When several causes contributed to an outcome, we often
single out one causal factor as being “more of a cause” than
others. What explains this selection? Existing research
suggests that people’s judgements of actual causation can be
influenced by the degree to which they regard certain events as
norm-deviant, or “abnormal” (Hart & Honoré, 1963;
Kahneman & Miller, 1986; Hitchcock & Knobe, 2009; Halpern
& Hitchcock 2015). In this paper, we argue that statistical
abnormality influences causal judgements about human agents
by changing the agents’ epistemic states (Epistemic
Hypothesis). In Experiment 1, we replicate previous findings
that people assign more causal strength to a statistically
abnormally acting agent, but show that they also assign them
more knowledge about the behaviour of their peers. In
Experiment 2, we show that in case of equal epistemic
uncertainty, people do not differentiate between statistically
abnormal and normal causal agents. In Experiment 3, we
explore the difference between type and token abnormality,
and find that a token abnormal, but type normal behaviour still
influences causal judgments, with people’s epistemic
judgments mirroring these causal judgments. We discuss the
implications of this research for current norm-frameworks in
causal cognition.