This book argues that moral changes such as the abolition of dueling, slavery, and foot-binding are not the result of new understanding of why they are undesirable. They result from changes in how they affect the honor (or status) of the groups that have the power to create the change.

Dueling was mostly associated with a hereditary class of gentlemen, and feeling a responsibility to duel was a symbol of that status. When the nature of the upper class changed to include a much less well defined class that included successful businessmen, and society became more egalitarian, the distinction associated with demonstrating that one was a member of the hereditary elite lost enough value that the costs of dueling outweighed the prestige.

Slave-owners increasingly portrayed the labor that slaves preformed in a way that also implied the work of British manual laborers deserved low status, and rising resentment and political power of that labor class created a movement to abolish slavery.

The inability of Chinese elites to ignore the opinions of elites in other nations whose military and technological might made it hard for China to dismiss them as inferior altered the class of people whom the Chinese elites wanted respect from.

These are plausible stories, backed by a modest amount of evidence. I don’t know of any strong explanations that compete with this. But I don’t get the impression that the author tried as hard as I would like to find evidence for competing explanations. For instance, he presents some partial evidence to the effect that Britain abolished slavery at a time when slavery was increasingly profitable. But I didn’t see any consideration of the costs of keeping slaves from running away, which I expect were increasing due to improved long-distance transportation such as railroads. He lists references which might constitute authoritative support for his position, but it looks like it would be time-consuming to verify that.

Whether this book can help spark new moral revolutions is unclear, but it should make our efforts to do so more cost-effective, if only by reducing the effort put into ineffective approaches.

This book starts out with relatively uninteresting articles and only the last quarter of so of it is worth reading.

Because I agree with most of the arguments for enhancement, I skipped some of the pro-enhancement arguments and tried to read the anti-enhancement arguments carefully. They mostly boil down to the claim that people’s preference for natural things is sufficient to justify broad prohibitions on enhancing human bodies and human nature. That isn’t enough of an argument to deserve as much discussion as it gets.

A few of the concerns discussed by advocates of enhancement are worth more thought. The question of whether unenhanced humans would retain political equality and rights enables us to imagine dystopian results of enhancement. Daniel Walker provides a partly correct analysis of conditions under which enhanced beings ought to paternalistically restrict the choices and political power of the unenhanced. But he’s overly complacent about assuming the paternalists will have the interests of the unenhanced at heart. The biggest problem with paternalism to date is that it’s done by people who are less thoughtful about the interests of the people they’re controlling than they are about finding ways to serve their own self-interest. It is possible that enhanced beings will be perfect altruists, but it is far from being a natural consequence of enhancement.

The final chapter points out the risks of being overconfident of our ability to improve on nature. They describe questions we should ask about why evolution would have produced a result that is different from what we want. One example that they give suggests they remain overconfident – they repeat a standard claim about the human appendix being a result of evolution getting stuck in a local optimum. Recent evidence suggests that the appendix performs a valuable function in recovery from diarrhea (still a major cause of death in places) and harm from appendicitis seems rare outside of industrialized nations (maybe due to differences in dietary fiber?).

The most new and provocative ideas in the book have little to do with the medical enhancements that the title evokes. Robin Hanson’s call for mechanisms to make people more truthful probably won’t gather much support, as people are clever about finding objections to any specific method that would be effective. Still, asking the question the way he does may encourage some people to think more clearly about their goals.

Nick Bostrom and Anders Sandberg describe an interesting (original?) hypothesis about why placebos (sometimes) work. It involves signaling that there is relatively little need to conserve the body’s resources for fighting future injuries and diseases. Could this understanding lead to insights about how to more directly and reliably trigger this effect? More effective placebos have been proposed as jokes. Why is it so unusual to ask about serious research into this subject?

This book tries to derive ought from is. The more important steps explain why we should choose the one-box answer to Newcomb’s problem, then argue that the same reasoning should provide better support for Hofstadter’s idea of superrationality than has previously been demonstrated, and that superrationality can be generalized to provide morality. He comes close to the right approach to these problems, and I agree with the conclusions he reaches, but I don’t find his reasoning convincing.

He uses a concept which he calls a subjunctive relation, which is intermediate between a causal relation and a correlation, to explain why a choice that seems to happen after its goal has been achieved can be rational. That is the part of his argument that I find unconvincing. The subjunctive relation behaves a lot like a causal relation, and I can’t figure out why it should be treated as more than a correlation unless it’s equivalent to a causal relation.

I say that the one-box choice in Newcomb’s problem causes money to be placed in the box, and that superrationality and morality should be followed for similar reasons involving counterintuitive types of causality. It looks like Drescher is reluctant to accept this type of causality because he doesn’t think clearly enough about the concept of choice. It often appears that he is using something like a folk-psychology notion of choice that appears incompatible with the assumptions of Newcomb’s problem. I expect that with a sufficiently sophisticated concept of choice, Newcomb’s problem and similar situations cease to seem paradoxical. That concept should reflect a counterintuitive difference between the time at which a choice is made and the time at which it is introspectively observed as being irrevocable. When describing Kavka’s toxin problem, he talks more clearly about the concept of choice, and almost finds a better answer than subjunctive relations, but backs off without adequate analysis.

The book also has a long section explaining why the Everett interpretation of quantum mechanics is better than the Copenhagen interpretation. The beginning and end of this section are good, but there’s a rather dense section in the middle that takes much effort to follow without adding much.