> So you are (at least partially) defining ethics by the consensus of people (in your case professional philosophers).
I am not. I'm saying that people on HN make some very hasty assumptions about ethics (e.g. the claim made in the parent comment) that ethicists broadly agree are deeply misguided. I'm hoping to encourage a little more caution. Ethics are not defined by what professional philosophers agree on, but professional philosophers are in a good position to point out when lay comments are making simple mistakes in their reasoning. This is such a case.
So you are (at least partially) defining ethics by the consensus of people (in your case professional philosophers).
Even in pure mathematics, which is considered to be among the most rigorous of fields, a whole lot depends on consensus about axioms and consensus about what is a valid proof.
Yes, I agree there are logical principles for determining ethical actions given a set of ethical axioms, but however, the ethical axioms themselves, and indeed the logical principles, are determined by consensus.