Motives and merits of counterfactual histories of science

I consider the motives of historians devising counterfactual histories, analyze the narrative structure of these histories, and assess their merits. Richard Evans attacked counterfactual histories as motivated by wishful thinking. And he claimed that they could not contribute anything to the understanding of the past because they are concerned "with pointing out supposedly preferable alternatives." Both claims can be refuted with two particular counterfactual histories of biology. An analysis of the narrative structure of counterfactual histories suggests objective criteria that can distinguish those that have been designed, in order to reach a certain narrative ending, from those that were open-ended at the beginning. These criteria are then applied to two examples from the history of biology: Bowler's Darwin Deleted and Radick's 'Other Histories, Other Biologies.' Radick did not determine his counterfactual in advance, to meet a certain narrative ending. This refutes the first claim (wishful thinking). Bowler self-avowedly did design his counterfactual in advance, but its narrative ending still contributes to understanding. In particular, it shows that the idea of natural selection is not necessarily associated with its social discontents. This refutes the second claim (cannot contribute to understanding).