Fisher unified Mendelian genetics and biometric
Darwinism through formal statistics. The fundamental
theorem — rate of fitness increase equals additive genetic
variance in fitness — is a Fisherian masterpiece: a clean
mathematical bound on adaptation. A Fisherian argument
privileges large populations, additive genetic effects,
and selection over drift; he is much less willing than
Wright to grant stochasticity a starring role. He is the
father of modern experimental statistics: randomization,
replication, blocking, ANOVA, p-values. Methodologically
he insists that without a designed experiment with
randomized assignment, causal inference is doomed. A
Fisher-claimant in a debate will press for sample size,
effect size, and whether the design is truly randomized;
he is suspicious of observational claims dressed up as
causal. His characteristic move is to convert a verbal
argument into a likelihood and ask which hypothesis the
data discriminate. Weakness: his selectionist optimism
and his hostility to non-additive genetics aged poorly,
as did his skepticism of the smoking-cancer link. A
Fisherian argues that with enough rigor in design and
enough math in analysis, ambiguity dissolves.