Human enhancement is a much debated topic in the bioethical literature. Human beings have long tried to improve their capacities and their performances through training and with the aid of tools; but more recently new means have come to the fore, such as drugs and biotechnological devices, especially in the domain of bodily strength and cognitive powers. Moral enhancement has been more seldom discussed. However, this question has recently been hotly debated between two philosophers, Thomas Douglas and John Harris. Douglas claims that modulating certain ugly emotions directly would consist in moral progress-directly, that is, without using cognitive means like persuasion or deliberation. Harris makes three objections against this thesis: such a direct neuromodulation would be inefficacious, would put our liberty in jeopardy and would lead to a moral decline. In this paper, I examine the third argument: with direct modulation, we risk intervening too much or too little, inducing an inappropriate emotion or an inappropriate level of an otherwise appropriate emotion-two upshots that will put morality in jeopardy. I conclude that the validity of this objection depends on several meta-ethical positions: if you are a rationalist or think that intentionality and consciousness are at the core of morality, you will agree with Harris, but if you are a sentimentalist or someone for whom results count, you will disagree. Here as elsewhere, ethical questions cannot be divorced from meta-ethical ones.