Is it a claim, or a thesis that is put forth as a kind of null hypothesis — something that it is morally right to accept unless there is evidence against it? I think the latter.
Thus take a debate about slavery, or women’s rights. If Jones claims that some people (say blacks) yearn to be slaves, and that women can only be satisfied when they follow orders and are beaten if they don’t, and that we must grant blacks and women what they dearly want, then Jones has the responsibility to provide evidence. A pretty heavy responsibility in fact. If Smith says that no one yearns to be a slave, or to be beaten if they don’t follow orders, we don’t require that he provide evidence. That’s a moral judgment, and I think a correct one. But that’s weaker than the claim that humans yearn for freedom. And if someone asks for scientific proof, they simply don’t understand the nature of science.
You could have found the same in investigating slave societies: slaves who tell you how much more secure they are being ordered and beaten than in having to make their own choices. Or patriarchal societies; the same — and it’s still very much alive in this case. An important step in the struggle for freedom is simply “consciousness raising”: helping people — ourselves and others — come to understand that they are oppressed, that their subordinate role is not a necessity of life. Nor is it a psychological necessity; rather, an abandonment of one’s basic rights, including the right to realize one’s full potential. People of course have the right to give up their basic rights, but if we care about them, we have a responsibility to help them understand what they are doing, and why. And it applies to ourselves too.
Take, say, women’s rights. If you had asked my grandmother whether she is oppressed, she probably wouldn’t have understood what you are talking about; that’s life. If you’d asked my mother, you’d have found that she resented it, but accepted it, as life. If you’d ask my daughters, they’d tell you to get lost. That reflects hard-won victories for freedom.