Let no man think me foolish (μη τις με δοξη αφρονα εινα). Usual construction in a negative prohibition with μη and the aorist subjunctive δοξη (Robertson, Grammar, p. 933).

But if ye do (ε δε μη γε). Literally, "But if not at least (or otherwise)," that is, If you do think me foolish.

Yet as foolish (καν ως αφρονα). "Even if as foolish." Paul feels compelled to boast of his career and work as an apostle of Christ after the terrible picture just drawn of the Judaizers. He feels greatly embarrassed in doing it. Some men can do it with complete composure (sang froid).