...there's nothing wrong with being extra critical of rhetoric that's historically dubious.
Yes there is. It biases our thinking.
Here is a non-controversial example of this: "Millikan measured the charge on an electron...got an answer which we now know not to be quite right...It's interesting to look at the history of measurements of the charge of an electron, after Millikan. If you plot them as a function of time, you find that one is a little bit bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher.
Why didn't they discover the new number was higher right away? It's a thing that scientists are ashamed of - this history - because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong - and they would look for and find a reason why something might be wrong. When they got a number close to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that..."
(The narrative comes from Richard Feynman.)
If we look on some hypothesis extra critically, and others only reasonably critically, we will bias our views towards the beliefs which we apply less scrutiny to.
Good point, but that narrative feels a lot like a specific example of sloppy science and poor measurement.
I'm going to stand by the notion that extraordinary claims require extraordinary evidence, even if that may create a small bias toward conventional thinking.
What's an "extraordinary claim"? And also, why do claims that are "historically dubious" automatically fall into the category of "extraordinary"?
In Bayesian terms, it sounds like you are merely stating that you assign a very small prior to the "natural reasons" hypothesis. I.e., you are claiming that before looking at the evidence, you believe "natural reasons" has a 1 in 1 million (or some similarly large number) chance of being true. Is this correct?
Because oppression hurts real people, with real consequences. Any argument that will be used to deny people equal rights and justify mistreatment of them requires extraordinary evidence, because otherwise we end up at eugenics.
These discussions aren't theoretical; to pretend they are is actively harmful.
Further, it's not even a correct use of the Appeal to Consequences fallacy. If the natural causes hypothesis is true, it does not logically follow that anyone should be oppressed.
It does, however, logically follow from the "natural causes" hypothesis that you can't have both equal rights and equal proportions (i.e., either you discriminate against men, or you have fewer women).
All rhetoric should be looked at critically, and there's nothing wrong with being extra critical of rhetoric that's historically dubious.
What's your initial response to the phrase "separate but equal"?