophy” (1912). Russell’s goal was to explain how we can meaningfully speak about objects, especially those we are not directly experiencing, and to analyze the structure of propositions and reference in language and thought.

This distinction is part of a broader theory of meaning, reference, and epistemic access.

Knowledge by Acquaintance

Definition

Knowledge by acquaintance refers to direct, immediate knowledge of objects or experiences. It does not require inference, description, or mediation. It is a non-propositional, non-inferential form of knowledge.

Examples

• Sense-data: When you see a red patch or feel a pain, you are directly acquainted with that sensation.

• Inner experience: You are acquainted with your own thoughts, desires, or emotions.

• Memory and introspection: You are acquainted with your own mental states via introspection.

• Self: According to Russell, one has direct acquaintance with one’s self or subject of consciousness.

Grote

• In 1865, philosopher John Grote distinguished between “knowledge of acquaintance” and “knowledge-about”.

• Grote noted that similar distinctions exist in many languages:

  • Greek: γνωναι (knowledge of acquaintance) and ειδεναι (knowledge-about)

  • Latin: noscere and scire

  • German: kennen and wissen

  • French: connaître and savoir

• Grote’s term “knowledge of acquaintance” is better known today as “knowledge by acquaintance”, following Bertrand Russell’s change of preposition in a 1911 paper presented to the Aristotelian Society.

Helmholtz

• In 1868, Hermann von Helmholtz distinguished between das Kennen and das Wissen.

• Das Kennen refers to knowledge that is “mere familiarity with phenomena”.

• Das Wissen refers to knowledge of phenomena that “can be communicated by speech”.

• Helmholtz stressed that das Kennen could not “compete with” das Wissen despite potentially having “the highest possible degree of precision and certainty”.

• He argued that das Kennen cannot be expressed in words, not even to ourselves.

James

• In 1890, William James agreed with the idea of two fundamental kinds of knowledge, adopting Grote’s terminology.

• He elaborated on the distinction between knowledge by acquaintance and knowledge about.

• James stated that one can be acquainted with many people and things but know very little about their inner nature.

• Examples include knowing the color blue, the flavor of a pear, an inch, a second of time, an effort of attention, or noticing differences between things.

• However, one cannot describe or impart acquaintance to someone who hasn’t experienced it themselves.

• It is impossible to explain sensations or direct experiences fully, e.g., making a blind person understand what blue is like, or defining abstract concepts like a syllogism.

• At best, one can direct others to places or actions where they might gain acquaintance themselves.