"We are lucky that we are so different," Thomas Sowell writes, "so that the capabilities of many other people can cover our limitations." But more than this, Sowell argues, the inequality of abilities (or "diversity," one might say) we see in human beings can save lives and enhance "everyone's well-being." Yes, human beings are created equal, as the Declaration of Independence so appropriately notes. This fact of life affirms the ontological worth and significance of the human being. It expresses the basis upon which people are to be respected by the powers that be and not steamrolled by big government,...