This retrospective, or backward-looking, use is closely connected with praise and blame, punishment, and desert. When something has gone wrong, we invariably want to know who was at fault; and when something has gone right, we occasionally stop to ask who acted well. This is the topic of retrospective responsibility.
RACA [ISBE] RACA - ra'-ka, ra-ka'> (rhaka, Westcott and Hort, The New Testament in Greek with Codices Sinaiticus (corrected), Vaticanus, Codex E, etc.; rhacha, Tischendorf with Codices Sinaiticus (original hand) and Bezae; Aramaic reqa', from req, empty): Vain or worthless fellow; a term of contempt used by the Jews in the time of Christ.
Smith's Bible Dictionary. a term of reproach derived from the Chaldee reka, worthless. (Raca denotes a certain looseness of life and manners, while 'fool,' in the same passage, means a downright wicked and reprobate person.) (Matthew 5:22). term of reproach derived from the Chaldee reka, worthless. (Raca denotes a certain looseness of life and manners, while 'fool,' in the same passage, means a downright wicked and reprobate person.) (Matthew 5:22).