“It’s Just a Theory”

How many times have you found yourself in a discussion with someone who doesn’t believe in, for example, evolution, the Moon landings or something else we all just take for granted, something we all just know. You point out what you think is obvious about, say, evolution, only to be met with “Ah yes, but it’s only a theory!”. I’ve recently had run-ins with people who didn’t believe in various things we all take as given and I too have met the “It’s only a theory” argument so I thought I’d take a look at what we mean by a theory and what we mean by the scientific method. This is the simple version without maths and error analysis and stuff but I hope it will explain the basic ideas.

So let’s start with the basics. “What is science?” What I mean is what makes science and the scientific method different from a discussion in the pub or on FaceBook etc? Okay, if you ask me what the Moon is made of I can think for a bit and come to the conclusion that it is made of green cheese.


What has happened here? Well we have a phenomena, the Moon, which requires an explanation. I have looked at the data we have, what does it look like etc, and built up a model that explains this phenomena. This is my hypothesis but unless I can prove conclusively that the Moon is indeed made of green cheese then it will remain no more than my hypothesis. Okay, I can’t go to the Moon and take some cheese back with me


so I’ll have to use other methods like spectroscopy for example which would show that the Moon was made of the same chemicals as green cheese. This does not necessarily mean that it is made of green cheese, the chemicals could be arranged differently to make something else, so now I go to the laboratory and try to find out what else I can make with these chemicals and if something else gives a result that looks like the Moon.

So maybe I find that the chemicals in green cheese give three things that look a lot like the Moon so I have to find out which one it is. As Sherlock Holmes said:


So we do some tests and find that two of the other things cannot exist at the temperatures we have measured for the Moon so the only thing left is green cheese.

Now this is a rather silly example I know, but it does illustrate the process by which we test a model to see if it really can explain the phenomena we are observing. We now have a model that explains what the Moon might be made of and some test results that seem to confirm this model and this is the nub of the matter. We have a model that is backed up by tests and observations. And even this is not enough to make my green cheese hypothesis completely convincing. Anyone can “fix” tests and observations to support their claims, or they can select the tests and observations they quote and only use the positive ones, a trick called “Cherry Picking” where you only take the positive evidence and ignore the negative.


This doesn’t cut it in the scientific community, results have to be verifiable, that is they have to be repeatable by other, independent researchers. So you have to be able to say that if anyone else looks into this and does the same tests they will get the same results and it has to make predictions that can be tested and confirmed in real life.

So now we have a model that explains what the Moon is, a hypothesis, which can be tested by others and which, if correct, will be confirmed by their results. In fact the greatest test of all is when others try to prove you wrong but come up with the same results as you did. It is only when such a hypothesis has been tested many, many times and confirmed as good as 100% that it earns the title of “Theory” and that basically means that it is as good as true unless some very good evidence comes along that proves it wrong or improves it in some way.

Scientists always publish the raw data they have used and include error margins and discussions of possible errors so others can see that they have been thorough in their work. New ideas and discoveries are published not so that the discoverer can bathe in glory, but so others can test their ideas to see if they can be confirmed. So the scientific process looks something like this:


So basically, if something has been checked and tested and confirmed time and time and time again, then we call it a theory. If something has been liked time and time again on Facebook, then it is no more than something that has been liked on Facebook. Quoting what somebody has said doesn’t help either because that’s just quoting someone else’s opinion, that’s not evidence. And using a load of sciency sounding words isn’t proof either, that’s, well that’s just using a load of Sciency sounding words.


So don’t just accept something because it sounds like it might be right or because it kind of fits in with some other things you believe, check it out, find out how the author has checked it out. Find out who else has checked it out and how. And if you question a real scientist-


using real data and real arguments you will receive respect and counter arguments with real data If, on the other hand, you only get abuse and accusations then you are almost certainly dealing with a guy in a tinfoil hat-


The core principle of science is to question what you are told, believe nothing, to demand hard evidence.

“Just a theory”? Ok-


Here endeth todays rant. Hope you enjoyed it.



3 thoughts on ““It’s Just a Theory”

  1. As Brian Koberlein said in one of his podcasts “Flying in a plane has supported by “just a theory”, aerodynamics, and it could be wrong, but I don’t think you are willing to bet your life and the life of your kids on it”

    Liked by 1 person

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