Some time ago, a commenter to this blog sent me a private email expressing this view:

Have you ever noticed people say “Do you believe in evolution?” just as you would ask “Do you believe in God?” as if both schools of thought have equal footing? I respect others’ religious beliefs as I realize I cannot disprove God just as anyone cannot prove His existence, but given the amount of evidence for evolution, shouldn’t we insist on asking “Do you accept evolution?”

It may just be semantics, but I feel that the latter wording carries an implied affirmation just as “Do you accept that 2+2=4?” carries a different meaning than “Do you believe 2+2=4?”

I guess the point I’m trying to make is that by stating something as a belief, it opens the debate to the possibility that something is untrue. While this may fine for discussions of religion, shouldn’t the scientific community be more insistent that a theory well supported by physical evidence, such as evolution, is not up for debate?

It’s a good point. To be fair, scientists themselves are partly responsible for this confusion because we also say that we “believe” in this or that scientific theory, and one cannot blame the general public from picking up on that terminology. What is important to realize, though, is that the word ‘believe’ is being used by scientists in a different sense from the way it is used in religion.

The late and deeply lamented Douglas Adams, author of The Hitchhiker’s Guide to the Galaxy, who called himself a “radical atheist” puts it nicely (thanks to onegoodmove):

First of all I do not believe-that-there-is-not-a-god. I don’t see what belief has got to do with it. I believe or don’t believe my four-year old daughter when she tells me that she didn’t make that mess on the floor. I believe in justice and fair play (though I don’t know exactly how we achieve them, other than by continually trying against all possible odds of success). I also believe that England should enter the European Monetary Union. I am not remotely enough of an economist to argue the issue vigorously with someone who is, but what little I do know, reinforced with a hefty dollop of gut feeling, strongly suggests to me that it’s the right course. I could very easily turn out to be wrong, and I know that. These seem to me to be legitimate uses for the word believe. As a carapace for the protection of irrational notions from legitimate questions, however, I think that the word has a lot of mischief to answer for. So, I do not believe-that-there-is-no-god. I am, however, convinced that there is no god, which is a totally different stance. . .

There is such a thing as the burden of proof, and in the case of god, as in the case of the composition of the moon, this has shifted radically. God used to be the best explanation we’d got, and we’ve now got vastly better ones. God is no longer an explanation of anything, but has instead become something that would itself need an insurmountable amount of explaining…

Well, in history, even though the understanding of events, of cause and effect, is a matter of interpretation, and even though interpretation is in many ways a matter of opinion, nevertheless those opinions and interpretations are honed to within an inch of their lives in the withering crossfire of argument and counterargument, and those that are still standing are then subjected to a whole new round of challenges of fact and logic from the next generation of historians – and so on. All opinions are not equal. Some are a very great more robust, sophisticated and well supported in logic and argument than others.

When someone says that they believe in god, they mean that they believe something in the absence of, or even counter to, the evidence, and even to reason and logic. When scientists say they believe a particular theory, they mean that they believe that theory because of the evidence and reason and logic, and the more evidence there is, and the better the reasoning behind it, the more strongly they believe it. Scientists use the word ‘belief’ the way Adams says, as a kind of synonym for ‘convinced,’ because we know that no scientific theory can be proven with 100% certainty and so we have to accept things even in the face of this remaining doubt. But the word ‘believe’ definitely does not carry the same meaning in the two contexts.

This can lead to the generation of confusion as warned by the commenter but what can we do about it? One option is, as was suggested, to use different words, with scientists avoiding use of the word ‘believe.’ I would have agreed with this some years ago but I am becoming increasingly doubtful that we can control the way that words are used.

For example, there was a time when I used to be on a crusade against the erroneous use of the word ‘unique’. The Oxford English Dictionary is pretty clear about what this word means:

• Of which there is only one; one and no other; single, sole, solitary.
• That is or forms the only one of its kind; having no like or equal; standing alone in comparison with others, freq. by reason of superior excellence; unequalled, unparalleled, unrivalled.
• Formed or consisting of one or a single thing
• A thing of which there is only one example, copy, or specimen; esp., in early use, a coin or medal of this class.
• A thing, fact, or circumstance which by reason of exceptional or special qualities stands alone and is without equal or parallel in its kind.

It means, in short, one of a kind, so something is either unique or it is not. There are no in-betweens. And yet, you often find people saying things like “quite unique” or “very unique” or “almost unique.” I used to try and correct this but have given up. Clearly, people in general think that unique means something like “rare” and I don’t know that we can ever change this even if we all become annoying pedants, correcting people all the time, avoided at parties because of our pursuit of linguistic purity.

Some battles, such as with the word unique are, I believe, lost for good and I expect the OED to add the new meaning of ‘rare’ some time in the near future. It is a pity because then we would then be left with no word with the unique meaning of ‘unique’, but there we are. We would have to say something like ‘absolutely unique’ to convey the meaning once reserved for just ‘unique.’

In science too we often use words with precise operational meanings while the same words are used in everyday language with much looser meanings. For example, in physics the word ‘velocity’ is defined operationally by the situation when you have an object moving along a ruler and, at two points along its motion, you take ruler readings and clock readings, where the clocks are located at the points where the ruler readings are taken, and have been previously synchronized. Then the velocity of the moving object is the number you get when you take the difference between the two ruler readings and divide by the difference between the two clock readings.

Most people (especially sports commentators) have no idea of this precise meaning when they use the word velocity in everyday language, and often use the word synonymously with speed or, even worse, acceleration, although those concepts have different operational meanings. Even students who have taken physics courses find it hard to use the word in its strict operational sense.

Take, for another example, the word ‘theory’. By now, as a result of the intelligent design creationism (IDC) controversy, everyone should be aware that the way this word is used by scientists is quite different from its everyday use. In science, a theory is a powerful explanatory construct. Science depends crucially on its theories because they are the things that give it is predictive power. “There is nothing so practical as a good theory” as Kurt Lewin famously said. But in everyday language, the word theory is used as meaning ‘not factual,’ something that can be false or ignored.

I don’t think that we can solve this problem by putting constraints on how words can be used. English is a wonderful language precisely because it grows and evolves and trying to fix the meanings of words too rigidly would perhaps be stultifying. I now think that we need to change our tactics.

I think that once the meanings of words enter mainstream consciousness we will not be successful in trying to restrict their meanings beyond their generally accepted usage. What we can do is to make people aware that all words have varying meanings depending on the context, and that scientific and other academic contexts tend to require very precise meanings in order to minimize ambiguity.

Heidi Cool has a nice entry where she talks about the importance of being aware of when you are using specialized vocabulary, and the need to know your audience when speaking or writing, so that some of the pitfalls arising from the imprecise use of words can be avoided.

We have to realize though that despite our best efforts, we can never be sure that the meaning that we intend to convey by our words is the same as the meaning constructed in the minds of the reader or listener. Words always contain an inherent ambiguity that allows the ideas expressed by them to be interpreted differently.

I used to be surprised when people read the stuff I wrote and got a different meaning than I had intended. No longer. I now realize that there is always some residual ambiguity in words that cannot be overcome. While we can and should strive for maximum precision, we can never be totally unambiguous.

I agree with philosopher Karl Popper when he said, “It is impossible to speak in such a way that you cannot be misunderstood.” The best we can hope for is to have some sort or negotiated consensus on the meanings of ideas.