The importance of not tolerating intolerance is something that’s been long understood as critical in free societies.

Karl Popper is a philosopher famous for elucidating the philosophy of science and the scientific method, but he’s also known for his Paradox of Tolerance, his observation that “if a society is tolerant without limit, its ability to be tolerant is eventually seized or destroyed by the intolerant.”

Popper clearly understood that not all ideas are equal or equally deserving of debate or even discussion. He knew that tolerating intolerable ideas leads to fascism.

Libertarians and those of us on the left who embrace tolerance and free exchange of ideas ought to very carefully consider Popper’s warning.