The words faith and belief obviously have a natural home in religious discussions. Should scientists avoid using such words, as in statements like ‘”I believe in the theory of evolution” or “I have faith in the law of gravity”, since that seems to put them on a par with “I have faith/believe in god” and enables religionists to claim that scientific theories are similar to religious beliefs? In a recent comments section, a recurring suggestion came up that in order to avoid this misapprehension, we should avoid use of the words belief and faith altogether in scientific discussions.
I disagree with this suggestion for two reasons, one practical and the other somewhat philosophical. The practical reason is that language use tends to be anarchic and is impossible to police. People use language any way they want and indeed that is its source of much of its vibrancy, with new words and usages coming into being all the time as people break existing rules. Witness how hard it is to prevent the new usage of words and phrases that actually have the opposite of their original meanings. The word ‘literal’ is now sometimes used to mean ‘figurative’, the word ‘finite’ is used to mean non-zero or not infinitesimally small when it technically means ‘not infinite’, and the phrase ‘could care less’ is increasingly used as equivalent to ‘couldn’t care less’. There are those who fight valiantly against what they see as these signs of the abuse and corruption of language but they seem to be losing.
Hence asking anybody, including the scientific community, to refrain from using perfectly functional words such as faith and belief in scientific discourse is an exercise in futility, especially since such usage is nowhere near as egregious an abuse of meaning as the examples I gave above.
This brings me to the philosophical objection to trying to restrict their use, which is that the words belief and faith have multiple meanings depending on the context and have their place in science as well. It would be a mistake to concede perfectly functional words to religious people.
We know that it is impossible to prove a scientific proposition to be true. At best we have a preponderance of evidence in favor of it. If I release a rock in the air, it will fall to the ground and I ascribe that behavior to the law of gravity. If I repeat the drop a hundred times, the rock will fall to the ground each time. But that still does not prove that it will do so the very next time I try it. (This is the well-known problem of induction.) But I have every reason to believe that it will do so the next time and this is what is meant by saying that I have faith in the laws of gravity. In fact, I did not repeat the dropping exercise one hundred times but just said it. I did not drop it even once, so sure was I of the outcome. Readers would have thought I was crazy if I had told them that had carried through this exercise just so that I had evidence to back up my statement. When I quote this example to religious people, they too do not question the premise that the same result will obtain however many times it is repeated. And yet, we cannot say that the law of gravity is 100 % proven. We only believe that it is true and have faith that the rock will fall again.
In that sense, I am using the words faith and belief in the same sense that religious people use it, as saying that I have total confidence in its correctness even in the absence of absolute certainty. And we need to have that sense of certainty. If I had doubts about the established laws of science continuing to hold in all situations, I would be unable to function, just like those who have doubts about the laws of fluid mechanics avoid flying in airplanes. I need to be certain that when I open the faucet, the water will flow down into the sink and not spray all over the kitchen and ceiling, so that I can do it without thinking. Life would be a nightmare without our faith in the infallibility of scientific laws.
But there is a big difference between scientific faith and religious faith. Scientific faith is what enables us to bridge the small gap between near certainty (based on a preponderance of reliable and predictable empirical evidence) and certainty. Religious faith is what enables people to bridge the huge gap between unbelief (due to the lack of reliable and predictable evidence) and certainty. In the case of science, we try to make the gap to be crossed by faith as small as possible, though we can never eliminate it. If the gap starts getting bigger due to the appearance of anomalous evidence, that is a cause for concern. It is not a virtue to cling to certainty when the gap increases.
Contrast this with religious faith. There it is considered a virtue to hold on to certainty, especially when the gap is large and getting larger. Those in the religious world who believe in a god despite the lack of evidence in favor are praised for their faith, whereas in the scientific world those who believe in some theory despite the lack of evidence are viewed with concern. When a tragedy strikes innocent people, which should be considered clear evidence against a good god, people are praised for continuing to believe, even though the gap has now got larger.
What we should realize is that people learn to ascribe meaning to words not only on the basis of their strict dictionary meanings but also on the context. As a result of repeated usage, there is now usually no problem in understanding what people mean when they use ‘literally’ or ‘finite’ or ‘could care less’ in everyday conversation and writing. We should aim to achieve the same level of contextual understanding of the words faith and belief too. So rather than avoid the use of those words in science, we should use them freely and when people question us about it, take that as an opportunity to explain the difference between scientific faith and religious faith, between scientific belief and religious belief.
Hence when I give talks to students about how being scientific is incompatible with believing in any form of the supernatural, there are always some clever students in the audience who pick up on my use of the words faith and belief and argue that this implies that even I implicitly think that religion and science are similar knowledge structures. I use that as an opportunity to discuss the difference and I think that those discussions really help to advance their understanding of the nature of the scientific enterprise. I think the outcome is better than if I had avoided those words altogether.