The cast iron arguement as to whether or not we should believe what others say, has always been the same. If you have not actually seen somthing with your very own , unafected eyes, You should not believe. Buttheir are indirect ways of seeing/knowing. Scietists do this. And one sholuld sometime add possible credibillity to things others say if they add up partially, or perhaps partially believe. But, yes the cast iron belief will only be 100% credible if seen with ypour own eyes.