A.T. Robertson Commentary 1 Corinthians 3:20

"and again, The Lord knoweth the reasonings of the wise that they are vain." — 1 Corinthians 3:20 (ASV)

And again (κα παλιν). Another confirmatory passage from Ps 94:11.

Reasonings (διαλογισμους). More than cogitationes (Vulgate), sometimes disputations . Paul changes "men" of LXX to wise (σοφων) in harmony with the Hebrew context.

Vain (ματαιο). Useless, foolish, from ματη, a futile attempt.