In his thoughtful defence of very modest moral enhancement, David DeGrazia1 makes the following assumption: ‘Behavioural improvement (ie, ‘greater conformity to appropriate moral norms and therefore a higher frequency of right action’) is highly desirable in the interest of making the world a better place and securing better lives for human beings and other sentient beings’. Later in the paper, he gives a list of some psychological characteristics that ‘all reasonable people can agree … represent moral defects’. I think I am a reasonable person, and I agree that most if not all items on the lists do represent moral defects—I certainly would regard them as such in a close family member or friend. But if I were in the business of ‘making the world a better place and securing better lives for human beings and other sentient beings’, I would hesitate to prescribe moral enhancement (or therapy—the distinction does not matter for my purposes) for everyone with these acknowledged defects. A lot of good work, from removing tumours to negotiating treaties, may be best done by people with serious moral defects.

For a simple consequentialist, a moral defect is just a trait that tends to make the world a worse place. Not being a consequentialist, I think that moral defects should be identified independently of their tendency to produce worse outcomes. For this reason, I think it's necessary to qualify DeGrazia's starting assumption—I think behavioural improvement may sometimes be undesirable if our goal is to make the world a better place. My reasons will be familiar to readers of Bernard Williams.

As …