Occam's Razor
Occam's Razor asks us which explanation makes the least number of assumptions. The explanation which makes the least number of assumptions is the simplest explanation. Occam's Razor works in favor of the Flat Earth Theory. Several examples exist below.
What's the simplest explanation; that my experience of existing upon a plane wherever I go and whatever I do is a massive illusion, that my eyes are constantly deceiving me and that I am actually looking at the enormous sphere of the earth spinning through space at tens of thousands of miles an hour, whirling in perpetual epicycles around the universe; or is the simplest explanation that my eyes are not playing tricks on me and that the earth is exactly as it appears?
What's the simplest explanation; that NASA has successfully designed and invented never before seen rocket technologies from scratch which can accelerate 100 tons of matter to an escape velocity of 7 miles per second, and that NASA can do the impossible on a daily basis, explore the solar system, and constantly wow the nation by landing a man on the moon and sending robots to mars; or is the simplest explanation that they really can't do all of that stuff?
When I walk off the edge of a three foot drop off and go into free fall while observing the surface of the earth carefully the earth appears to accelerate up towards me. What's the simplest explanation; that there exists hypothetical undiscovered Graviton particles emanating from the earth which accelerates my body towards the surface through unexplained quantum effects; or is the simplest explanation that this mysterious and highly theoretical mechanism does not exist and the earth has just accelerated upwards towards me exactly as I've observed?
What's the simplest explanation; that when I look up and see the sun slowly move across the sky over the course of the day, that the globe earth is spinning at over a thousand miles per hour - faster than the speed of sound at the equator - despite me being unable able to feel this centripetal acceleration, or is the simplest explanation that the sun itself is just moving across the sky exactly as I have observed?
What's the simplest explanation; that the sun, moon, and stars are enormous bodies of unimaginable mass, size, and distances which represent frontiers to a vast and infinite unknowable universe teeming with alien worlds, black holes, quasars and nebulae, and phenomena only conceivable in science fiction; or is the simplest explanation that the universe isn't so large or unknown and when we look up at the stars we are just looking at small points of light in the sky exactly they appear to be?