Praxeology is a set of conceptual tools about the theory of action. It is the basis of economic theory. Whereas much has been fleshed out about the economics of human action, there is little about the ethics and natural rights of human action.
Aristotle starts his ethics with every aim seems to fulfill some good. Mises starts his ethics with every human action is purposeful. Ayn Rand and Murray Rothbard are explicitly like Aquinas or Aristotle. One must say something generally about virtue. Mises says praxeology can advise you on means not ends.
Thinking of ethics is not linear deduction; it is network. You ground ethics in subjective value.
The first of ten lectures from the Foundations of Libertarian Ethics seminar with Roderick T. Long.