Jamieson, Fausset and Brown on Proverbs 30:2-4

2-4. brutish--stupid, a strong term to denote his lowly self-estimation; or he may speak of such as his natural condition, as contrasted with God's all-seeing comprehensive knowledge and almighty power. The questions of this clause emphatically deny the attributes mentioned to be those of any creature, thus impressively strengthening the implied reference of the former to God (compare De 30:12-14; Is 40:12; Ep 4:8).