Contrary to this claim, however, there is not one 'libertarian philosophy' but a number of philosophical defences of libertarianism from philosophers with very different perspectives. In particular, some libertarian philosophers provide consequentialist, and even utilitarian, defences of libertarianism. As far as I understand libertarianism it involves a rejection of government financing of and support for abortion. And, while abortion remains a controversial moral issue, libertarians would also have to reject a government ban on performing abortions. There are a number of people who consider killing animals, or at least other mammals, to be murder.
Moral positions differ over time.
Abortion is one issue that, partly due to the improvements in technology that Mr Clarke mentions, has become more controversial. Libertarianism, as a social theory, provides no obvious defence for either side of the argument. It is quite ironic, given his rejection of utilitarianism as collectivist, that there is a collectivist mentality running throughout Mr Clarke's article. Mr Clarke constantly talks as if abortion decisions are made by a group of abortionists and the mothers just happen to be carriers of the aborted foetus. Although Mr Clarke rejects consequentialist arguments as collectivist, I believe that they are useful in shedding some light on the issue of state involvement in abortion.