I recently got into a discussion on the subject of faith, and it occurred to me that when it comes to arguments between religious believers and nonbelievers, there is often a serious lack of understanding of this concept.
This is, as is very common in such instances, because there are two closely related meanings of the word. To have faith in something can simply mean that you trust it; or it can serve as a reason to believe it.* In the first case, you have a belief, in which you place your faith; in the second, you have faith, out of which you form a belief.
A scientist’s faith does impinge on her beliefs, in that her faith in her experiments is a necessary condition for her to accept their results; but that faith didn’t arise ex nihilo, out of nothing. It came from her prior beliefs, which ultimately — if she’s doing science right — came from raw observations made without preconceptions or faith in anything. (This is how science, properly done, avoids an infinite regress, but that’s a topic for another day.) For the non-questioning religion, on the other hand, the faith is supposed to come first. We might call the scientist’s faith informed faith, while the proselyte has blind faith.
The faith my wife and I have in each other is of the first sort. We trust each other to be considerate of each other’s interests, to not stray, and all the other things we promised. This is entirely reasonable; and it doesn’t mean that my trust in her is placed blindly. If either of us didn’t have good reason to believe the other would be worthy of our faith, we’d never have married in the first place. I have faith in her because I have reason to.
Science has faith in its methods and results, also precisely because it has reason to trust them: they have always worked before. They haven’t been entirely without error; but in cases of error, the methods still tell us what to do. This is a bit of a sticking point for some rationalists, especially those who grew up being taught by a religion that having faith in something (ie. God) meant not questioning it. It’s quite understandable to be uneasy about the word in this situation. But this is only because — sometimes deliberately — religious advocates blur the difference between blind and informed faith.
To be fair, most theists actually don’t have blind faith in their God; the belief itself comes from other sources. This sort of faith, in and of itself, is fine. (I think there is always an error in the processes that inform the belief itself, but that’s another separate matter.) The problem only arises when, as does sometimes happen (and disproportionately among the more vocal, argumentative believers), the cart of faith is put before the horse of belief.
*A reason to believe in this sense is not necessarily a good reason. But it’s dishonest to say that bad reasons, in terms of how people actually think, are qualitatively different from good ones.