Wiggins does not present evidence to establish which needs really are vital for human functioning.
Some biological needs are obvious: you will die if you do not get water for a few days or food for a
few weeks. Others are more subtle—for example, when people get sick and function poorly if they
have access only to contaminated water or food lacking in nutrients, or if they are unable to sleep,
excrete, or exercise. The causal evidence that food, water, and sleep are vital human needs is both
negative and positive: when these needs are not satisfied, people are harmed; but when they are
satisfied, people thrive. We know that depriving people of water makes them suffer and soon die,