They are skeptical to everything that they cannot empirically observe themselves, and would claim that electromagnetism is something they can see for themselves, i.e. by building simple motors and batteries. Note that they might not believe in Maxwell’s equations - the experiments establishing that might be considered an appeal to authority.
Starting with their arguments is fine. Their model would have to include things like the distance to the Sun, whether or not there is a shroud around the Sun which allows it to only shine on part of the flat Earth at one time. . . stuff like that. I have found that when they lay their cards out on the table it is its own refutation.
The replies I gave aren’t wiggle room, they’re just flat out (no pun intended) denial of empirically observed reality the Flat-Earthers can see for themselves. There’s nothing more to say when the woo-mongers just reply with a “NUH-UH!”.
Ask them why Dish TV works with a fixed antenna pointing skyward. If they say the signals come from weather balloons (I actually had one nutter claim that) ask them for evidence of these TV transmitters. Ask them to show you evidence of the cell towers in the ocean.
It’s pretty easy to back the woo-mongers into a corner where denial is all they have left.
Exactly, showing that their model refutes itself because it in one way or another contradicts either itself or other things they believe in is the only way that I found that really “sticks”. I was never successful in converting a Flat-Earther by taking things that they do not believe (such as NASA photos) and saying that their model contradicts that. Thus my point that it is necessary to launch the arguments from a common ground.
I am sure someone could get a collection together and send a group of Flat Earthers to the other side of the globe. Then they could call each other when it is high noon for one of the groups. Their refusal to do these simple experiments is quite telling.
I found that these types of arguments do not work. They still have what I call a wiggle room by claiming that there are balloons or buoys in the middle of the ocean. They don’t have evidence but this does not faze them. It is consistent with their view that there is a global conspiracy that hides evidence for these balloons.
The arguments that I found work is something more along this line:
Again, this is also assuming that you have the initiative in the debate. Often these debates start with them rattling off their arguments that we have to respond. It is important to be well informed of them so that we can refute them clearly and quickly.
Note that in such a debate, the audience often see you as representations of mainstream science. If you cannot answer even one question, they conclude that mainstream science have holes in them and are not to be trusted. It is a very hypocritical position given that they often cannot answer your own objections to the Flat-Earth model, but in the business of trying to convince Flat-Earthers this is the reality.
If I have a lot of money I would fund a reality show with this premise. Episode 2 would be sending them across the “ice wall” in Antartica, and episode 3 perhaps giving them a seat in Elon Musk’s spaceship.
The FE’ers that crack me up are the ones who think the sun is just a few thousand miles up in the sky. At least they are being somewhat consistent since this is about where the Sun would need to be in order to solve some of the problems in an FE model. In this experiment you measure the diameter of the Sun at a few points that are 50 to 100 miles apart. Simple trigonometry tells you the Sun should have significantly different diameters at these points . . . but will they do the experiment? Of course not.
This problem is exactly the timezone problem that would be exposed if we send a group of them on the other side of the globe and make them call each other at noon. If you allow the Sun to be only a few thousand miles up and small enough, their model can explain why the two groups have noons at different times. Of course there are issues but I don’t want to get too much into it.
They would claim that the magnification due to atmospheric refraction can take that into account. This is an example of when one can interject. If they believe this that means that they believe in some aspects of mainstream electromagnetism and continuum dynamics. One can then show from these things that they purportedly believe that one cannot get a magnification that causes the size of the Sun to be constant.
RE: Common Ground Vs WOO Science
There is a common error I see in online debates, where the scientifically-inclined person will bring forth a mirad of scientific argument to try to dispel the woo. This is usually the wrong response, because it presumes there was a scientific argument behind the woo in the first place. DON’T DO THAT, because it only validates the hidden assumption of scientific woo. Instead, question the assumptions and examine the consequences until the contradictions start showing up. Make the Woo-er defend their own woo.
What do you mean by scientific argument? At least for the Flat-Earth case, it is difficult to do this:
Without some sort of scientific argument. In the previous example I mentioned to @T_aquaticus, the contradiction appears because the Flat-Earthers believe in both some aspects of electromagnetism and a constant angular diameter Sun. Both of these are scientific premises.
I mean, not accept the tacit premise that there is a scientific justification for a flat Earth, or that the Earth is only 6000 years old, etc… I’m short of time just now, but I’ll try to add more later.