Complex sentence: The first notable self-refuting idea is the Epimenides paradox, a statement attributed to Epimenides, a Cretan philosopher, that "All Cretans are liars", this cannot be true if uttered by a Cretan.
Split into simpler sentences: The first notable self-refuting idea is the Epimenides paradox, a statement attributed to Epimenides, a Cretan philosopher, that "All Cretans are liars". If interpreted as meaning "no Cretan ever speaks the truth," this cannot be true if uttered by a Cretan.