Some commentators have argued that all particular altruistic acts are directly caused by or reinforced by an internal emotional state. Others argue that rewards obtained by one person might reinforce another person's altruistic act. Yet others argue that all altruistic acts are reinforced by social reciprocation. There are logical and empirical problems with all of these conceptions. The best explanation of altruistic acts is that – though they are themselves not reinforced (either immediately, or delayed, or conditionally, or internally) – they are, like self-controlled acts, part of a pattern of overt behavior that is either extrinsically reinforced or intrinsically reinforcing.