One can imagine a kind of hormonal arms race or genetic arms race, whether it's to do with height or IQ, conceivably, in the future. So it's limitless, and that's another of the features that sets it apart from medical intervention.

Other animals can make sounds, and sounds can indicate pleasure and pain. But language, a distinctly human capacity, isn´t just for registering pleasure and pain. It´s about declaring what is just and what is unjust, and distinguishing right from wrong. We don´t grasp these things silently, and then put words to them; language is the medium through which we discern and deliberate about the good.

If you go back to Adam Smith, you find the idea that markets and market forces operate as an invisible hand. This is the traditional laissez-faire market idea. But today, when economics is increasingly defined as the science of incentive, it becomes clear that the use of incentives involves quite active intervention, either by an economist or a policy maker, in using financial inducements to motivate behavior. In fact, so much though that we now almost take for granted that incentives are central to the subject of economics.

Whether you're a libertarian liberal or a more egalitarian liberal, the idea is that justice means being non-judgmental with respect to the preferences people bring to public life.

My argument is not that we must never intervene in nature. My argument is that there is a moral difference between intervention for the sake of health, to cure or prevent disease, and intervention for the sake of achieving a competitive edge for our kids in a consumer society.

It's ultimately the purpose of education to cultivate the love of learning for its own sake.

In natural pregnancy, more than half of fertilized eggs fail to implant or are otherwise lost. Should we regard that as an instance of infant mortality? And if so, why are we not mounting ambitious public health campaigns to try to save and rescue all of the fertilized eggs that are lost in natural pregnancy? We would need a public health campaign of massive proportions if there really were over a fifty percent rate of infant mortality.