This is arguing in a circle. It's only an "improvement" for someone who already agrees with your ethical and moral claim.

Rational argumentation is fine but it requires that we start with some reasonable premises.

Like any math problem, if you get strange answers it indicates that you're doing the problem wrong. If you divide the circumference of a circle by its diameter and you get something like 31.4 you might wanna check your math.

In this case, if you've "refuted" the idea that racially-based lynchings are universally morally impermissible, you might really wanna look at your math.

Yes, but you aren't doing that. You aren't deriving the conclusion that lynching is wrong from some reasonable premises. You're just asserting it. Another poster downthread did offer a reasonable premise, the golden rule, from which the conclusion that lynching is wrong can be derived. But that doesn't completely solve the problem either; see further comments below.

> if you've "refuted" the idea that racially-based lynchings are universally morally impermissible

This claim is already refuted by human history.

> you might really wanna look at your math

You might really wanna consider that ethics and morality are not math. You can't establish ethical and moral claims simply by deduction. You have to get people to agree to them--or you have to impose them on people by force (and then you have to deal with the ethical and moral problem of justifying such use of force). Even if you have premises that you think are reasonable that support your ethical and moral claims, you still have to get other people to agree to the premises. That's why ethics and morality are hard.

I can't edit out the double negative in my first sentence which makes it incoherent (thanks to HN's time out system) but I can expect that most readers would see that and understand it is a grammatical error, and I'd expect that they'd have a some certainty about their reading of that sentence.

To illustrate why even reasoning from general principles has issues, consider: are you also against punishing people who commit crimes, on the grounds that almost nobody wants to be punished?