Matthean Discourses 1: What is a composite discourse, and why should you care?

This week I begin a new series on the claim that Matthew contains composite discourses of Jesus. I define the phrase "composite discourses," discuss reasons for caring whether Matthew contains them, and read interesting quotations from D.A. Carson giving some reasons for questioning the scholarly consensus on this. Is Carson a "critical scholar"? How is the phrase "critical scholar" used equivocally to bludgeon people into agreeing with a conclusion? Do we really have independent reason to believe that there was a known compositional device of producing composite discourses while giving what appears to be a single historical setting for a speech?