Philosophical Background

It is certain that Menger is of the Aristotelian tradition.  There is no dispute with that.  All sources I've come across, including the Mises Institute own historian David Gordon, confirms that Menger was as Menger had written privately to some people about his Aristotle background, one writing includes his son, another to Walrus, as noted in a paper by Barry Smith.

From all the writings I've come across it appears that Mises didn't debate Rothbard's natural law definition.  Also I haven't come across any papers by Rothbard in which he argues against Mises on this point.  In one article in which Rothbard rebuts a Professor Gonce in which Gonce was trying to make the case that Mises affirmed the natural law of the Aristotelian-Thomist tradition (A-T) in his own writings, but Rothbard in that paper rebuts Gonce in two ways.  (1) He shows that Mises was not talking about A-T but was mainly referring to the natural law of the natural sciences in some of his books, one being Socialism, I can't think off-hand what any other books were.  Rothbard then goes on to (2) point out that Mises doesn't addressed the natural law of the A-T tradition when Mises argues against natural law.  For those knowledgeable about A-T it is easy to pick out that Mises attacks the Thomas Hobbes version, though Mises is not explicit as to what version he is attacking.  The reader simply has to know the differences.  Knowledge is pertinent in so many ways in so many fields in so many endeavors in life in general.  It is clear that in the rare political books that Mises undertook "Liberalism", Mises says that a 'liberal is to protect life, liberty, health, and private property'.  Those are undeniably John Locke's specific natural rights.  Locke included health which has to do with pursuit of happiness or arete/excellence.  But that is for another day, so, to move on.

I don't know if that's a final result concerning if Mises ever addressed the natural law of A-T tradition.  That article explains it more, but I have found no others.  It shows that Mises though against natural rights, he never refuted or attempted to refute, it appears, the A-T version.  My conclusion thus far is Mises not having contact with Aristotle other than through Menger (Barry Smith's article above discusses this and I believe David Gordon writes about this as well but of course his biography might say in more detail which I haven't read).  In that region, ie. Germany and Austria, was under the heavy influence of Thomas Hobbes and Spinoza's natural law.  Heinrich Rommen's mainly history book on natural law talks about this at length including how the Nazi's subverted natural rights rhetoric in order to appeal to the masses.  It appears that Menger being in Austria and having massive access to Aristotle, something changed over the decades that confounded and dispersed Aristotelian in that region because by Mises time natural rights were being subverted by the Nazi's for their own propaganda.  They used natural rights in the same way that the U.S. gov't does currently by saying things like healthcare is a right or Brussel's declaring that vacations are a right.  Clearly not of the A-T tradition in their rhetoric.  But Rommen cover's more of this in his historical book.

This is all underlined by a deep debate between Hume and Kant that appears to be on-going today but I have yet to realize to what extent the current debate is.  After reading a phenomenological article yesterday which is philosophical in nature but is mainly an article on the history of phenomenology.  It was written by the extant philosopher Josef Seifert.  It sorts through the historical connections of Franz Brentano who was the teacher of Edmund Husserl and the latter considered the founder of phenomenology.  Seifert wrote a book (dated 1997) that appears to delve more thoroughly into the philosophy of phenomenology but also, I haven't read the book yet, but when I was skimming through the footnotes at the end of the book I read about this underlying Kant v. Hume debate once again that appears to be on-going in philosophical circles.  Seifert also mentioned a much deeper debate though that is between the Thomist school v. Scotist in those footnotes.  Phenomenology is of the Brentano strain, the Kant philosophical strain, and Thomas Aquinas.  Phemenology is influenced, like most philosophies in the west by Aristotle and Plato too.   Here's Seifert's book called "Back to the Things Themselves".  Barry Smith who is a philosopher does work in Austrian economics and is cited by Seifert more than once in that book.

Here's some other article's that E.R. had linked deep in another thread in one of his posts:

First article with Rothbard and Reinach (Reinach was a phenomenologist) by Walter Block

Second Article some more info. on what I'm calling the long debate (Kant v. Hume or what might also be called Thomist v. Scotist).

The debate between Kant and Hume isn't necessarily one sided, meaning, one side ends up winning when the dust settles.  What is happening is discourse.  It's philosophy at it's best in which argumentation on both sides realize that enough time or development in certain areas of previous philosophical developments had happened.  A lack of knowledge is pointed out in such an area and so as it all comes to head various philosophers in a certain time era who may acknowledge the lack of philosophical development will take it on.  It can be very fruitful. 

The lack of knowledge that Hume was pointing out was in Arisotle's "First Principles", also known as assumptions, self-evident, axioms, aprior, intuition, common sense, and primitive sense.  In a related way this certainly has to do with sensory experience and empiricism too.  Aristotle, and others after him, didn't spend much philosophic discourse on these first principles because as Aristotle paraphrasingly said in one of his works A Prior 'there has to be a starting point in which logical deductions take place and knowledge is acquired and to try to deduct first principles would arise the need to use the first principles themselves in order to make the logical deductions'.  Clearly that is impossible to prove what has to be used in order to prove itself.  Infinite regression would happen if a starting point isn't found and used.  Hume questioned these First Principles and Kant rebutted him.  Philosophy has been in the midst of argumentation ever since it appears.  Hume academic skeptism was prevented from entering the natural sciences by Karl Popper and his falsification proposition (though Popper wouldn't have called it a proposition).  But since Karl Popper's falsification can't be applied to the social sciences, then Humean skepticism remains in those sciences to various extents undoubtedly depending on how some people interpret Hume and to what extent they use Hume.  Because Kant hasn't been refuted either.  Phenomenology is focused on that part of philosophy that deals with first principles and because so, it is a full philosophy in and of itself as it works to show the distinctions between empirical or sensory science and philosophy (first principles, logic, etc...).  Barry Smith had this to say about Hume (I linked this already above but just pointing out where this particular quote comes from):

"Indeed, great difficulties may be set in the way of our attaining knowledge of essential structures of certain sorts, and of our transforming such knowledge into the organized form of a strict theory. Above all we may (as Hume showed) mistakenly suppose that we have grasped a law or structure for psychological reasons of habit. Our knowledge of structures or laws can nevertheless be exact. For the quality of exactness or strict universality is skew to that of infallibility. Episteme may be ruled out in certain circumstances, but true doxa (which is to say, `orthodoxy') may be nonetheless available."

It's not that Hume has to be refuted, as I already noted, but it's not that Kant has to be refuted either in total for both.  Barry Smith makes a good point here.  It may be that Hume and Kant were simply strengthening certain aspects of philosophy that don't necessarily negate each other but undoubtedly may through what philosophy does best over time, ie. discourse, argumentation, revise each other, better affirm each other, and possibly continue to yield fruit as certain knowledge about a certain aspect in the then known philosophical discourse can be added to.

To end this I would like to point out an important figure in all of this.  Franz Brentano is an important figure to help historically tie this together.  I haven't read any of his works yet other than quotes of him in other article's written by other people.  It is debatable to what extant Brentano influenced Carl Menger.  David Gordon has his take and Barry Smith has another take.  But Brentano is definitely part of this picture because he was Aristotelian too.  Hume had a psychological slant to his philosophy whereas Brentano had a logic slant.  Seifert calls this distinction one of psychologic and logic.  One Mises himself was aware of when he makes the clear distinction that praxeology is not psychology.  Brentano is a direct  precursor to phenomenology being Husserl's teacher who Husserl is considered the founder of phenomenology.  Franz's name comes up quite a bit in the search engine at the Mises Institute.

This post was mainly to demonstrate the depth to the historical development of economics which is grounded in and developed from philosophical backgrounds - as all sciences are.