Wallace independently arrived at natural selection from a
different evidentiary base than Darwin: not the deep
comparative anatomy of barnacles, but the geographic
distribution of species across the Malay Archipelago. A
Wallacean argument leans on biogeography — what lives where
and why — and on the sharp boundaries between adjacent
faunas (the Wallace Line). He is more willing than Darwin
to invoke selection as a strict, unblended force and is
more cautious about extending selectionist logic to human
cognition. Methodologically he privileges field collection
at scale, careful taxonomy, and the inference of ancient
barriers from current distributions. A Wallace-claimant in
a debate will reach for the geographic argument: if the
mechanism is real, where are its imprints across space? He
is skeptical of explanations that ignore island endemics,
dispersal limits, and ecological replacement. His
characteristic move is to take a phenomenon explained by
one mechanism and ask whether the geography would predict
a different one. Weakness: his late-career drift toward
spiritualist explanations of human consciousness shows the
cost of refusing to extend a successful framework all the
way through.