THE ADVANCE OF SCIENCE AND SCIENTIFIC REVOLUTIONS

Scientific revolutions in biology do not conform to the description of such revolutions as given by T. Kuhn. Instead, several paradigms may coexist simultaneously for long periods of time, and succeeding paradi gms are not necessarily incommensurable. Biological revolutions are no t separated by long periods of normal science; rather, there are alway s minor revolutions and theory changes of various magnitude. Kuhn's th eory is in good agreement with essentialistic philosophy, while theory change in biology fits Darwinian evolutionary epistemology, consistin g of variation (the continuing proposal for new theories) and selectio n (the survival of the successful ones). Nowadays there is very little dissent (at least among scientists) from the thesis that science make s steady advances and that, as a result of these advances, we are gain ing an ever improving understanding of the world. What is, however, hi ghly controversial is how these advances occur. This controversy occup ies a large portion of the literature of contemporary philosophy of sc ience. Leaving a number of minor movements aside, one can distinguish two major schools, Kuhn's theory of scientific revolutions (and normal science) and Darwinian evolutionary epistemology. I shall not discuss the latter.1