  Harry Frankfurt (1984) asks how needs must be understood if they are to have the special moral significance that we attribute to them relative to mere desires. He argues that we must distinguish between free volitional needs, where an item is needed only to satisfy a desire over which a person has control—he could choose not to have it; constrained volitional needs, where an item is needed to satisfy a desire a person cannot rid himself of, such as an addiction; and non-volitional needs that are entirely independent of desires, such as a sick person’s need for medicine. Only in the case of the latter two categories of need will a person be harmed by being denied what she needs, Frankfurt argues, and it is only these needs that have the special moral force that the language of ‘need’ is usually understood to convey.