"Science is based on facts" is a nonsensical statement. Science is a method by which one tries to establish facts. The problem is that it is a process run by

"Science is based on facts" is a nonsensical statement. Science is a method by which one tries to establish facts. The problem is that it is a process run by humans which have biases. Bias can influence many things in science, not least of which is hypothesis selection. Through no fault of their own, scientists who have beliefs may not come up with hypotheses that contradict them, and therefore fail to test them. They will select the better of the two hypotheses they have, but they may miss something. This is a flaw in the scientific process that goes way beyond bias, by the way. It's the part that not anyone can do: that requires creative thinking, and is limited by it. To emulate Churchill, science is the worst way to discover truth, except for all those other ways that have been tried from time to time.