Two explanations of evolutionary progress

Natural selection explains how living forms are fitted to theirconditions of life. Darwin argued that selection also explains what hecalled the gradual advancement of the organisation, i.e.evolutionary progress. Present-day selectionists disagree. In theirview, it is happenstance that sustains conditions favorable to progress,and therefore happenstance, not selection, that explains progress. Iargue that the disagreement here turns not on whether there exists aselection-based condition bias – a belief now attributed to Darwin – but on whether there needs to be such a bias for selection to count as explaining progress. In Darwin''s own view, selection explained progressso far as more complex organisms have the selective advantage whenselection operates unimpeded. I show that these two explanations ofevolutionary progress, selection and happenstance, answer for theirobjectivity to different standards, and for their truth or falsehood todifferent features of the world.