Jamieson, Fausset and Brown on James 2:4

4. Are ye not ... partial--literally, "Have ye not made distinctions" or "differences" (so as to prefer one to another)? So in Jude 22.

in yourselves--in your minds, that is, according to your carnal inclination [Grotius].

are become judges of evil thoughts--The Greek words for "judges" and for "partial," are akin in sound and meaning. A similar translation ought therefore to be given to both. Thus, either for "judges," &c. translate, "distinguishers of (that is, according to your) evil thoughts"; or, do ye not partially judge between men, and are become evilly-thinking judges (Mr 7:21)? The "evil thoughts" are in the judges themselves; as in Lu 18:6, the Greek, "judge of injustice," is translated, "unjust judge." Alford and Wahl translate, "Did ye not doubt" (respecting your faith, which is inconsistent with the distinctions made by you between rich and poor)? For the Greek constantly means "doubt" in all the New Testament. So in Jas 1:6, "wavering." Mt 21:21; Ac 10:20; Ro 4:20, "staggered not." The same play on the same kindred words occurs in the Greek of Ro 14:10, 23, "judge ... doubteth." The same blame of being a judge, when one ought to be an obeyer, of the law is found in Jas 4:11.