The first point JEK makes relies on a quotation I presented in which R.F. Harrod pointed out that if we completely reject the possibility of comparing utility between people, then we must acknowledge that it is impossible to say whether two pence is more valuable to a beggar than a millionaire. Harrod's point is to show that complete rejection of interpersonal utility comparison is unreasonable. Common sense tells us that as long as we assume that this is a typical beggar and a typical millionaire, then obviously we can say that the two pence is more valuable to the beggar.
But JEK disagrees. He/she is willing to bite the bullet, saying, "That is the nature of subjectivity." This point is expanded on later in the post with the argument that our common sense intuition "...comes from our own scale of values." This seems to me an important point. I think that JEK is right in suggesting that the reason we think that the beggar would value the two pence more is that we believe that if we were the beggar, we would value the two pence more than we would if we were the millionaire. If we had no such intuition, then it does not seem unreasonable to say that we might not be able to arrive at any decisive view on the matter.
When we acknowledge this, we are faced with the realization that we are not the beggar, and we are not the millionaire. If we assume that all of the individuals involved are basically the same, then it seems obvious that the beggar would value the two pence more. But in light of the clear probability of important differences existing between the beggar and the millionaire, it becomes somewhat more difficult to know for sure how to compare them.
As Menger wrote in his book, Principles of Economics:
What one person disdains or values lightly is appreciated by another, and what one person abandons is often picked up by another. While one economizing individual esteems equally a given amount of one good and a greater amount of another good, we frequently observe just the opposite evaluations with another economizing individual.
Additionally, Harrod writes:
Consider the Repeal of the Corn Laws. This tended to reduce the value of a specific factor of production--land. It can no doubt be shown that the gain to the community as a whole exceeded the loss to the landlords--but only if individuals are treated in some sense as equal. Otherwise how can the loss to some--and that there was a loss can hardly be denied--be compared with the general gain?
To this point, I am in complete agreement with JEK. However, where we part company is JEK's implication that we therefore cannot compare the utility that could be gained by the beggar to the utility that could be gained by the millionaire. Is it really conceivable that the beggar and millionaire are so different that even this seemingly obvious comparison is invalidated (remember, we're talking about a normal beggar and a normal millionaire)? I don't think that this is a reasonable position.
Perhaps it will help to put it this way. Could you actually imagine a case where the millionaire and the beggar were both normal people, and the millionaire would actually gain more utility? Let's say that first, you (magically imbued with all of the millionaire's values and desires) got to experience the millionaire's experience in getting the two pence, and doing with it whatever he would do with it. Immediately after, you were magically transported back in time to experience the beggar's version of the same experience (now miraculously having the beggar's values). Then, the situation was flipped, and you got to experience the beggar's getting the two pence from both sides. After this magical episode, do you really think there would be any possibility that you would say that the beggar didn't benefit more? It seems like however we define wellbeing and utility, as long as we do so in a way that wouldn't be completely absurd, and as long as the beggar and millionaire are normal people, we would come out of the experiment saying that the in getting the two pence, beggar's utility was augmented by a greater amount.
JEK's second argument restates my proposed claim, "I value X; X is valuable" as "X would help me achieve my ends -> X holds some utility for me -> X is valuable." He/she then explains that this is the same thing as my alternative proposed claim, "X would help me achieve my ends; X is valuable." If the first claim is restated the way that JEK proposes, this seems obviously true. In fact, the only difference is JEK's addition of a middle step.
But the problem is that "I value X; X is valuable" cannot be correctly restated as "X would help me achieve my ends -> X holds some utility for me -> X is valuable." The acceptable restatement, using this form, would be "I believe that X would help me achieve my ends -> I believe that X holds some utility for me -> X is valuable." This reliance on the beliefs of the valuer is the critical difference. JEK writes, "If X holds no utility for me, why do I value it?" The clear answer is that I value it because I am mistaken about its ability to help me in achieving my ends.
JEK attempts to offer a solution to the problem of interpersonal comparisons of utility in the form of an "independent objective standard" with which individuals could "compare their utility." Unfortunately, I'm not exactly sure what JEK is getting at; if individuals could compare their utility with a metric, and that metric were an objective standard, then it would follow that utility could be measured using that metric. Because I don't believe that JEK believes that we could measure utility, I must simply be misunderstanding. But hopefully what I've said here will be useful in some capacity.