Which branch of philosophy studies the nature and extent of knowledge?

The branch of philosophy that studies the nature and extent of knowledge is known as epistemology. This field of study delves into questions concerning the nature of knowledge, its presuppositions, sources, limitations, and validity. Epistemology examines how knowledge is acquired, what justifies beliefs, and the distinction between belief and knowledge. It seeks to understand the criteria we use to determine what we can claim to know and the methods by which we arrive at those claims.

The other branches mentioned have distinct focuses: metaphysics deals with the nature of reality and existence; logic concerns the principles of valid reasoning and argumentation; and ethics examines questions of morality and values. By understanding how these branches differ, it becomes clear why epistemology specifically addresses knowledge and its characteristics.