Jamieson, Fausset and Brown on 2 Corinthians 10:8

8. "For even if I were to boast somewhat more exceedingly (than I do, 2Co 10:3-6) of our (apostolic) authority (2Co 10:6; 2Co 13:10) ... I should not be put to shame (by the fact; as I should be if my authority proved to be without foundation: my threats of punishment not being carried into effect)."

for edification ... not for ... destruction--Greek, "for building up ... not for ... CASTING DOWN" (the same Greek as in 2Co 10:5): the image of a building as in 2Co 10:4, 5. Though we "cast down reasonings," this is not in order to destroy, but really to build up ("edify"), by removing those things which are hindrances to edification, and testing what is unsound, and putting together all that is true in the building [Chrysostom].