The Final Authority: Logic
John C. M?daille wrote: 
?Now, Mises may be right in all of this, but he is methodologically wrong. He does not offer this as a conclusion of the science of psychology, but as a "self-evident" principle. And even that would not have been so bad had he offered some discussion of what determines a ?self-evident" axiom. But he does not. He offers on his own authority only. This is not science, but the essence of ideology.?
Well, I guess it is worthwhile to talk a bit about what is self-evident, why the self-evident is the starting point of science, and whether a proper scientist can offer his own authority only.
1.   Something is self-evident if anybody looking for evidence finds it. Its presence is not conditional on the observer being aware of something prior to seeing the evidence. That is, it must not be the conclusion from some other science such as ecology, psychology, or hydrology.  If economics must begin from a conclusion of psychology, which science should be the mother to generate the premise for psychology, and where would it ultimately regress to? The proper question is: what is so unique that a separate science of economics is warranted? (The answer: exchange is the unique event that no science other than economics can explain. To a psychologist, exchange is totally unintelligible. Was there ever a psychologists who could explain why one produces what he does not wish to consume, and consumes what he does not bother to produce? Will it ever be able to explain why nearly everybody is eager to give up real goods for money, but rarely willing to undertake real goods in barter for real goods?)
2.   Bertrand Russell wrote: ?My desire and wish is that the things I start with should be so obvious that you wonder why I spend my time stating them. This is what I aim at because the point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it.? (Russell 1918, The Philosophy of Logical Atomism, p-53)
Mises wrote a long discourse on human action, and the bulk of the treatise tries to show the obvious, because the fatal sin of the superstitious masses is that they refuse to see the obvious. Here is an example: the superstitious masses before Copernicus observed the diurnal motion of the earth (the change of day into night into day) but never managed to see the obvious necessity that the earth must be spinning if it is has to undergo day after night after day.  Everybody except Copernicus was wrong, and the authority of the billions and billions of people over millions of years who saw the sun rising and setting had no merit at all when the authority of Copernicus alone was sufficient. Why? Well, use some geometry or algebra: if a statement is true, it must be possible to state it mathematically. You need no authority other than that of logic, expounded as mathematics. Why? Reality has no ability to violate (valid) logic. Mises understood this so well that he wanted the term praxeology (logic of practice= logic of action) as the name of a science of human action. The suffix ?logy? in praxeology has a very obvious connotation: it is science precisely because it has logic. (Correct logic never contradicts facts. If facts contradict an argument, the argument is illogical.)
3.   Now, fallacy of authority is that the truth of a statement does not in any way depend on who stated it. To search for authority is the very glare of superstition. No, Mises should by all means offer things on his own authority alone. His authority is based on his command over logic. Mises had originality. If he had to rely on the authority of anybody else, why would we read Mises instead of the original author cited by him? 
4.   It would have been a great day of joy if there were people who could read Mises and understand him. Sadly, Mises made himself inaccessible to most readers, because he refused to draw pictures and write equations to satisfy the low-level aspiration of tired souls. People without sufficient curiosity need the vulgarities such as the idea that D(x)=S(x) determines the price of x, where D(.) and S(.) represent demand and supply functions of good x. Curious people would wish to know what the term price meant, and they would be self-assured that the price of x is the quantity of y, when y is the payment for x ( and y may be a real good of current period or future period or an artifice called money). But as soon as one defines the price of x as the quantity of y per unit of x, one sees that the equation D(x) =S(x) can in no way determine the quantity of y that pays of x (namely the ratio y/x). Of course the huge masses that believe that the equation D(x) =S(x) determines price (y/x) are all wrong because the statement is illogical. By contrast, if there is just one person who says that price of x is determined if the equation is v(x) = v(y), then that one person alone is right, because the statement is logically valid ( as the ratio y/x is price of x if and only if value of x is equal to value of y).  Indeed, it remains true even if there is not a single authority to state it. Even before Newton stated the law of gravitation, it was true. 

Mohammad Gani