Editing Knowledge by acquaintance (section)

==="On Denoting"===
The distinction in its present form was first proposed by British philosopher [[Bertrand Russell]] in his famous 1905 paper, "[[On Denoting]]".<ref name=Denoting>{{Cite journal | last = Russell  | first = Bertrand  | authorlink = Bertrand Russell   | title = On Denoting  | journal = Mind  | volume = 14  | issue = 56  | pages = 479–493  | publisher = Oxford University Press on behalf of the Mind Association | location = Oxford  | date = October 1905  | doi = 10.1093/mind/XIV.4.479 | jstor = 2248381 | issn = 0026-4423| url = https://zenodo.org/record/1431813 }}</ref> According to Russell, knowledge by acquaintance is obtained exclusively through experience, and results from a direct causal interaction between a person and an object that the person is perceiving. In accordance with Russell's views on perception, [[Sense data|sense-data]] from that object are the only things that people can ever become acquainted with; they can never truly be acquainted with 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 [[Philosophy of perception|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 [[Simple non-inferential passage|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.