Scientific Facts – Do They Change?

Today I watched an episode of the BBC’s brilliant series “QI” called “Knowledge“. In it Stephen Fry made an astonishing claim:

Things we know – or think we know – will be untrue in a number of years’ time.

Jo Brand added this:

There’s no such thing as a fact.

In my opinion those are very misleading statements.

First of all, they make the mistake of using a very wide definition of the word “fact”:

  • Scientific Facts
  • Assumptions
  • Hypotheses
  • Deductions

The example which they gave in the episode was the answer to the question “how many moons does the earth have?”, which used to be “one”, but changed to “two” in the first series of QI because a second – very small – moon was discovered in the 1990s, then changed to “three” because a third moon was discovered, and now to “18,000” because that many very small objects orbiting earth were discovered, and since these are called “mini moons”, that’s that. My point is that using this example to show that scientific facts change over time is a misrepresentation of science. It’s a scientific fact that the earth has a moon – which we call THE moon. This scientific fact still stands, no matter how many more moons were discovered later, or how the definition of moons was changed. If the Pluto discussion is any indication, the “mini moons” will not be considered to be “proper” moons, not because they’re below a certain arbitrary size, but because they have not cleared their orbits.

So do scientific facts change? Yes, some do. My contention is that in every such case it was not a proper fact in that it wasn’t secured by empiric evidence, meaning experiments which are independently verified. This is especially happening in areas of scientific research where experiments are difficult and/or expensive to conduct, and there is a lot of pressure on the scientists to produce results. An obvious example of such areas is medical research, and an example of a blatantly false scientific “fact” which was changed is the cholesterol/saturated fat scare that was started in the 1980s. As it turns out, the connection between those nutrients and heart disease was never based on empirical evidence, but in essence assumed from a flawed observational study done in the 1970s (Ancel Keys’ Seven Countries Study).

Of course the primary problem with calling such assumptions “facts” is that people take action on them and potentially cause great harm, the secondary problem could be even more serious: People lose confidence in the scientific process. And well they should, if it is executed so sloppily. I can only hope that not only the scientists themselves, but also people reporting on scientific findings, from bloggers and news writers to television show masters, take more care not to use the word “fact” inappropriately.

In closing, allow me to modify Stephen’s statement a little bit:

Many things which we stated without empirical verification will be untrue in a number of years’ time.

And Jo’s statement:

There’s a big difference between a proper scientific fact and mere assumptions or deductions uttered by people with or without academic credentials. The former have never been shown to change, of the latter many change all the time.

If anybody disagrees, by all means let me know – please provide me with an example of an empirically verified fact which was later found to be false.


7 thoughts on “Scientific Facts – Do They Change?

  1. I agree with your sentiment here. It is clear that something should only be stated as scientific fact to the public, once it has been verified, checked and peer-reviewed.

    However, I think the example you use confuses the issue. It’s not the case that we initially stated there is one moon, because we didn’t know about all the other debris orbiting the Earth i.e. because our scientific data was wrong. We did know all that debris was there, but it didn’t fall into the scientific definition of a moon at the time. If the scientific definition changes, the number of moons that meet that definition can change. We don’t need to add, change or edit any scientific knowledge to change a definition (although changes in knowledge may certainly trigger this change).

    Its important to realise the distinction between changing a scientific definition or scientific criteria and changing previously expressed facts based on updated scientific evidence. Even if the 2 are not always entirely decoupled.

    1. I agree completely, sometimes scientific definitions change, and that’s mistakenly reported as a change of scientific fact. However, I didn’t choose the example of the moon – the QI staff did. You rightly point out though that I conflate two different things: a) Real mistakes in science when scientists announce findings as scientific fact which somehow make it through peer-review and are then debunked years, decades or centuries later (quite rare) and b) claims which get confused with scientific fact by laypeople (much more frequent).

  2. Yep 🙂 I definitely agree with your sentiment though. It’s a big issue in science communication. Science communicators are not held to the same rigours as scientists themselves, and confusion can arise. I’m writing a post now entitled: “Who should speak about science: Scientists or science communicators. Maybe you’ll find it interesting. I’m sure i’ll certainly create an opinion after the appropriate research! 🙂

    1. Absolutely! The curious thing about Rich is that he made the Phillips head screw haircut jokes several times in different episodes – but then again Alan Davies did the same with the “leopards eat rotten meat, cheetahs only fresh” remark. 😉

      1. I can’t castigate them for that. I’m a science stand-up comedian and it’s much easier to recycle jokes than sit and think up new one 😉

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