Kate Lynch (Macquarie University): Causal Information and the Norm of Reaction

Behavioural and quantitative geneticists routinely employ the heritability statistic to make causal claims about the ‘nature’ and ‘nurture’ of a given trait. These studies investigate the relative effects of genetic and environmental differences on differences in a phenotype. The proportional effect on phenotype due to genetic variation is summarised in the heritability statistic (H2 or h2). Since Richard Lewontin’s influential (1974) paper, there has been debate about the utility of the heritability statistic for making causal claims. Some, like Lewontin, argue that a more useful and informative approach to apportioning the causal responsibility of genetic and environmental variation is the norm of reaction (NOR). The NOR is a visual representation of individual genotypes in a population, and their phenotypic effects over various environments. Lewontin argues that the NOR is superior to the heritability statistic as it conveys causal information which H2 does not. But just how such information is conveyed and exactly what that information is remains underdeveloped. In line with Lewontin, will argue that the NOR presents information about causal relationships between genotype, environment, and phenotype that the heritability statistic does not. I demonstrate this by appealing to the concepts ‘stability’ and ‘invariance’ outlined by Woodward (2003, 2010) under his interventionist framework for causation. These features can be used to distinguish causal relationships and assess their relative explanatory depth, and can be ascertained using an NOR and not a heritability statistic.

References
Lewontin RC, 1974, ‘The analysis of variance and the analysis of causes’, American Journal of Human Genetics, vol. 26, pp. 400-411.
Woodward J, 2003, Making Things Happen: A Theory of Causal Explanation, Oxford & New York, Oxford University Press.
Woodward J, 2010, ‘Causation in biology: Stability, specificity, and the choice of levels of explanation’, Biology and Philosophy, vol. 25, no. 3, pp. 287-318.

Date & time

Tue 16 Feb 2016, 4:00pm to 6:00pm

Location

Coombs Seminar Room A

Event series

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