The term "theory" is used very differently by scientists in a scientific framework, as opposed to how it's used by everyone else

The other day I participated in an interesting classroom discussion about the word "theory" and how it differs from other terms like "idea", "comment" and "law". What does "theory" actually mean? The phrase "conspiracy theory" suggests a bit of a screwball element, but is this fair? Or just convenient?

The word "theory" can and does create misunderstandings. Regarding the issue of climate change, the term "theory" is used very differently by scientists in a scientific framework, as opposed to how it's used by everyone else. Every field has its own jargon, and this is commonly misused by people outside of that field. For example, if someone says they weigh 70kgs, you and I would interpret that to mean what the scales say when that person stands on them. But a scientist would interpret that information differently. They'd say that the person has a mass of 70kg which, when multiplied by 9.81 m/s2 (which is the Earth's standard acceleration due to gravity) gives that person's weight in Newtons. Therefore, the person weighs 687 Newtons. (Confused yet?)

My point? The problem with the term "theory" is how people use it.

Someone might have a "theory" that life is like a box of chocolates. Someone else might have a "theory" that aliens are coming down to earth to draw really cool crop circles just to annoy us. A third person might have a "theory" that climate change is caused not by human activity but by solar flares. Technically these are not theories at all. Certainly not in scientific terms. At the most, these are comments, and ones that aren't backed up by facts.

A theory, on the other hand, is an explanation that fits all the known facts.

Let's start with a simple fact. Maybe it's a piece of data from an experiment. But what does the fact actually mean?

This is the basic problem, because the "fact" could be the result of an error. Or a false reading. Or because someone stuffed up. In science, this is why an experiment is repeated, often multiple times. It's just to get more data to make sense of the "fact". It's for clarity.

Now you need to find a theory that explains all the known facts. Some people tend to trim their data to make it fit their theory, which is the wrong way around. Often, people will choose the experiment that provides data that only fits their theory. This is why scientists have a peer review process - they present their data and people can recreate their experiments to prove or disprove their work.

Ever heard the curious term "Occam's Razor"? It's a principle used in logic and problem-solving. It states that when confronted with different competing hypotheses, the one with the fewest assumptions should be selected. In other words, the one that explains all the facts in the simplest way. For example, if you hear the beat of approaching hooves on the ground, think horses, rather than zebras.

Therefore, as you carry out more experiments and get more data, you can start to remove the theories that suddenly don't fit with the known facts. This way you will end up with the one theory (or several) that fits all the available data.

But how is a "theory" different to a "law" (as in the "Law of Gravity")? Simply put, a theory is an explanation that fits all the known facts; a law is a proven analytical formula.

Climate change due to carbon emissions caused by human activity is also a theory. It keeps changing a bit round the edges as new data comes in. Most of this research is new, and more research is still being undertaken in fields never considered before.

In other words, a theory is something that evolves naturally. You want scientists to change their thinking as new data comes in.