It isn't an argument from ignorance. I'm not saying, "I have no idea what motivates people, therefore it must be pleasure". Plenty of nice people say they enjoy being nice. I just take their word for it if they say they derive pleasure from helping others. Is that not normal? Are the truly good people out there miserable? This nun you mention, do you imagine she's unhappy with her life? If she was, would you still call her a good person?
So you prefer the fallacy of Composition, then? The reasoning remains erroneous.
People don't always enjoy what they do. Some may, and on occasion many will, but often you don't. Yet you slog on, as it is the right thing to do. I happen to think that a person that hates their life, gets nothing from it, but acts selflessly within it because they see the need for their acts, is laudable.
Have you read war memoirs? How disillusioned they become, yet a vague sense of duty or patriotism drives them on. It is a paradox. There comes a point where people don't care about the opprobrium of desertion or a court martial, but where a idea still drives them on. A good example here, is For Whom the Bell Tolls of Hemingway (although not a memoir, he did fight in the Spanish Civil War). People's motivations are complex, and to assume it all goes down to a basic averting risk of pain and seeking pleasure, I frankly find puerile.
There are many other examples, such as women working as prostitutes to support children that aren't even their own, or social workers and doctors trying to stave the great flood of human misery that enters their doors.
But as I said, there is no way to disprove this assertion, especially if held as a sort-of article of faith, as many do.
That's just nonsense. I'm not the only one who likes chocolate ice cream. For everyone else that likes chocolate ice cream, we hold an intersubjective value together. I don't need to force people to say they like it even if they don't. I don't assume either. Without prompting, plenty of people will say, "I like chocolate ice cream". So why is it that they are likely lying? But of course, another person who disagrees with me has to bring up terrible things to attempt to argue against my claims. "Look how awful this view makes you feel! You can't say terrible, horrible things are factually the wrong thing to do!".
Somebody, please tell me, am I the only one to notice the irony of using an appeal to emotion to argue against my "all values are subjective" claim and to argue for the "there are objective values" claim?
Feel free to show me how Intersubjective values can be crafted from purely Subjective viewpoints, then. This is the same problem I alluded to earlier, where it was argued by Gaara that your subjective viewpoint is the only objective data. There is no way to assume a subjective viewpoint corresponds to any other's. Is your appreciation of a movie the same as someone else's? Do your tastebuds for that matter, conjure the same physical sensation (they don't by the way, hence some people have better palates, and tastes change as you age)?
You miss the point though. No one cares about people liking ice cream. If some like it more, others less, or some wax lyrical about it, that is immaterial. It is the implication of your thought, that this somehow corresponds to morals. For then those that really care WILL seek to enforce their opinion and it is therefore Will to Power at play here. That would be the only way for any form of 'right action' to occur. It is not about appealing to emotion, but disabusing you of this weird idea that such thinking is innocuous. Have you read Dostoyevsky? This is the classic problem of Raskolnikov in Crime and Punishment, or Rogozhin in The Idiot. Just because you personally don't think in this manner, does not mean others won't; nor use this reasoning in support thereof. You have no way to disagree then, except by enforcing your own set of values over theirs.
Essentially it would argue that whomever can enforce it, that others maintain a society by it, and that can subjectively argue its merits to themselves, so justifies it - that way leads to Gulags, book burnings and the gates of Auschwitz.