Abstract
M.A. (Philosophy)
The purpose of my dissertation is to ask the question, what non-statistical reality
underlies heritability claims? But in order to ask this question, I must deal with the
prior question – does it ever make sense to causally interpret heritability claims? The
consensus answer to this question is “no”. Firstly, I argue that is possible to reply to
each of the main lines of argument used to establish that heritability estimates are
causally uninterpretable – (i) the existence of gene-environment interaction, (ii) the
existence of G-E correlation, and (iii) the locality of heritability estimates. Therefore
the consensus that “heritability estimates are devoid of causal implications” (Sesardic,
2005:10) is too quick. Specifically, (a) when there is no statistical gene-environment
interaction (Sesardic, 2005; Tal, 2009, 2012), (b) when there is small to no geneenvironment
correlation (Tal, 2009, 2012), and (c) within the domain of populations
that have similar causally salient features, it makes sense to causally interpret a
heritability estimate as a measure of the causal strength of differences in genes on
total phenotypic variance.
Secondly, when a heritability estimate is correctly used to express a causal fact, I
argue that it suffers from the same problem that other measures of strength of
association suffer from – the causal interpretation problem (or CIP). That is, when we
say that heritability is a “measure of the proportion of the variance in a particular trait
in a particular population that is attributed with genetic variation in that population”
(Kaplan, 2006:56), the mathematics does not tell us how to interpret “attributable
to/with”. Viewed in this light, the epistemological problem about heritability analysis...