I read an example of the term "ipso facto" in Merriam Webster Dictionaries which was:
If we refuse to tolerate bigotry, do we become, ipso facto, as intolerant as those whom we condemn.
I think there should have been "not" after "do" in the example. I suppose that the example's speaker is asking this for a kind of confirmatiom, meaning that if we refuse to tolerate bigotry, then there remains no difference between us and them. Am I right?
The example is grammatically correct as written.
These have the same basic meaning. Only the shade (Definition) of meaning is different.
Do I look good?
Do I not look good?
The first one is understood as a more "neutral" question.
The second one is understood to mean that the person asking believes the underlying statement is true: "I look good."
The same thing applies with questions written without "do":
Am I being helpful?
Am I not being helpful?
And
Is he here?
Is he not here?
They are functionally equivalent. In a written essay (article), the word "not" is optional. Since the dictionary is using an arbitrary example, you don't know if the speaker believes the underlying statement to be true, so it could be "do not" or "do": either is correct.
