In the physical sciences a theory can be postulated and then an environment created to test the theory and to prove the theory but even in the physical sciences there are theories that are beyond the ability to create an environment for testing. Then other means are used in parallel, to cross reference, as a way of proving the likelihood of the theory.
In the human sciences this kind of empiricism is not the appropriate methodology but even if it was it would be way too messy to try to test theories in that way since humans are subjective. Apriorism is part of the subjective methodology and this enables theory to go beyond the here and now.
With regards natural order, expecting “a single example from history where this presumed natural state of affairs has existed” is way too absolute. There have been numerous relatively-better examples in history that are not just coincidentally compatible with the theory of natural order.
But if you understand science using the methodology of subjectivism you can prove the validity of the theory by logic and reason which is why it is such a powerful scientific method. Not coincidentally it is a method that acknowledges the greatness of its subject (human beings) and it is a method that leads to theories that advance civilization.
It is true that there has yet to be a perfect example of a natural order but there has also never been a period or place when human affairs have not been subjected to ego-driven interpretation and ego-driven intervention. Those periods where these influences were relatively less happen to coincide with the periods of relative peacefulness and prosperity, this we know.
To assume that a natural order is not possible (to ignore the contributions made by many great thinkers) is to sell science and religion short, to sell economics and ethics short, and to sell the nobility of the human race short.
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