The problem of the criterion. To know which things we know (a theory of knowledge), we need a reliable method. But to justify that method, we need to know it leads to truth. This is a vicious circle: we need a method to identify knowledge, but we need knowledge to validate the method. Every foundational theory (empiricism, rationalism) starts with an unproven assumption. The hard problem is that epistemology, the study of knowledge, cannot get started without presupposing the very thing it seeks to justify. We are like a person searching for their glasses while needing their glasses to see.
Example: "I know the sun will rise tomorrow based on induction (past experience)." The epistemologist asks: "How do you know induction is reliable?" You might say, "It's always worked before." But that's using induction to justify induction—circular reasoning. Any other justification (e.g., it's logically necessary) would require its own justification. The hard problem: We clearly have functional knowledge, but we cannot construct a watertight, non-circular, non-arbitrary account of how we have it. Epistemology either ends in infinite regress, circularity, or an arbitrary stopping point ("just trust your senses, bro"). Hard Problem of Epistemology.
by Nammugal January 24, 2026
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