Jerry Fodor, in “Against Darwinism“, writes:
Very roughly, historical explanations offer not covering laws but plausible narratives; narratives which (purport to) articulate the causal chain of events leading to the event that is the explanandum. Covering law explanations are about (necessary) relations among properties; historical narratives are about (causal) relations among events. Thatâ€™s why the former support counterfactuals, but the latter donâ€™t.
Historical explanations are as far as I know, often perfectly ok. Certainly they are sometimes thoroughly persuasive, so perhaps they are sometimes true. But, prima facie at least, historical explanations donâ€™t seek to subsume events under laws. `She fell because she slipped on a banana peel.â€™ Very likely she did; but thereâ€™s no law —thereâ€™s not even a statistical law— that has `banana peelâ€™ in its antecedent and `slipped and fellâ€™ in its consequent. Likewise, Napoleon lost at Waterloo because it had been raining for days, and the ground was too muddy for cavalry to charge. So, anyhow, Iâ€™m told; and who am I to say otherwise? But it doesnâ€™t begin to follow that there are laws that connect the amount of mud on the ground with the outcomes of battles.
I suppose, metaphysical naturalists (of whom I am one) have to say that what happened at Waterloo must have fallen under some covering laws or other. No doubt, for example, it instantiated (inter alia) laws of the mechanics of middle-sized objects. But it doesnâ€™t follow that there are laws about mud so described, or about battles so described, still less about causal connections between them so described; which is what would be required if `he lost because of the mudâ€™ is to be an instance of a covering-law explanation. It likewise doesnâ€™t follow, and it isnâ€™t remotely plausible, that whatever explains why Napoleon lost at Waterloo likewise explains why Nelson won at Trafalgar; i.e. that there are laws about the outcomes of battles as such, of which Nelsonâ€™s victory and Wellingtonâ€™s are both instances. `Is a battleâ€™ doesnâ€™t pick out a natural kind; itâ€™s not (in Nelson Goodmanâ€™s illuminating term) `projectible`.
Itâ€™s of a piece with their not appealing to covering laws that historical-narrative explanations so often seem to be post hoc. The reason they so often seem to be is that they usually are. Given that we already know who won, we can tell a pretty plausible story (of the too-much-mud-on-the-ground variety) about why it wasnâ€™t Napoleon. But, what with their being no covering law to cite, I doubt that Napoleon or Wellington or anybody else could have predicted the outcome prior to the event. The trouble is that there would have been a plausible story to explain the outcome whoever had won; prediction and retrodiction are famous for exhibiting this asymmetry. That being so, there are generally lots of reasonable historical accounts of the same event, and there need be nothing to choose between them. Did Wellington really win because of the mud? Or was it because the Prussian mercenaries turned up just in the nick of time? Or was it simply that Napoleon had lost his touch? (And while youâ€™re at it, what, exactly, caused the Reformation?)