People often complain that others -- often others who oppose abortion or destruction of embryos in the lab -- are just trying to implement their own religious views into law, and how they are trying to force their moral views on others. The argument isn't that the particular view about when life begins, or about whether abortion is proper, is mistaken; I can respect such arguments, and I even agree with some of them. Rather, instead of confronting the pro-life position on the controversial and difficult to debate merits, the arguer claims that this position is somehow procedurally improper, because it rests on religious reasons or forces moral views on others.

But all judgments about when human beings acquire certain rights rest on unproven and unprovable moral calls. (I have made this argument more broadly before, but I think it's even clearer as to abortion.) Moreover, they all force one's moral views on others. If you think people acquire a right to life at birth, and you thus support infanticide bans, then you're forcing your moral view on others who want to kill babies. If you think that ninth-month abortions are wrong, because the baby acquires rights at viability, then you're forcing your moral view on others who want to abort fetuses that are eight months old.

Now of course these judgments may be informed by medical observations -- for instance, when the brain develops to a certain level, or when something will end up naturally growing into a born human without any further intervention -- or by pragmatic considerations, gut feel, opinion polls, tradition, views about how precise and clear legal lines should be, or whatever else. But ultimately these judgments rest not on the scientific or social facts as such, but on moral judgment calls about how one evaluates these facts.

Likewise with libertarian arguments about the rights of the woman; the scope of the woman's rights, the existence or not of the fetus's or baby's rights, and how one reconciles those rights ultimately rests on one's own axioms about morality. And whether one supports a law against all abortion, against late-term abortions, against infanticide, or against killing babies who are one year or older, one is forcing one's moral views on others.

Ah, but at least you're forcing moral views on others, not forcing religious views on them, some say. So what? How is (1) someone's gut feeling that an eight-month old fetus is so much like a baby that surely it shouldn't be killed a more legitimate basis to write laws than (2) someone's deduction from the Bible that any fetus can't be killed? For that matter, how is a secular moral axiom that born babies are as entitled to live as we are a more legitimate basis to write laws than a religious moral axiom to the same effect?

All of us draw lines in this field, whether at conception, viability, birth, or whenever else. None of us can prove the validity of those lines through science or through abstract logic.

Those of us (like me) who draw secular lines shouldn't feel superior to those who draw religious lines here -- and we certainly shouldn't think that the Constitution or political morality somehow makes our linedrawing more proper. We can and should debate, as best we can, where the lines should be drawn, but we should recognize that at some point it comes down to the unproven and unprovable, for the secular among us as well as for the religious. And we should realize that no attempt to protect children from killing -- wherever you draw the line about what constitutes a "child" -- can operate without forcing one's moral views on others.