I'm afraid I disagree with much of what you've just said:

  > I bet you weren't confused by my text.

Actually, I was. It took a number of tries (where the number in question is strictly greater than one) to work out what you meant, and finally I had to read it aloud. I was trying to work out who or what it was that owned the "ironic", and what the ironic was that was owned.

I've just read that capitalization matters, because there's a bug difference between helping Uncle Jack off a horse, and helping Uncle jack off a horse.

  > not knowing you live on a planet is ...
  > a fundamental ignorance.

I disagree with what I think you're trying to say. For that person it's irrelevant knowledge. Consider - do you know the atomic number of strontium, or the proof of the Banach-Tarski theorem? Not knowing such things is also fundamental ignorance, but you don't care about that because you don't think it's important or relevant. Why should someone else be forced to know that the Earth is a planet, or that the Sun travels around the galaxy at about a million miles a day? Why should they know that as you travel 8km the Earth drops away by 5 meters, or that the distance to the Moon is about 284 megameters? Why should they know that light travels about 1ft/ns, or that sound travels about 1ft/ms? These are things that I consider people ignorant for not knowing, but I accept that they don't need to know them.

I also accept that others will think I'm ignorant. I'll get laughed at for not knowing the characters in a Shakespeare play, or for not know who the latest contestants are in X-Factor, or America's Top Model, or Dancing With the Stars.

I'll help people learn, and I'll explain why I think it's important, but I won't laugh at their lack of knowledge. I'll appreciate that they know things I don't, and while I might not care about those things, I won't condemn them for doing so.

And finally, there are perfectly usable physical models in which the Earth is flat. To say otherwise is to display ignorance of the context in which they are useful, more useful than the more complex spherical model, which in turn is less accurate than the oblate spheroidal model, which in turn is not as accurate as the one I use in other parts of my work.