This is what somebody stated in refutation to my statement on gravity. If you can't trust others, then what science are you supposed to believe?
If you want to have any chance of persuading an FE'er that they are wrong...then "appeal to authority" doesn't cut it.
Anything that cannot be directly observed - with at most simple equipment - is simply dismissed as being a part of the grand NASA/UN conspiracy.
So forget that we have photos (taken by NASA) of a clearly spherical earth...forget that we can use telescopes to clearly demonstrate that the sun and moon are not 30 miles across and 3000 miles away...forget everything that cannot EASILY be demonstrated.
Not that these aren't perfectly valid arguments...just that you won't get anywhere in talking to FE'ers about those things.
The argument about gravity is one I've recently explored here - and one problem with discussing it is that there are (at last count) FOUR different FE theories about the Earth's gravity - and a couple more about the gravity of Sun and Moon.
Earth:
1) The disk is infinite and gravity is as it is in RET. (Doesn't work because of variability of gravity at poles and equator).
2) There is no gravity. The Earth is accelerating upwards at 9.8 m/s/s. (Doesn't work because of variablilty of gravity at poles, equator and tall mountains).
3) Air pressure causes the phenomenon of objects falling and having "weight". (I can't begin to explain how insanely broken this one is! Put an object under a bell jar, pump out the air - and ask why it doesn't float around inside the jar!)...kinda/sorta explains why gravity is less on tops of mountains and absent entirely in orbiting spacecraft.
4) Some combination of (1) and (2) or (1) and (3) or (2) and (3)...makes life more complicated - but still doesn't explain pole/equator gravity changes.
Moon:
1) The moon really does have actual gravity - of course because it's small and despite being relatively close - we have to adjust the universal gravitational constant - but this is said to "explain" the tides. (Sadly, it fails because there are TWO high tides and TWO low tides every day...and without centrifugal forces due to moon's rotation around the earth - the FET explanation doesn't work).
2) The moon just attracts water and nothing else...I'm not sure that this is different to (1)...at least for common observations.
3) The moon repels water (which explains the high tide when the moon is not in the sky - but not the one when it is!)
Sun:
...well, I'm not sure how FE'ers feel about solar gravity. Since the tidal effects of the sun in "the real world" are small - but definitely measurable - in FET, it might maybe have much less gravity than the moon - despite being the same exact size and distance. Maybe it's less dense or something.
Where does this leave us?
As far as I can tell, FET is broken - there are just such an incredible number of SIMPLE daily experiences that it cannot explain. Not things that require us to trust scientists or that can be hand-waved away with "NASA-conspiracy!"...things like you standing on a beach on a crystal clear night - and watching the tide roll in at midnight with the moon nowhere in the sky. That one, SIMPLE experiment says that the world is round. It's irrefutable given FET as currently described.