You Keep On Using That Word. I Do Not Think It Means What You Think It Means

This blog is usually about education, but this post is only going to touch on that tangentially.  It's just something I've noticed a lot lately.  It's about a word we use often, but we almost always use it incorrectly.  That word is "theory."

When I teach my 8th graders about Kinetic Theory, the notion that everything is made of atoms, they ask why it hasn't been proven yet after all these years.  It has, of course, but they believe theory means unproven.  And they aren't the only ones.  People use the word theory frequently when they mean speculation or hypothesis.  They say things like "My theory is . . ." and then guess about the cause of a situation.  When someone talks about something that could but has not yet happened, they'll say, "It is theoretically possible to . . . "  

This is not what theory means, y'all.  This may be the fault of elementary school science textbooks.  For some reason, when we teach young children the scientific method, we teach them that we start with a hypothesis and that after some experimental support, it becomes a theory.  Then, after lots and lots of proving, a theory may grow up one day to become a law.  This is wrong, but for some reason, the authors of elementary school textbooks want to give middle and high school science teachers something to unteach.  For some readers, this may be the first time you have heard that it isn't true.

So, what is true?  What is the difference between theory and law?  A theory is an explanation of a phenomenon.  A law is a mathematical expression of a physical relationship.  There are two theories of gravity (Newton's idea of instant communication of force and Einstein's understanding of the warping of spacetime), but the law of gravity remains unchanged.

Charles' Law describes the relationship between the volume and temperature of a contained gas at constant pressure.  It is a law because it can be expressed mathematically, but when I explain to my 8th graders the changes in molecular motion during a temperature change that lead to the change in volume, I am explaining the theory behind the law.  

If you aren't a scientist, you may be wondering why this matters.  There are a number of things, after all, that don't matter when used incorrectly in everyday usage.  When you put your hand on ice and describe it as cold, you are technically wrong because there is no such thing as cold. The feeling you are describing is the flow of heat away from your hand.  While technically wrong, I don't advise students to change the way they speak in everyday language because you'll sound like a fruitcake if you go outside in the winter and say, "Brr. It's less hot out here."  The same goes for describing the suction of a vacuum cleaner.  So why does it matter with the word theory?

As a Bible-believing Christian who also teaches science, I've watched a number of debates between Creationists and Evolutionists.  There are many important ideas to be debated between these two camps, but I cringe when a Creationist says, "Well, yours is just a theory too, so you can't prove what you are saying."  It doesn't matter what valid points he makes after that sentence because he has shown his lack of understanding.  If we are going to argue in good faith, we owe it to ourselves to speak accurately.  This comes up on social media frequently as well, with people asserting "just a theory" on everything from climate to vaccines to genetics.  While it is right and good to examine the flaws in scientific methodology and examine potential bias, none of that will be taken seriously if you call something "just a theory."

If we can't be bothered to speak precisely, we should not speak at all.