Should Flat-Earthers be debated or ignored?

[Fake Messiah]

OK, since there are no flat earthers on this forum (or more likely they are afraid to admit they are) I've found some stuff that they consider to be evidence of Earth being flat, so maybe you can practice debunking it so that when you meet with an actual flat earther. So let's say you meet with this one, how do you respond?

Jon McIntyre was troubled by the evidence of the flat earth and simply could not bring himself to accept that such a massive conspiracy to hide the very nature of the earth could exist. He came up with an ingenious way to determine, once and for all, whether the earth was a sphere or flat. He concluded that if the earth were flat then two equally high mountains separated by many miles would appear to the observer to be the same height if the observer was stationed at a vantage point that was equal in height to the peak of the two mountaintops.
All he needed to do was to move perpendicular to the alignment of the mountains, thus creating a parallax between the mountains, and he could then see both mountains side-by-side. If, however, the earth were a globe, then the more distant mountaintop would drop below the height of the nearer mountain top by thedistance in miles squared multiplied by eight inches (miles^2 × 8 inches = distance of drop on the supposed spherical earth).
McIntyre searched and found three mountains that met his criteria. The three mountains were found in the Black Mountain Range in North Carolina. He positioned himself with his camera at an elevation of 5,385 feet on the ridge of Tennent Mountain. He then trained his camera at Fryingpan Mountain, six (6) miles in the distance from his position on the ridge at Tennent Mountain. The peak of Fryingpan Mountain has an elevation of approximately 5,380 feet above sea level. Thirty four (34) miles beyond Fryingpan Mountain was Graybeard Mountain, with an elevation of approximately 5,395 feet.



If the earth were a globe, then the curvature of the earth would cause Graybeard Mountain to drop 770 feet and be out ofthe sight of the observer. But that is not what we see.