https://en.wikipedia.org/wiki/Defeasible_reasoning
In logic, defeasible reasoning is a kind of reasoning that is rationally compelling, though not deductively valid.[1] The distinction between defeasibility and indefeasibility may be seen in the context of this joke:
During a train trip through the countryside, an engineer, a physicist, and a mathematician observe a flock of sheep. The engineer remarks, "I see that the sheep in this region are white." The physicist offers a correction, "Some sheep in this region are white." And the mathematician responds, "In this region there exist sheep that are white on at least one side."
The engineer in this story has reasoned defeasibly; since engineering is a highly practical discipline, it is receptive to heuristics. In particular, engineers cannot and need not defer decisions until they have acquired perfect and complete knowledge. But mathematical reasoning, having different goals, inclines one to account for even the rare and special cases, and thus typically leads to a stance that is indefeasible.
https://en.wikipedia.org/wiki/Category:Reasoning