The Misconception
The word “theory” is defined in the Oxford English Dictionary as the “conceptual basis of a subject or area of study (1);” meanwhile, in Merriam-Webster you’ll find the definition to be “the analysis of a set of facts in their relation to one another (2).” I’m sure that some people will be confused by these definitions, as the word “theory” has a very different meaning in colloquial speech. It’s quite common to hear someone say, “I don’t know, but I have a theory.” In this context, the word theory is nothing more than a synonym for “hunch”, “supposition”, or “speculation”. These words fail to inspire faith in the speaker. If your doctor told you that they had a “hunch” that prescribing you antibiotics would kill the bacteria making you sick and cure your illness, would you trust them? How about if your lawyer (whom you pay $100 per hour) said that they “suppose” you have a chance at winning your case?
What if your science professor taught you about the “theory” of evolution?
Nobody likes ambiguity when they’re looking for answers, whether that answer is something as simple as the weather forecast for the day, or something as complex as the foundation of a particular field of study. The problem with the word “theory” is that it inspires ambiguity because of the way we hear it used in daily speech. In the scientific community, we have a tendency to use the dictionary definitions of words while ignoring the way that those words are used by the general public. Of course, this has a tendency to cause confusion and it means that we, as scientists, often accidentally miscommunicate our ideas to nonscientists.
The Truth
Let’s examine the dictionary definitions of “theory” that I presented above. As Oxford succinctly puts it, a theory is a central idea which an entire field of study (whether it be philosophy, science or art) is built around. I hope that it’s easy to see the distinction between this definition and our colloquial “hunch” used for the word “theory”. If a theory were in fact just a guess, then it would not be a central pillar holding up an entire body of study and literature. The next definition of “theory”, from Merriam-Webster, is perhaps a little trickier to understand, but really gets at how “theory” works in the scientific community. A scientific theory is a conglomeration of many ideas which have been tested over and over, support each other, and in some way all point to the same logical outcome or conclusion. This conclusion, of course, becomes a scientific theory.
Very rarely do you hear everyday people describe scientific statements as “theory.” What I typically hear (and I’m guessing this is true of all of us), is an individual say “Scientists have proven X” or “It’s a scientific fact that X is true.” These statements confuse people even further. And do you know why? Get ready for this one because it’s about to rock your world…
Science doesn’t prove things. In fact, it attempts to disprove things.
I believe that this is best illustrated with an example, particularly an example given to me by a professor at MU to help me understand this concept. Let’s say that you’re an ornithologist (someone who studies birds). And you make the claim that every crow in the world is black. That’s not an unreasonable guess – most people expect crows to be black. So in order to test your hunch you begin traveling the world and recording the color of every crow in sight. After 50 years of study you’ve seen most of the crows estimated to be alive in the world and every single one of them is just as you had expected – black. Does this prove that you're correct? Does this prove that every crow in the world is black?
After your travels and extensive study, you’ve settled down and started teaching courses at the University of Missouri, one of the best schools in the country (Biased? Me? No.), and one day a student of yours walks into your office fresh off a plane from his winter vacation in Massachusetts. He hands you his camera, excited to show you its contents, and you see it is filled with pictures that he took of crows while on his travels.
One of the crows is white. One.
And just like that, 50 years’ worth of work goes up in flames, because you've been proven wrong.
Science doesn’t attempt to prove things. And for this reason, science doesn’t prove things. The things we study are not “facts” or “truths” or “proofs”. They’re theories, supported by hypotheses.
Well what about Hypotheses?
In the scientific vernacular that most of us learned in middle school, these ideas which support theories are called hypotheses. Ideally, science is about observing the world around us and coming up with ways to explain it which are consistent and therefore apply universally to all instances of a particular event. In order to explain the things we observe, we come up with a hypothesis, or a guess (you could even say a “hunch”) that we think might explain what we have seen.
A hypothesis, however is not a completely random guess, it’s a guess that we make based on observations and hypotheses made by other scientists. Further, a hypothesis is a guess which we can test scientifically, and, most importantly, a guess that we can disprove. Remember, in science we always seek to disprove ourselves. This means that science never carries the burden of proof, per se. Rather, scientists hold the responsibility to exhaustively test their hypotheses, and the hypotheses of others, in an effort to prove them wrong. If, time and time again, we are unable to prove that a particular hypothesis is wrong, then it can be used as evidence to support a scientific theory. Generally, many tested hypotheses are grouped together in support of one theory.
But… But there are laws, right?
Well, what about laws then? Most of remember hearing about the Laws of Thermodynamics, and probably thought that this term “law” sounded pretty definite. Why don’t our groups of tested hypotheses become laws instead of theories? The terms “law” and “theory” in science have very different meanings. In fact, theories contain a lot more information than laws; a law is a statement about a concept, while a theory is an explanation of a concept. If we were asking questions, a law would be the answer to the “what” and a theory would answer the “who, when, where, and how.” Laws and theories are far from one and the same, and, contrary to popular misconception, a theory can never be elevated to a law (or vice versa).
In Conclusion
The takeaway from this explanation is basic: In science, nothing is EVER “just a theory.” So forget the way that the word theory is used in everyday speech. When you learn about a scientific theory you are learning about an idea which is extremely well supported by a huge amount of research that has been scrutinized over and over and over again, and that has never been disproven. Generally speaking, a theory is the absolute best explanation that the scientific community has for an observed phenomenon and it is not to be taken lightly. Remember that though some theories are controversial to the public (like our friend, the Theory of Evolution), many other theories are taken for granted by people every day (such as Gravitational Theory and the Germ Theory of Disease).
References:
1. "Theory, n." OED Online. Oxford University Press, December 2016. Web. 24 January 2017.
2. "Theory." Merriam-Webster.com. Merriam-Webster, n.d. Web. 24 Jan. 2017.
