convincing
From LSJ
Ποιητὴς, ὁπόταν ἐν τῷ τρίποδι τῆς Μούσης καθίζηται, τότε οὐκ ἔμφρων ἐστίν → Whenever a poet is seated on the Muses' tripod, he is not in his senses
Of persons or arguments: P. and V. πιθανός.
Of arguments: P. ἀναγκαῖος, V. εὐπειθής, πειστήριος.
