In other words, they often do NOT join. Hence no explanation focusing only on one phenomenon is of any interest. An explanation is needed for _both_ phenomena.
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Specifically, it seems absurd on the face of it to assume that the Vendee & the KKK share any significant features. The attempt to make a single explanation fit both is absurd.
We are back to finding the essence that unites Jonathan Apples and changing styles in work shirts.
Carrol