When someone defends the concept of the flat earth. I've often heard the argument being made that "I trust my eyes". But we know that our eyes can deceive us. If they couldn't magicians and illusionists wouldn't have careers. In fact, everything that we do perceive visually comes into our eyes upsidedown, backwards, and full of holes. It's our brains that do the hard work of constructing that into what we would call vision. Why would you rely on something as fallible and subjective as visual perception and reject the more precise and reliable forms of measurement to make your argument?