"From my understanding of “marginal values”, i was always under the impression that “marginal values” refers to the axiom that value is relative to person, space and time. "
No. I’m sorry but you’re confusing the terms “marginal” and “subjective”.
The term marginal, in an economic sense, refers to the fact that things are valued based upon the use value derived from the addition of one additional unit of a homogeneous good. For instance I will value ice cream based upon my use value for each additional unit of ice cream. The significance of marginal utility analysis is that this reflects itself within price, as units of goods are based upon each additional unit of the good, its marginal utility, as opposed to the total utility. Originally this solved the infamous “water and diamonds paradox”, which asked “If water is more useful than diamonds, why is it that diamonds are much more valuable than water?” The answer is, of course, that water is valued based upon its total supply, and you will value one more gallon of water based upon its utility alone, not the utility that you will derive from all the water you own.
Subjectivity implies that it depends entirely upon a single actor’s state of mind. This will then mean that he will have different values than everyone else, and that these values will change based upon a large number of different factors. Because value is merely internal, it changes with the actor’s state of mind and understanding of his universe.
"I am trying to figure out how to apply praxeological methods to ethics in order to make an evaluation of a given scenario. "
I’d be happy to try to help you out as much as possible. Now Theory and History can give you a somewhat good idea of what Mises’ believed, but it might not be much help other than that. Other books that I’d look into are Mises’ Human Action. Just the first 50 pages or so should tell you just about everything you need to know about the praxeological method. If you need reinforcement on the matter there’s this short essay by Rothbard, the first chapter of Man, Economy, and State, Menger’s treatise which covers almost exclusively the matter of subjective valuation (although it’s not strictly speaking praxeology) especially in chapter 3, and Hoppe’s whole book devoted to the topic of reinforcing subjectivist ideals in the realm of the social sciences. Once again, your problem is going to be on finding any work done to evaluate ethics with the science. I’m not sure that you’ll find it here in this book, I’ve never read it but you might find some relevant work in Rothbard’s The Ethics of Liberty, especially on chapter 26 which seems to be a critique of Misesian utilitarianism, and in MES above, the final section of which is entitled “Anti-Market Ethics: A praxeological critique” which should at least give you an idea of how praxeology can be used within the ethical realm. Finally, for a better understanding of exactly what Austrian Economics is and how its methods are used, I’d look at this essay.
The only users around here who I think could help you are Vive and Dave, both of whom might be willing to help out.
A major thing for you to remember:
Praxeology is supposed to be value-free. This means that ends cannot be critiqued, we cannot say that the fact that someone wants X is stupid, it can only judge the means, I.E that choice Y is a stupid way to get there.
That’s about all the advice that I can give you. I really hope that helps you, and I hope I didn’t utterly overwhelm you with sources