How should ethics help decide the morality of enhancing morality? The idea of morally enhancing the human brain quickly emerged when the promise of cognitive enhancement in general began to seem realizable. However, on reflection, achieving moral enhancement must be limited by the practical challenges to any sort of cognitive modification, along with obstacles particular to morality’s bases in social cognition. The objectivity offered by the brain sciences cannot ensure the technological achievement of moral bioenhancement for humanity-wide application. Additionally, any (...) limited moral enhancement will not easily fulfil ethical expectations. Three hypothetical scenarios involving putative moral enhancement help illustrate why. Philosophical concerns about the “Does-Must Dichotomy” and the “Factor-Cause Plurality,” as I label them, forbid easy leaps from views about morality on to conclusions about ways to enhance morality, and then further on to ethically justifying those enhancements. A modest and realistic approach to moral enhancement emerges from exploring these issues. (shrink)