The interesting thing about your argument, that "libertarianism depends upon truth" is that the people who successfully pushed their brand of libertarianism onto the US political scene reject math and science.
Mission Statement The Mises Institute exists to promote teaching and research in the Austrian school of economics, and individual freedom, honest history, and international peace, in the tradition of Ludwig von Mises and Murray N. Rothbard.
mises.org
The Mises Institute exists to promote teaching and research in the Austrian school of economics, and individual freedom, honest history, and international peace, in the tradition of Ludwig von Mises and Murray N. Rothbard. These great thinkers developed praxeology, a deductive science of human action based on premises known with certainty to be true, and this is what we teach and advocate. Our scholarly work is founded in Misesian praxeology, and in self-conscious opposition to the mathematical modeling and hypothesis-testing that has created so much confusion in neoclassical economics.
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From the very beginning of this strange thing that right wing weirdos call "libertarian ideology", proponents recognized the contradictions between findings based upon hard reality and their beliefs. So they just rejected reality and wrote down "
premises known with certainty to be true" as the basis for Libertarianism as it stands in the US. In other words, they reject facts and cling to unprovable beliefs. Libertarianism of the 50's is a quaint and early form of Qanon.