The problems people seem to be wrestling with are twofold. First, people have been arguing that because value is subjective, we can't say anything about how much value something has except by saying how much someone values it. Second, people have been claiming that because there is no acceptable way to objectively measure utility, it is impossible to coherently make claims about utility which compare utility between one individual and another.
So, I'd like to present my point of view upon those two subjects.
To begin, I want to make clear that I don't deny that utility is subjective. But what does it mean to say this? One uncontroversial, but relatively weak, way of interpreting this is to say that without people (or other valuers) to value things, nothing would have value.
The weakness of this claim derived from the non-practicl conditions it presents, which draw it all to the famous quan of falling tree making/not making any sound. I'd like to present it the other way. If one doesn't know about somthing, this somthing bear no value. A real-life example: When my family came to Israel, we were studiyng Hebrew by reading newspapers. One day I found the an advertisement offering services of "malgezan with his own malgesah". Me and my parents sated to wander, do we, as ahoushold need services of malgezan with malgezah. Naturally, no decision could be reached before we look up the word malgezah in the dictionary.
If it is the nature of value that it does not exist except as it is placed on certain things by people, then it would be impossible to be mistaken about the value of something.
That is the nature of subjecivity. I'll offer my solution a bit later.
The problem arises from the fact that we can talk about something's being "valuable" in two ways. One is positive: "I value X; X is valuable." The other is normative: "X would help me to achieve my ends; X is valuable." When my opponents talk about the subjectivity of value, they slip into the former kind of thinking.
I'd like to rephrase it a bit. "X would help me achieve my ends -> X holds some utility for me -> X is valuable". I did it because the first one sounds like tautology:"I value X; X is valuable" – why do you value X? If " I value X -> X holds some utility for me -> X is valuable" hen there is no difference between the two. If X holds no utility for me, why do I value it? Even most inderect utility will always imply the second definition.
Now enter enterpreneur. Enterpreneur is someone who try to guess other people values and turn it to his profit. In enterpreneureal way "People will pay a lot of money to by Mona Lisa + People will pay alot of money to secure Mona Lisa -> Mona Lisa is valuable. Here is external use of the second way.
In practice, I (and I think most people) do tend to assume that individuals have certain ultimate ends, and that under this assumption, I can largely ignore the issue of the subjectivity of ends. For example, I don't tell the alcoholic, "If you desire the sort of life I find that most people do, you shouldn't have that drink." I simply say, "You shouldn't have that drink." If I were to discover that the alcoholic actually thought that his purpose on the Earth was to explore the effects of alcoholism, producing knowledge for himself and the rest of humanity in the process, then I couldn't criticize his choice of drinking in the same way. But recognizing this possibility doesn't preclude me from assuming that they alcoholic is making a poor decision (in the absence of evidence to the contrary).
A natural problem that people face, is that they mix between their own utility , and enterpreneureal one. They make assumptions about the world arround them, based on their own, subjective of course, scale of values.
One thing that I should address, but I won't, is the issue of justice as it relates to value. It's fully possible that someone could do something which would actually produce the effect of promoting her ends, but we would still want to say that there's something wrong with it.
And here is the catch: If we run along the subjectivity line, as Mises did, we get lost in subjectivity. We'll just find more and more subjective values, which will force us to make more and more claim of uncertainty etc. Just like postmodernists, you finish up denying almost everithing.
I anticipate that it will be necessary to offer something by way of disclaimer. It occurs to me that by suggesting that something can be more valuable to one person than to another person, I will be accused of being a Utilitarian--of claiming that the person to whom the thing would be most valuable should be the one to have it.
Can people lost in subjectivity develop such Utilitarism? In oreder to make calim about somthing being more valueble you must prove it. But surprise, surprise, all is subjective! No way to show who values somthing more.
There is one place where the difference in values is manifested, and it is ruled by Utilitarism. It is the market, wher people exchange things with lesser value for things with greater value. BUT the market hold no "should"s. It is voulantary. So it is possible to make claim of subjectivity of value without copulsive utilitarism.
My argument is positive, and not normative. In saying that interpersonal utility comparisons are, in at least some cases, possible, I am not saying anything about what ought to be done in cases where these comparisons show that one person would benefit more than another from some policy, or where one person would gain more than another would lose.
But in the world of Mises, lost in subjectivity it is impossible. The'll reject the "maybe, in some cases, yet positive".
This implies that we cannot in fact decide whether two pense have more utility to a millionaire or a beggar. Yet we may have a shrewd suspicion. But this, we are told, is "unscientific," for lack of a test." He continues, "Can we afford to reject this very clear finding of common sense? Of course great caution must be exercised in not pushing the matter too far. Since the evidence is vague, we must not go farther than a very clear mandate from common sense allows."
Which is easily explained by what I've said in the beggining. The "Shrewd suspicion" comes from our own scale of values. But since it is subjective we are, once again, lost in subjectivity.
How to get out? How to avoid being lost in subjecivity? Why people get lost in the first place? Lets go back, to John Locke. In his "An Essay Concerning Humane Understanding" , he shows that no idea is innate. But it means that many of interpersonal concepts like "justice", "natural rights", "democracy", " equal rights", or any other concept you would consider important, can be found inside human paradigm a-priori. So, digging inside the scale of values not only will nor reveal them, but rather reveal their absence. That's how "subjective justice" comes to live, and how people get "lost in subjectivity".
What is the solution? Well, there is famous one, used in many civilisations. I've found it both in Talmud and in Ayn Rand. And by that name you can guess what it is – setting independent objective standard. With this standard, people can , instead of evaluating two subjective value scales- to compare their utilty with the standard. Does creation of the standard block or disrupt personal freedom? By no way. It only says that the life of child in Africa worth more than 2$. It is up to you to decide which utility is greater – the cup of cofee, or moral satisfaction from saving a child ( or perhaps moral satisfaction of havig cofee while lesser beings are doomed to perish). Having this standard allows wxistence of justice beause all refer to the standerd to know that it is better to steal than to starve, but it is better to have just 4 rooms and not 6 than robbin a bank.
Because the robber also knows that, the justice is not built upon subjective vlues, but upon objective action and decisions of people aware of different values.