  Consider next the alleged normative force of need claims. They are often singled out for discussion because on the one hand whether somebody has a need seems to be a matter of fact, while on the other the existence of the need once established seems to constitute a reason for acting so as to fulfil it. If John, who has a migraine, needs a painkiller (matter of fact), then I have a reason to give him one (normative reason). So needs serve as a bridge between ‘is’ and ‘ought’. Yet leaving aside general doubts as to whether such bridge-building is possible, we need to tread cautiously here. First, the thesis is only plausible in the case of categorical needs. In the case of instrumental needs, everything will turn on the end for which the needed item is required. An arsonist may need a match to start a fire, but there is no reason to hand him one. Second, even categorical needs only provide reasons for action when the need is presently unfulfilled. So we need to draw a distinction between ‘occurrent’ and ‘dispositional’ needs (Thomson 1987, 11–12; Reader 2007, 71). A dispositional need is a general need that human beings have, like the need for sleep. But whether a person has an occurrent need for sleep depends on whether he has just woken up after a good night’s rest or on the contrary has been unable to sleep for the last twenty-four hours. It is only in the latter case, where the need is occurrent, that others have a reason to meet it by offering the sleep-deprived person a bed to lie on.