Adapted from Gould 1996.
Others [cf Nitecki 1988] claim that there is only progress because any increase over zero is a net increase, and that different measures will give different results. The traditional notion of progress as an increase in perfection or optimality has been abandoned, for it rested on a view that goes back to the late neo-Platonists - the idea that all of reality is arranged in a heirarchy of increasing perfection. This is called the scala naturae, and is often referred to the Ladder of Perfection. Modern evolutionary science does not think that the path of evolution is a ladder, although Lamarck did. The current view is best summed up by a phrase of Gould's - evolution is a bush, not a tree.
The idea of progress itself was a late medieval notion, taken from the secularisation of theology, especially from the doctrines called 'eschatology' (literally, the 'study of the Last Things') [Ruse 1997].
The 'discovery' of history led to the realisation that biological organisms are historical entities. The view that history was progressive led to the notion that so was the history of life, especially since it led to Man.[note 10] In the nineteenth century, progressivism was rampant, and curiously it always seemed that the ultimate stage was that of the writer, whether it was Marx for the (European) working class, Spencer for the (mostly English) British, or Wagner for the (mostly Prussian) Germans. The first world war came as quite a shock to many, and progress gradually lost its appeal.
Biological systems are historical in two ways: they are the result of irreversible processes (i.e., they grow and die), and they are contingent. the second point is important if you are thinking about what is science in biology. You can't often repeat an event in...