How many times have you heard someone dismiss science they don’t believe in by saying “Oh, it’s just a theory”?

It’s an easy claim to make. The problem is the colloquial meaning of theory contrasts with the scientific meaning of the word.

What is a scientific theory?

In colloquial use, we often use the word theory to describe a guess that lacks evidence to back it up.

In direct opposition, a scientific theory is an organized set of facts, that explain a facet of the natural world that repeated experiment or observation has proven.

Any additional evidence must be consistent with the theory. If this is not the case, the theory is either revised or discarded.

Why does the difference between the two even matter?

There is nothing inherently wrong with the disparate meanings of colloquial and scientific theory. After all, the beauty of language is that it’s elastic – a reflection of constant advances in knowledge.

The beauty of science is that, like language, it never remains static. It always evolves. It allows for new evidence to prove or disprove theories.

Recognising the difference between colloquial and scientific theory means understanding that constant updating of scientific knowledge is science’s greatest strength.

The more experiments that support a theory, the more observations a theory predicts, the facts it explains - the stronger the theory.

And that’s a lot better than taking an unsubstantiated guess.