[olh]

Flat earth theory is all about humans not being able to do a specific 2d to 3d mapping using the natural brain circuitry/architecture/pathway we gained from evolution for this operation because the earth is too big for our brains/senses as an object viewed from nearby (like from a plane in the atmosphere) and we never encountered something with such measures and relationships (like a circular path that becomes linear to our senses) in the natural world we evolved. Some of us know the earth is not flat because we developed other ways (other brain circuitry) to do the mapping: some think it terms of pure geometry, some scale down earth to a ball and compare our senses to it, some think in terms of planetary movements, some use the moon to help with the mapping from our vision, etc.

[derekp7]

I always just assumed that flat earth theory is some elaborate inside joke, that the practitioners all "get", and are collectively trolling everyone else. Somewhat like the illuminati theorists, etc. If you think about it, it takes quite a bit of effort to form a valid sounding debate on a topic that you don't believe in. And it is also fun coming up with defenses on either "side".

So here's a good one I came up with for the "round earth" side. The sun is always about the size of a dime held at arm's length, at sunrise, noon, or sunset. If there earth were flat, then the sun would appear larger at sunrise, smaller at sunset, when in New York, and it would be just the opposite (smaller at sunrise, larger at sunset) when in San Francisco.

[pjc50]

No, it's much worse than that; it's a variant of the conspiracism disease, the belief that everyone else is lying about it while being unable to confront evidence.

[jimsmart]

All of that, plus a lack of understanding regarding the basics of astrophysics, it would seem. (e.g. I've seriously heard flat-earthers argue 'how can water stick to the surface of a ball?')

[flukus]

From what I've seen on youtube you're right, the one thing they all seem to have in common is that the have no understanding of gravity. Everything else seems to be an elaborate set of logical contortions to overcome this lack of understanding.