> Are there good historical examples of this happening, where foundational knowledge is completely lost? Maybe not quite in the context you were asking, but ph

> Are there good historical examples of this happening, where foundational knowledge is completely lost? Maybe not quite in the context you were asking, but philosopher Alasdair MacIntyre argues as the premise in his book After Ethics that this is what happened to the philosophy of ethics after antiquity. Copypasting from its Wikipedia article [0]: > [After Ethics] begins with an allegory suggestive of the premise of the science-fiction novel A Canticle for Leibowitz: a world where all sciences have been dismantled quickly and almost entirely. MacIntyre asks what the sciences would look like if they were re-assembled from the remnants of scientific knowledge that survived the catastrophe. > He claims that the new sciences, though superficially similar to the old, would in fact be devoid of real scientific content, because the key suppositions and attitudes would not be present. "The hypothesis which I wish to advance", he continues, "is that in the actual world which we inhabit the language of morality is in the same state of grave disorder as the language of natural science in the imaginary world which I described." Specifically, MacIntyre applies this hypothesis to advance the notion that the moral structures that emerged from the Enlightenment were philosophically doomed from the start because they were formed using the aforementioned incoherent language of morality. [0] https://en.wikipedia.org/wiki/After_Virtue https://en.wikipedia.org/wiki/After_Virtue