My general understanding of Columbus' voyage is that he thought it was possible because he figured the earth was smaller than what people had thought it was for thousands of years. This belief was so wrong that he was ridiculed before he finally found someone to sponsor the voyage. Say what you will about him, but I doubt that Columbus was a stupid man. He must have had some "evidence" that the earth was smaller than commonly believed in order to be willing to undertake the voyage. Did he base his belief on his own measurements? Were there scientists or any other scholars who agreed with him? Was there any sort of debate about the size of the earth within the scientific community at the time, even though the 'smaller earth' camp might have been an extremely small minority? Was Columbus' belief based on scripture at all?