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.

I am trying to get at the moral arguments and the ethical status of various attempts at enhancement, or genetic engineering, or the bid for designer children. But there are implications for society at large.

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.

First, individual rights cannot be sacrificed for the sake of the general good, and second, the principles of justice that specify these rights cannot be premised on any particular vision of the good life. What justifies the rights is not that they maximize the general welfare or otherwise promote the good, but rather that they comprise a fair framework within which individuals and groups can choose their own values and ends, consistent with a similar liberty for others.

It is true that the Jewish tradition emphasizes the moral mandate to save life. It also has a different position from the Catholic Church on the moral status of the embryo. It has a more developmental view of when human life, in the sense of personhood, begins than does the Catholic Church.

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.

It's possible to make sense of what's morally at stake in an appreciation of the gift of life, or the gift of a child, without necessarily presupposing that there is a giver. What matters is that the gift - in this case, the child - not be wholly our own doing, our own product.