This can be resolved by realizing that all of Paul's authority is derivative: he receives it from Christ as a special favor, and received also the indwelling of the Holy Spirit. Probably the greatest proof is found in 2 Peter 3:15-16. There Peter refers to Paul as "our beloved brother." He explains that Paul wrote "according to the wisdom given him." Finally, Peter refers to (apparently) a collection of Paul's letters evaluated them as being in the same class as "the rest of the Scriptures," thus giving a clear indication that Paul's writings are indeed truthful and authoritative.
Paul himself says repeatedly it isn't anything personal having to do with his merit. He knows it all rests on what Jesus promised: "But when He, the Spirit of truth, comes, He will guide you into all truth" (John 16:13). The apostles would thus be divinely guided by the Holy Spirit in their teaching and writing.
Well put, Mrs. Don-o.