While aging research and policy aim to promote ‘health’ at all ages, there remains no convincing explanation of what this ‘health’ is. In this paper, I investigate whether we can find, implicit within the sciences of aging, a way to know what health is and how to measure it, i.e. a theory of health. To answer this, I start from scientific descriptions of aging and its modulators and then try to develop some generalizations about ‘health’ implicit within this research. After (...) discussing some of the core aspects of aging and the ways in which certain models describe spatial and temporal features specific to both aging and healthy phenotypes, I then extract, explicate, and evaluate one potential construct of health in these models. This suggests a theory of health based on the landscape of optimized phenotypic trajectories. I conclude by considering why it matters for more candidate theories to be proposed and evaluated by philosophers and scientists alike. (shrink)

This paper argues that we can see our lives as a snapshot happening now or as a moving picture extending across time. These dual ways of seeing our lives inform how we conceive of the problem of age group justice. A snapshot view sees age group justice as an interpersonal problem between distinct age groups. A moving picture view sees age group justice as a first-person problem of prudential choice. This paper explores these different ways of thinking about age group (...) justice and illustrates them using a principle of respect for human dignity, understood in terms of reasonable support for floor level central human capabilities at each stage of life. I argue that different frames are suitable for different kinds of decisions, and each provides a true, but partial, picture of aging and age group justice. (shrink)

This paper addresses a philosophical problem concerning the ontological status of age classification. For various purposes, people are commonly classified into categories such as “young adulthood”, “middle adulthood”, and “older adulthood”, which are defined chronologically. These age categories prima facie seem to qualify as natural kinds under a homeostatic property cluster account of natural kindhood, insofar as they capture certain biological, psychological, and social properties of people that tend to cluster together due to causal processes. However, this is challenged by (...) the observation that age categories are historically unstable. The properties that age categories are supposed to capture are affected by healthcare and cultural developments, such that people are staying biologically, psychologically, and socially young for longer. Furthermore, the act of classifying people into age categories can bring about changes in their behaviors, which in turn alter the biological, psychological, and social properties that the categories are supposed to capture. Accordingly, I propose that age categories are best understood as interactive kinds that are influenced in dynamic ways by looping effects. I consider some implications of these looping effects for our classificatory practices concerning age, including how different disciplines may need to review the ways they define and use age categories in their inductive inferences. (shrink)

Susan B. Levin argues that the human confidence that an ageless body would be better is irrational. She offers a Kantian-inspired argument to show that human understanding cannot rationally access the experiences of a post-human and ageless existence. We challenge this rationale with a three-step argument: first, an ageless body does not have to be post-human. One should distinguish between the transhumanist projects of life extension and accounts focused on enhancing well-being and quality of life. An existence without aging does (...) not require a radical change in one's temporal intuitions, which makes rational discussion possible. Second, we defend that biological aging does not entail any valuable goods. These goods refer to the chronological dimension of aging. Finally, we argue that biological aging is indeed negative and one may need biotechnological interventions in aging to achieve internal transcendence. Thus, we rationally argue that an ageless body would be better. (shrink)

Both Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eventually cause ageing to evolve. However, the biological literature diverges on the relationship between Medawar’s analysis of the force of selection and Hamilton’s. Some authors appear to believe that Hamilton perfected Medawar’s insightful, yet ultimately erroneous (...) analysis of this force, while others see Hamilton’s analysis as a coherent development of, or the obvious complement to Medawar’s. Here, the relationship between the two analyses is revisited. Two things are argued for. First, most of Medawar’s alleged errors that Hamilton would had rectified seem not to be there. The origin of these perceived errors appears to be in a misinterpretation of Medawar’s writings. Second, the mathematics of Medawar and that of Hamilton show a significant overlap. However, different meanings are attached to the same mathematical expression. Medawar put forth an expression for the selective force on age-specific fitness. Hamilton proposed a full spectrum of selective forces each operating on age-specific fitness components, i.e. mortality and fertility. One of Hamilton’s expressions, possibly his most important, is of the same form as Medawar’s expression. But Hamilton’s selective forces on age-specific fitness components do not add up to yield Medawar’s selective force on age-specific fitness. It is concluded that Hamilton’s analysis should be considered neither as a correction to Medawar’s analysis nor as its obvious complement. (shrink)

Drawing on Ezekiel Emanuel’s controversial piece ‘Why I hope to die at 75,’ I distinguish two types of concern in ethical debates about extending the human lifespan. The first focusses on the value of living longer from prudential and social perspectives. The second type of concern, which has received less attention, focusses on the value of aiming for longer life. This distinction, which is overlooked in the ethical literature on life extension, is significant because there are features of human psychology (...) and the structure of a life that should give pause when considering how long one should aim to live, but which do not neatly coincide with considerations about how valuable additional life is likely to be. I argue that, while Emanuel’s case for hoping to die at 75 is unconvincing, he nonetheless provides weak pro tanto considerations in favour of taking a moderate life span as a prudential aim around which to base at least some significant life plans. (shrink)