|Rodney Rawlings writes, "I have sometimes speculated that this humiliation--the anti-Objectivists having a very rhetorically effective last word--was a contributing factor to Rothbard's split from Objectivism. Because he is said to have craved intellectual respectability to a pathological extent." I should think that Rothbard, like Rand, deserves better of his advocates than to be psychologized. Rothbard met his wife at a lecture on Thomist philosophy, so it is likely that he had chosen a Thomist foundation years before he met Rand. Rothbard was attracted to Objectivism because Rand and Aquinas shared many of their slogans, like Reason and Natural Rights. Rothbard split when he discovered that he and Rand used those labels in reference to very different concepts.|
Aquinas and Rand both got their concepts of natural law from Maimonides. Maimonides was a physician and medical scientist, and he discovered that ethics in the Aristotelian sense could be approached as a natural science, based on logical deduction from empirically observed facts of reality. Man, being a biological organism, requires specific, objective conditions in order to live a normal (in the medical sense of healthy, that is happy and long) human life. The function of law in society is to give men these conditions, and the formulation of law, according to Maimonides, is to be approached as a prescriptive natural science, just as finding out what treatment will secure a long and happy life for an individual is the objective of the prescriptive natural science of medicine. Maimonides also equated natural law with Jewish religious law, thus explaining, the ancient observation that those who "walked" the Torah often lived longer and happier lives than those who did not, by his belief that God was both the creator of the natural world and the author of Jewish religious law.
What Rand took from Maimonides was the realization that the purpose of objective ("natural") law was to secure the preconditions of _life qua Man_. According to Rand, one of those preconditions, once men have discovered a way to do so, is the institution of government as a means of placing the use of retaliatory force under objective control. This is necessitated by the fact of reality, that an accuser's judgement of another's innocence is compromised by partiality, by confirmation bias and other biases in the collection of evidence, and by the fact that the accuser can minimize his _eventual liability for having been in the wrong_ by first depriving the suspect of life or limb or freedom, so that the suspect, if innocent, becomes less likely to be able to demonstrate his innocence. So as long as retaliatory force has _not_ been placed under objective control, all men live in fear that one could be forced into imprisonment or combat by another's false belief or dishonest claim. And in a social context in which men already know how to minimize the likelihood of wrongful punishment _by placing the retaliatory use of force under objective control_, it becomes a condition of optimal human life to live without fear that one might be deprived of liberty (or of life itself) without due process of law. Anyone who subjects another to unishment, without first having demonstrated the suspect's guilt by the most impartial and objective procedure available in their social context, has violated the individual rights of everyone around him by his reckless endangerment of their lives and freedoms.
What Aquinas took from Maimonides was the equation of natural law with metanormative principles ordained by God through revelation of religious law. While Rothbard formulated his own, ostensively secular metanormative principles, he took from Aquinas the notion of metanormative principles independent of any actual observation and measurement of the natural world. So it is not surprising that Rand condemned his views as intrinsicist, just as Rothbard, once their differences became clear, condemned Rand's as unprincipled. This had nothing to do with Rothbard's (or Rand's) purported psychopathology. It had to do with their ideas.