I mean, when you understand a concept and also its opposite then you understand all in the middle, like a scale of gray

Like Black and White and Red all over???

Isn’t it Black and White and READ all over?
....in referance to the newspaper joke??

and the deeply embarrassed zebra.

Contradiction has nothing to do with understanding the entire gamut between extremes.  Comprehension would be closer, but not really the right word.

Back decades ago there were a bunch of Black/white/read/red jokes.

And is the color GREY or GRAY?

In all due certainty, most Engl. grammarians would judiciously rank "some good/bad news" as better usage, than so with yon singular "a(n)"; but contradictory rules have always permitted this same article used correctly with other, plural nouns & adjectives such as quant. "few" in much too familiar "a few, good men": so judge not lest ye be judged!

Opposing concepts don’t have to have a middle.

For example, “I believe in God” and “I don’t believe in God” are opposing concepts. But “I’m really not sure about this God thing” is a third concept, not the middle of concepts one and two.

Nor does eating dough and nuts constitute eating doughnuts.

What about the doughnut holes? They usually come in Baker’s dozens??

Donutnut hole?!?!? Yum! where? I love those things!!!

Glazed or Sugar??
Chocolate or with Sprinkles??
—they are on saparris.

Is that Jim Bakker’s dozen? Boy, were there ever a lot of holes in that guy’s facade! And Tammy Faye always looked glazed.

Glazed, as in do-nuts? missed the implications back in April.  She looks like ‘sprinkles’ now.