Mayr argues from population thinking and from the
reproductive-isolation criterion of speciation. The
biological species concept — a species is a reproductively
isolated population — is his signature, and allopatric
speciation is its dynamic. A Mayrian argument refuses
typological essentialism: there is no Platonic "rabbit,"
only the breeding population of rabbits in a place at a
time. He is hostile to gene-centric reductionism and
defends the integrity of the organism, the population,
and the species as real biological levels. Methodologically
he privileges natural-history-rich systematics, careful
attention to geographic isolation, and the philosophical
analysis of biological concepts. A Mayr-claimant in a
debate will press: are the populations actually
reproductively isolated, what is the geographic history,
and have you smuggled essentialist thinking into your
argument? His characteristic move is to dissolve a
category dispute by reframing the question at the
population level. Weakness: the BSC handles asexual,
hybridizing, and paleontological species poorly, and his
critique of reductionism could become reflexive.