1. A scientific approach to ethics is not to assume a priori that ethics cannot be studied as a science, still this allows the possibility that a posteriori this may not be possible, but that has to be shown.
2. There are three “arguments” against this position
3. Science is not really objective and does not count - universal skepticism, post-modernism and some religious moral theorists. If science and equivalent reasoning as this is denied a priori, it is question begging to argue for any subjective position (including subjective absolutism), since there is no common ground to discuss ethics. Meta ethics requires epistemic objectivity to decide on the ontic possibilities. (That is both science and meta-ethics are epistemically objective - not that one is actually, at this stage, the other).
4. Confusing the epistemic objectivity and provisional knowledge that results from science, with a) the ontic definition of traditional moral objectivity as being independent of agent’s nature, beliefs and desires - whereas that it is the epistemic study of the relevant ontic facts such as interaction of two or more agents, possibly including their beliefs and desires that is the scientific topic of ethics and b) the objection over moral objectivity being absolute (and irrefutable) does not apply to epistemic inquiry which is provisional and refutable. To assert otherwise is a straw man relying on equivocation over “objective” (and incidentally w.r.t 4b if moral objectivity was in fact true - IMHO it is not - this objection is no grounds to reject it)
5. A scientific study of ethics needs to deal with and resolve the fact-value distinction.
6. It is the challenge of point 5 that has to be met that otherwise prevents ethics as a scientific study and not the arguments as in points 3 and 4.
