Too often, we as individuals do things that harm us, that seriously interfere with our being able to live in the way that we want. We eat food that makes us obese, that promotes diabetes, heart failure and other serious illness, while at the same time, we want to live long and healthy lives. Too many of us smoke cigarettes, even while acknowledging we wish we had never begun. We behave in ways that undercut our ability to reach some of our most valued goals, despite education and despite incentives to choose the right thing. What should be done?

If I were to try to harm someone else in a way that alters his future seriously and perhaps irrevocably for the worse, I would be stopped. When it comes to hurting myself, though, we have a common belief that it is wrong to interfere, even if I foresee that I will very much regret what I have done, often when it is too late to fix what I have let happen. I think this makes no sense. If it is permissible, even obligatory, to stop me when I do something that seriously interferes with someone else's chances of achieving the life he wants, I think …