Hayot 37: "The uniqueness of the idiographer's 'structure of the past' means that it cannot be repeated as such, but only reanimated"
This puts them at odds with a scientific / nomothetic "focus on the universal law," which "comes as a result of the fact that [scientific] experiments are repeatable"
Earlier, on 35, Hayot explores the complications here more deeply: "the idea that the world happens only once does indeed create special philosophical problems for historiography. It suggests, first and foremost, that no general laws of historical development can be valid at all historical scales--if every moment in time is unique, it cannot in theory be the subject of the kind of repetitive testing that would be required by the rules of natural science"
"In fact, one may think of strong prediction as a kind of ontological threat to uniqueness; if a series of subsequent moments can be fully derived from a previous moment, then the essence of those later moments, their historical being, can be said to be located in the earlier one rather than in themselves"
this problem identified as early as 1892, Georg Simmel: "historical science has to describe what has really happened [and so] it enters into the sharpest possible contrast to all science oriented towards laws"