In a few short paragraphs of The Problems of Philosophy Bertrand Russell presents his theory of introspective knowledge based on the concept of knowledge by acquaintance. In this article, I critically analyze these comments by Russell and their proposed application by contemporary authors, including Brie Gertler (2001; 2011) and Laurence BonJour (2003). I show how these theories differ from the competing ‘inner‑sense theories’ and try to show that they are inconsistent with Gareth Evans’s ‘transparency’ observation. Then I compare acquaintance theories with Alex Byrne’s (2005; 2012) ‘transparency’ theory and show that Byrne’s theory offers a simpler account of mechanisms governing introspection and attribution of mental states to other agents than the observer.

The article analyzes Bertrand Russell’s distinction between knowledge by acquaintance and knowledge by description contained in his writings from 1910 to 1912. I point to some problems that arise from Russell’s concept of direct knowledge if they are observed in the light of modern psychological and neuroscientific research. In some cases knowledge by acquaintance may be mediated by certain unconscious operations and by mental representations of conceptual nature. I point out however that some of the examples given in The Problems of Philosophy can be characterized by a different degree of indirectness. Consequently, I propose to view Russell’s distinction as a typology. Because Russell narrows knowledge by description to specific descriptions, Russell’s division is not exhaustive and therefore is not a logical one. The article also shows that there are reasons for both narrowing his category of direct knowledge (e.g. by excluding universals) and for expanding it (e.g. by unconscious experiences).

The article addresses the problem of properties and epistemic functions of Russellian ‘knowledge by acquaintance’ interpreted here as a variant of intuition. The epistemic functions of intuition can be performed in two ways: first, as propositional knowledge of direct and immediate kind (a foundational function), and secondly, as a non-‑propositional form of consciousness that provides a justifying basis for intuitive truths. The distinction between these two functions of intuition presupposes a differentiation – not explicitly articulated by Bertrand Russell – between acquaintance and knowledge by acquaintance. Acquaintance as a form of non‑propositional consciousness is not epistemically autonomous, which is to say that it is not a judgment and cannot be qualified as either true or false, so a separate epistemic problem arises here, one of the shift from acquaintance to knowledge by acquaintance. The author points out that the shift from acquaintance to knowledge by acquaintance is difficult to accomplish, and she offers the opinion that the epistemic function of acquaintance or, more generally, of various similar kinds of consciousness, should not be interpreted in terms of justification. They should be understood not as a justifying element or a justifying reason for propositions that underlie other propositions, but as a factor that is an indispensable genetic and simultaneously structural element of propositional content in the sense assumed in transcendental philosophy.