ABSTRACT
Amartya Sen's 1992 Darwin Lecture1 asks how evolutionary success should be evaluated - in terms of the reproductive success of the species (or genotype) or quality of life. Sen draws attention to the difficulties in both sets of criteria: measuring progress in terms of reproductive success is arbitrary and crass, but measuring it in terms of quality of life risks being anthropocentric. I hope to broaden and clarify still further some of the implications of the problem he addressed by examining a selection of other writers who have considered it since it was first discussed in the nineteenth century by Herbert Spencer. Spencer was a far from satifactory thinker on evolution, but in his early work, The Principles of Psychology (1855), he identified a set of criteria which seem to be genuinely objective.
