BBC Newsnight on evolution: Mind your language, and don’t say “theory” unless you mean it

“Evolution is a theory”, said BBC pundit Jeremy Paxman last night[1] to Alice Roberts, and when Prof Roberts tried to explain that it was only a theory like the motion of the Earth is a theory, he interrupted her to say that the motion[2] of the Earth is an empirical fact. Well, as Prof Roberts was finally allowed to say, evolution is also an empirical fact. So for facts’ sake, let’s stop calling it a theory.

I’ve said this before and I’ll say it again. There’s a war on between those who want to preserve our scientific heritage, and those who dismiss it as “materialism” and want to replace it with a view that they themselves call theocentric. These enemies of enlightenment are not stupid or wicked. They understandably want to preserve our reverence for human uniqueness, and misguidedly imagine that the only way to do this is to deny the indelible stamp of our lowly origin. For this reason, they will go to great lengths to misunderstand the science that tells us our real place in Nature, and to call the fact of evolution a “theory” is to invite just such willful misunderstanding.

In common language a theory always involves speculation and uncertainty. In academic discourse, it means a coherent set of ideas that explain the facts. Calling something a theory in this sense tells you nothing at all about how certain it is. A theory can be wrong (phlogiston theory), known to be approximate from the outset (ideal gas theory), very close to the truth but since improved on (Newton’s theory of planetary motions), or as certain as human knowledge ever can be (number theory in mathematics). Of course you can explain all this, but you should not put yourself in such a vulnerable position in the first place. It wastes time in debate, or in the classroom. It puts you on the defensive, and thus, paradoxically, confers legitimacy on the attack. It allows the focus to shift from what we know about the world to the words we use to talk about it. This takes us away from science to the domain of the philosophers, lawyers, and expositors of Scripture who are fighting on behalf of Creationism.

And so it distracts from what you should be talking about, namely the facts. Evolution, whether we mean changes in the genetic make-up of populations over time, or the common descent of living things on earth, is a fact. It is supported by, and explains, innumerable more specific facts concerning the fossil record, molecular phylogeny (the same kind of evidence that is used every day in DNA paternity tests), the frozen-in historical accidents of organs that have lost or changed their function, the distribution of species throughout space and time, and much more besides. Creationism cannot explain these, or any of the other facts of evolution science, except by appeal to the mysterious ways of the Creator.

Nor should we ever say that we “believe in” evolution. Believing always carries with it the feeling that disbelief is an option. Some members of the jury believe the witness, others don’t. Some people believe that Hillary Clinton will be the next President of the United States, but no one would say they “believe” that Barak Obama is the current incumbent, because no sane person doubts it. I don’t “believe in” atoms, or gravity, or quantum mechanics, because I regard them as established beyond dispute, although our notions about them will no doubt continue to change as we learn more. And exactly the same is true of evolution.

Should we ever refer to the “theory” of evolution? Yes, but not when we mean the fact that evolution occurs. There is a theory of evolution, but it is not what Jeremy Paxton seems to imagine it is. Genetic change and common descent are known facts, as well established from the fossil and molecular records as the order of England’s kings and queens is from the historical records. Mutation is a fact. There are theories (interlocking sets of ideas) about just how evolution happens. Natural selection operating on existing variation is a theory, so is neutral drift, so is punctuated equilibrium, and all of these are subsumed into the present-day theory of population genetics, the foundations of which were set in place in the 1920s, before we even knew the nature of the genetic material. All this and more goes to make up the modern theory of evolution.

So yes, there is a theory of evolution, but in the same way that there is a theory of chemical bonding. It is a theory about how it happens, not if. To take an analogy from chemistry, the quantum mechanical theory of bonding is about how atoms stick together to make molecules, not if. If someone were to deny that matter is in fact made out of atoms sticking together, we would regard them as ignorant, or perverse, or strangely misled, and the same is true of anyone who denies that we share a common ancestor with chimpanzees and bonobos.

Does it matter? Yes, it matters enormously. Creationists often maintain that evolution and Creation are both beliefs, whose respective advocates differ, not about observable facts, but about how those facts are to be interpreted. And they contrast evolution, as “only” a theory, with facts or even with scientific laws, in order to claim that it is far from certain and that views refuted over a century ago still deserve a hearing.

We should not, ourselves, be using words that help them do this.

Part of this post appeared earlier this year, here, but Paxton’s tactics give it new context and relevance, and my suggestion about when we should refer to the “theory” of evolution is as far as I know completely new.

[1] Newsnight, 16 June 2014; the sector on the teaching of evolution starts 29 minutes into the programme.

[2] Actually, he spoke of its roundness, but let that pass.