In classical logic, the Principle of Bivalence dictates that every declarative sentence must be strictly true or strictly false, with no middle ground.

Because Epimenides was from Crete himself, his statement creates a paradox where if he is telling the truth, he must logically be lying.

This phenomenon is known as self-reference, a concept in logic where a subject creates an unresolvable loop by making claims about its own properties.

In the classic Star Trek episode "I, Mudd", Captain Kirk famously uses a variation of this logical trap to confuse and disable a hostile android.