Causality Across the Levels: Bio-Social Mechanisms Federica Russo Philosophy, Kent

The project Causality in the health sciences: Establishing, evaluating, using causal claims Learn (modelling), Do (policy) Causality across the levels Vertical: individuals and populations Horizontal: biological and social 2

The levels The intuition: What to do depends on what one knows Vertical level: Interplay between generic and single-case both at the modelling and policy level Horizontal level: Health have both biological and social causes 3

“The strange case of obesity, nutrition, and physical activity” Dr Jekyll: Causes and effects of obesity, role of diet and of physical activity look clear and quite well understood 4

“The strange case of obesity, nutrition, and physical activity” Mr Hyde: Causes and effects of obesity, role of diet and of physical activity are far from clear and are poorly understood In need of further investigation, e.g.: Adipose tissue as a pro-inflammatory, pro-thrombotic endocrine organ affecting the cardiovascular system [EoO] Lipid infiltration as a cause of target organ injury in the cardiovascular system [EoO] Obesity-associated hypertension and hypertensive renal disease [EoO] Cardiovascular adaptations to obesity during various stages of development and maturation, from childhood through adolescence [EoO] Hyperinsulinemia, insulin resistance, and other endocrine deregulation syndromes of obesity as related to cardiovascular disease [CoO and EoO] Gender differences in risk of CHD at given degrees of overweight [CoO] … [From a recent request for application of NIH, US] 5

What makes the obesity case interesting The mechanism itself is poorly understood Epidemiological studies give hints on the mechanisms: Something interesting concerning hypothesis formulation? Environmental and biological factors are involved: Theoretical issues Policy issues Two questions: The effects of obesity on health The causes of obesity To be distinguished: ‘causative’ and ‘preventative’? Causal assessment ≠ prevention But philosophers treat causes and preventatives alike 6

What paper awaits to be written? … And for whom? “Should public health policies be causally-based Lessons from the studies on obesity, nutrition and physical activity” Possible argument structure Evidence-based public health: valuable intention, but ‘evidence’ left too much in the fog In particular, distinction type I and type II evidence does not answer the question of what evidence is needed Causal criteria à la Hill again do not spell out what evidence Causally-based public health policies: 1 Difference-making (descriptive epidemiology) 2. Mechanisms (analytic epidemiology) 3. Levels (vertical and horizontal) Policies to take these 3 aspects into account as much as possible 7