Epistemologists - Knowledge - Knowledge That, Knowledge How, and Knowledge By Acquaintance

Knowledge That, Knowledge How, and Knowledge By Acquaintance

In epistemology in general, the kind of knowledge usually discussed is propositional knowledge, also known as "knowledge that." This is distinct from "knowledge how" and "acquaintance-knowledge." For example: in mathematics, it is known that 2 + 2 = 4, but there is also knowing how to add two numbers and knowing a person (e.g., oneself), place (e.g., one's hometown), thing (e.g., cars), or activity (e.g., addition). Some philosophers think there is an important distinction between "knowing that," "knowing how," and "acquaintance-knowledge," with epistemology primarily interested in the first.

Bertrand Russell is famous for distinguishing "knowledge by description" (a form of knowledge that) and "knowledge by acquaintance" in Problems of Philosophy. Gilbert Ryle is often credited with emphasizing the distinction between knowing how and knowing that in The Concept of Mind. In Personal Knowledge, Michael Polanyi argues for the epistemological relevance of knowledge how and knowledge that; using the example of the act of balance involved in riding a bicycle, he suggests that the theoretical knowledge of the physics involved in maintaining a state of balance cannot substitute for the practical knowledge of how to ride, and that it is important to understand how both are established and grounded. This position is essentially Ryle's, who argued that a failure to acknowledge the distinction between knowledge that and knowledge how leads to vicious regresses.

In recent times, some epistemologists (Sosa, Greco, Kvanvig, Zagzebski) have argued that epistemology should evaluate people's properties (i.e., intellectual virtues) and not just the properties of propositions or propositional mental attitudes.