What assumptions about human beings did Mill presume that might make his ideas problematic?

Question

(RELATING TO LIBERTY) What assumptions about human beings did Mill presume that might make his ideas problematic?

Answer 1

Schadenfreude
"Mill furthermore dealt with one of the prime problems associated with utilitarianism, that of schadenfreude. Detractors of utilitarianism argued, among other objections, that if enough people hated another person sufficiently that simply reducing the happiness of the object of their hatred would cause them pleasure, it would be incumbent upon a utilitarian society to aid them in harming the individual. Mill argued that, in order to have such an attitude of malice, a citizen would have to value his own pleasure over that of another, and so society is in no way obligated to indulge him, and, to the contrary, is fully permitted to suppress his actions."
http://en.wikipedia.org/wiki/J._S._Mill