Full Idea
Didactic arguments are those which reason from the principles appropriate to each branch of learning and not from the opinions of the answerer (for he who is learning must take things on trust).
Clarification
'Didactic' argument aims at converting people to a view
Gist of Idea
Didactic argument starts from the principles of the subject, not from the opinions of the learner
Source
Aristotle (Sophistical Refutations [c.331 BCE], 165b01)
Book Reference
Aristotle: 'Sophistical Refutations, On the Cosmos etc (III)', ed/tr. Forster,E.S. /Furley,D.J. [Harvard Loeb 1955], p.15