The scientific method is a potentiation of common sense, exercised with a specially firm determination not to persist in error if any exertion of hand or mind can deliver us from it.
So it sounds that this method doesn't care much about error or who makes the mistake, but what is the meaning of "deliver" in this context? What does "it" refer to?
This is quoted from Peter Medawar.
In this context phrase "deliver somebody from something" means "to save somebody from something", while "it" refers to "error". So in another words it says that "scientific method makes every effort to avoid an error".
Deliver can be used figuratively to mean "remove X from Y where Y is an undesirable state or situation." I think this comes from the religious phrase deliver us from evil but does not have to have a religious connotation specifically when used figuratively.
It, therefore, refers to error, since that's the "undesirable state" that the "scientific method" can "deliver" us from.
"Deliver" To avoid humans from altering the correct outcome of scientific fact. Ex. To deliver biologist from altering the natural course of nature inorder to preserve the true findings of an experimental outcome as much as humanly possible. "It" refering to the scientist and their instictive innabilty to not know the true final outcome if they exert their actions and thought proccesses in more than just a miniscule manner.
