 One of the key points in Canguilhem’s argument is that our usage of the term “normal” often conflates two distinct meanings: the usual or typical, and that which is as it ought to be. Consequently, he argues that there can be no purely scientific or objective definition of the normal that allows us to take the theories of physiology and apply them in medical practice, and accordingly we cannot define health as normality either. Instead, according to him, health is that which confers a survival value, particularly adaptability within a set of environmental conditions: “to be in good health is being able to fall sick and recover; it is a biological luxury” (1991: 199). Disease, then, is reduction in the levels of tolerance for the vagaries of the environment. As Mary Tiles (1993) has noted, this emphasis on health rather than normality is a particularly useful tool for enriching contemporary debates over preventative medicine and more generally the trend toward the development of a positive conception of health. Havi Carel (2007, 2008) has contributed to this strand of thought, developing a phenomenological notion of health which emphasizes that health should be understood as the lived experience of one's own body rather than as simply statistically normal bodily functioning in abstract biological terms. Hence she develops an expressly revisionist project, emphasizing that a phenomenological perspective accommodates cases where someone is ill (in biological terms) but healthy, such as in chronic illness.