In epistemology, the branch of philosophy concerned with the nature, origin, and limits of knowledge, a significant distinction is drawn between knowledge that (also known as propositional knowledge) and knowledge how (also known as practical knowledge or procedural knowledge). This distinction plays a crucial role in understanding different forms of cognition and the varieties of knowing that exist in both intellectual and practical domains. The terms reflect two fundamentally different ways that humans engage with the world: through factual understanding and through ability or skill.

Knowledge That (Propositional Knowledge)

Knowledge that refers to knowledge of facts or propositions—knowledge that something is the case. This type of knowledge is typically expressed in declarative sentences and is central to the traditional conception of knowledge as justified true belief. For instance, knowing that water boils at 100°C, that the Earth orbits the Sun, or that Plato was a philosopher are examples of propositional knowledge. Propositional knowledge requires the following components:

1. Belief – The person must believe the proposition.
2. Truth – The proposition must be true.
3. Justification – The person must have adequate reasons or evidence to support the belief.

This formulation, known as the tripartite theory of knowledge, has roots in ancient philosophical thought, especially in Plato’s dialogues, although it has been refined in modern epistemology. Propositional knowledge is often regarded as objective and discursive, capable of being communicated linguistically and analyzed logically.

Philosophers like Bertrand Russell, G. E. Moore, and Edmund Gettier have contributed significantly to discussions about propositional knowledge. Gettier, in particular, challenged the traditional view by demonstrating cases where justified true belief seemed insufficient for knowledge due to the presence of epistemic luck, thus sparking extensive debates about the nature and structure of propositional knowledge.

Propositional knowledge is crucial in science, mathematics, ethics, history, and other fields where explicit statements about the world require justification and validation. It is central to academic inquiry and forms the basis for theoretical understanding across disciplines.