pleader
From LSJ
Δύο γὰρ, ἐπιστήμη τε καὶ δόξα, ὧν τὸ μὲν ἐπίστασθαι ποιέει, τὸ δὲ ἀγνοεῖν → Two different things are science and belief: the one brings knowledge, the other ignorance
advocate: P. and V. συνήγορος, ὁ or ἡ, σύνδικος, ὁ or ἡ. P. παράκλητος, ὁ.