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Knowledge by acquaintance

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Knowledge by acquaintance

The distinction between "knowledge by acquaintance" and "knowledge by description"[1] was promoted by Bertrand Russell (notably in his 1905 paper On Denoting). Russell was extremely critical of the equivocal nature of the word know, and believed that the equivocation arose from a failure to distinguish between the two fundamentally different types of knowledge.


  • Grote 1
  • Helmholtz 2
  • James 3
  • Russell 4
  • Acquaintance hypothesis 5
  • See also 6
  • Notes 7
  • References 8
  • External links 9


In 1865, philosopher John Grote distinguished between what he described as "knowledge of acquaintance" and "knowledge-about". Grote noted that these distinctions were made in many languages. He cited Greek (γνωναι and ειδεναι), Latin (noscere and scire), German (kennen and wissen), and French (connaître and savoir) as examples.

Grote's "knowledge of acquaintance" is far better known today as "knowledge by acquaintance" following Russell's decision to change the preposition in a paper that he read to the Aristotelian Society on 6 March 1911.


In a similar fashion, in 1868 Hermann von Helmholtz clearly distinguished between das Kennen, the knowledge that consisted of "mere familiarity with phenomena", and das Wissen, "the knowledge of [phenomena] which can be communicated by speech". Stressing that the Kennen sort of knowledge could not "compete with" the Wissen sort of knowledge, Helmholtz argued that, despite the fact that it might be of "the highest possible degree of precision and certainty", the Kennen kind of knowledge can not be expressed in words, "even to ourselves".


In 1890, William James, agreeing there were two fundamental kinds of knowledge, and adopting Grote's terminology, further developed the distinctions made by Grote and Helmholtz:

I am acquainted with many people and things, which I know very little about, except their presence in the places where I have met them. I know the color blue when I see it, and the flavour of a pear when I taste it; I know an inch when I move my finger through it; a second of time, when I feel it pass; an effort of attention when I make it; a difference between two things when I notice it; but about the inner nature of these facts or what makes them what they are, I can say nothing at all. I cannot impart acquaintance with them to any one who has not already made it himself I cannot describe them, make a blind man guess what blue is like, define to a child a syllogism, or tell a philosopher in just what respect distance is just what it is, and differs from other forms of relation. At most, I can say to my friends, Go to certain places and act in certain ways, and these objects will probably come. (1890, p.221)


According to Russell, knowledge by acquaintance is obtained through a direct causal (experience-based) interaction between a person and the object that person is perceiving. Sense-data from that object are the only things that people can ever become acquainted with; they can never truly KNOW the physical object itself. A person can also be acquainted with his own sense of self (cogito ergo sum) and his thoughts and ideas. However, other people could not become acquainted with another person's mind, for example. They have no way of directly interacting with it, since a mind is an internal object. They can only perceive that a mind could exist by observing that person's behaviour.

To be fully justified in believing a proposition to be true one must be acquainted, not only with the fact that supposedly makes the proposition true, but with the relation of correspondence that holds between the proposition and the fact. In other words, justified true belief can only occur if I know that a proposition (e.g. "Snow is white") is true in virtue of a fact (e.g. that the frequency of the light reflected off the snow causes the human eye, and by extension, the human mind, to perceive snow to be white). By way of example, John is justified in believing that he is in pain if he is directly and immediately acquainted with his pain. John is fully justified in his belief not if he merely makes an inference regarding his pain ("I must be in pain because my arm is bleeding"), but only if he feels it as an immediate sensation ("My arm hurts!"). This direct contact with the fact and the knowledge that this fact makes a proposition true is what is meant by knowledge by acquaintance.

On the contrary, when one is not directly and immediately acquainted with a fact, such as Julius Caesar's assassination, we speak of knowledge by description. When one is not directly in contact with the fact, but knows it only indirectly by means of a description, one arguably is not entirely justified in holding a proposition true (such as e.g. "Caesar was killed by Brutus").

The acquaintance theorist can argue that one has a noninferentially justified belief "that P" only when one has the thought "that P" and one is acquainted with both the fact that P is the case, the thought "that P", and the relation of correspondence holding between the thought "that P" and the fact that P is the case. So I must not only know the proposition P, and the fact that P is the case, but also know that the fact that P is the case is what makes proposition P true.

Acquaintance hypothesis

Earl Conee invoked the idea of acquaintance knowledge in response to Frank Jackson's knowledge argument. Conee argued that when Mary the neuroscientist first sees a red object, she doesn't gain new information but rather "a maximally direct cognitive relation to the experience."[2]

Michael Tye makes similar use of the distinction between acquaintance and factual knowledge in his analysis of the Mary thought experiment.[3]

See also


  1. ^ Lazerowitz (p.403) prefers "direct knowledge" and "indirect knowledge" for "knowledge by acquaintance" and "knowledge by description" respectively. The pursuit of knowledge by acquaintance is always susceptible to what James (1890, pp.196–197) labelled "the psychologist's fallacy": namely, the psychologists' tendency to confuse their analyses of subjective experience with the nature of reality ("the great snare of the psychologist is the confusion of his own standpoint with that of the mental fact about which he is making his report"). Parker (1945b, p.458) holds the strong opinion that the term "knowledge by description" is extremely misleading. He advocated using "knowledge merely by description".
  2. ^ Earl Conee (Jun 1994). "Phenomenal knowledge". Australasian Journal of Philosophy 72 (2): 136–150.  
  3. ^ Michael Tye (2009). Consciousness Revisited: Materialism without Phenomenal Concepts. Cambridge, MA and London, England: MIT Press. 


  • Helmholtz, H.L.F. von (Pye-Smith, P.H. trans.), [1868/1881/1962] "The Recent Progress of the Theory of Vision", pp. 93–185 in Helmholtz, H., Popular Scientific Lectures, Dover Publications, (New York), 1962 [Paper first published in German in 1868. This (1962) volume is a selection of the translations that were first published in English in 1881].
  • James, W., The Principles of Psychology: Volume One, Henry Holt and Company, (New York), 1890.
  • Lazerowitz, M., "Knowledge by Description", The Philosophical Review, Vol.46, No.4, (July 1937), pp. 402–415.
  • Parker, D.H. [1945a], "Knowledge by Acquaintance", The Philosophical Review, Vol.54, No.1, (January 1945), pp. 1–18.
  • Parker, D.H. [1945b], "Knowledge by Description", The Philosophical Review, Vol.54, No.5, (September 1945), pp. 458–488.
  • Russell, B., "Knowledge by Acquaintance and Knowledge by Description", Proceedings of the Aristotelian Society (New Series), Vol.XI, (1910–1911), pp. 108–128. [Read to the Society on 6 March 1911.]

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