Charles Darwin

Darwin's theory is the high-water mark of nineteenth-century scientific naturalism. Species are not specially created kinds but the product of descent with modification under natural selection; humans are part of the biological order, not exceptions to it.

"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." (Origin of Species, closing paragraph)

A patient empirical realism about the biological world — careful observation across decades, willingness to delay publication until the evidence was secure, refusal to overstate the case in either controversial direction.

"It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most adaptable to change." (Attributed; the actual Darwin formulation in Origin is more cautious: "Those which least depend on continued favourable conditions will be saved.")

A Lockean-Humean empiricism applied to natural history: theory must answer to observation; convenient theory that does not survive observation must be revised.

"Whilst Man, however well-behaved, / At best is but a monkey shaved." (Quoting Gilbert in the Autobiography — Darwin's sense of humour about his own implications)