In the last half of the twentieth century, legalized segregation ended in the southern United States, apartheid ended in South Africa, women in many parts of the world came to be recognized as having equal rights with men, persons with disabilities came to be recognized as having rights to develop and exercise their human capabilities, colonial peoples' rights of self-determination were recognized, and rights of gays and lesbians have begun to be recognized. It is hard not to see these developments as examples of real moral progress. But what is moral progress?
In this book, William...

In the last half of the twentieth century, legalized segregation ended in the southern United States, apartheid ended in South Africa, women in many parts of the world came to be recognized as having equal rights with men, persons with disabilities came to be recognized as having rights to develop and exercise their human capabilities, colonial peoples' rights of self-determination were recognized, and rights of gays and lesbians have begun to be recognized. It is hard not to see these developments as examples of real moral progress. But what is moral progress?
In this book, William...

"We hold these truths to be self-evident..." So begins the U.S. Declaration of Independence. What follows those words is a ringing endorsement of universal rights, but it is far from self-evident. Why did the authors claim that it was? William Talbott suggests that they were trapped by a presupposition of Enlightenment philosophy: That there was only one way to rationally justify universal truths, by proving them from self-evident premises.

With the benefit of hindsight, it is clear that the authors of the U.S. Declaration had no infallible source of moral truth. For example, many of the...