to reason earnestly with someone against something that person intends to do or has done; remonstrate: His father expostulated with him about the evils of gambling.
c.1534, "to demand, to claim," from L. expostulatus, pp. of expostulare "to demand urgently, remonstrate," from ex- intensive prefix + postulare "to demand." Friendlier sense is first recorded in Eng. 1574.