 But when can the other rationally consent? To simplify matters, let us make some background assumptions. Let us suppose that the people who might be used understand what will be done to them and to what purpose, as well as the effects the use will have. Let us also assume that those who might be used have the power to give (or to withhold) consent in the “act-affecting sense” (Parfit 2011: 183–184). When we ask whether they can rationally consent to being used, we are asking whether it would be rational for them to consent (or dissent) supposing that their choice would determine whether or not they were used.