"The essential difficulty with divorcing morality from facts is that... there would be no way to resolve moral disputes. Morality would... be... a matter of taste... [I]n... so-called disputes over morality there is... no disagreement over fundamental moral principles, only... over facts. ...[C]onsider ...the abortion issue. There is no dispute over "Thou shall not kill,"... only... whether a fetus is a "person.""