If someone believes that the earth is flat then he automatically believes that all the pilots in the world know it (and never speak about it). That is illiterac

If someone believes that the earth is flat then he automatically believes that all the pilots in the world know it (and never speak about it). That is illiteracy to say the least. You certainly don't believe everything you read, but well established knowledge from centuries ago isn't something some lunatic came up with. So if someone dismisses gravity as a hoax, are we to support him because he is a critical thinker and start jumping off cliffs trying to fly?