Abstract: The approach to progress allows an apparently simple analysis of scientific rationality: a transition in practice is rational just in case it is generated by some procedure that would be expected to yield progressive modifications of practice. It is shown how this standard can be articulated in a number of different ways. The issue of the rationality of scientific revolutions is then posed, and addressed by developing a compromise model that draws both from the logical empiricist tradition and from the historical objections to it.

Keywords: logical empiricism, rationality, scientific rationality, scientific revolution,