A Scientist’s Rant about the Word “Theory”

Frustrated scientist

I have many pet peeves in my life. Because I am a scientific editor, many of my pet peeves revolve around abuse of the English language. The abuse that set me off most recently is the misuse of the word “theory”. These days everyone has a theory about something. For example I have a “theory” as to why I gained five pounds over the holidays: Too much rich food and egg nog! However, from a scientific standpoint, saying “I have a theory as to why I gained five pounds over the holidays” is not a proper use of the word theory. While it is likely that the food and egg nog contributed to the weight gain, I do not have a theory. The cause of the weight gain has not been scientifically scrutinized and put through rigorous testing. There isn’t a pile of scientific evidence to support my statement. What I have is a sound working hypothesis, not a theory.

On a scale of scientific certainty, a theory shares the top spot with scientific law, then down at the bottom is hypothesis. That’s not to say that all theories or laws are 100% correct. There are cases where a scientific theory or law has needed a little tweaking. For example, everyone knows that Sir Isaac Newton “discovered” gravity supposedly after an apple fell on his head. His description of gravitational forces stood the test of time for 400 years until the 20th century, when modern scientists determined that Newton’s description of gravity seemed to unravel when applied to events inside black holes. These scientists, who include Albert Einstein and Stephen Hawking, then expanded on Newton’s ideas and revised the description of gravity so that it was consistent with the new observations. The result was a stronger, more well-supported theory.

An example where the theory might be disproved altogether: recent results at the European Organization for Nuclear Research, known as CERN, have suggested that neutrinos are capable of travelling faster than the speed of light, something that is not possible if Einstein’s theory of relativity is true. Scientists are scrambling to confirm these findings and determine if the speed of these neutrinos is the death knell for Einstein’s theory.

Anne Marie Helmenstine at About.com sums up the differences between the scientific concepts of theory, law and hypothesis. She states:

“A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true.”

“A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it.”

“A law generalizes a body of observations. At the time it is made, no exceptions have been found to a law. Scientific laws explain things, but they do not describe them. One way to tell a law and a theory apart is to ask if the description gives you a means to explain ‘why’.”

Examples of scientific theories and laws include Newton’s Three Laws of Motion, gravity, evolution and string theory.

Unfortunately, the level of scientific certainty associated with the word “theory”, as it is used outside of the lab or classroom, was low to begin with and is eroding even further. The word “theory” has become synonymous with “hypothesis”, and it makes me want to scream. I hear people say “Evolution is only a theory”, and I want to respond with “Yes, but so is cell theory, heliocentrism and even gravity. These theories have all withstood the onslaught of scientific testing and are consistent with all of the available data and observations.

I was starting to feel that I was fighting a losing battle, that the word “hypothesis” would soon go the way of the dinosaurs, at least in everyday language.

Imagine my surprise, my elation, when a recent rerun of the television show Big Bang Theory got it right. One of the nerdy, überintelligent characters on the show used the word hypothesis and used it correctly! I even pointed it out to my husband, who is also a scientist and could appreciate the source of my joy. Not long after that, I heard the word “hypothesis” used correctly on the television show Bones.

Maybe there is some hope that the word “hypothesis” isn’t dead after all.

With that glimmer of hope in my heart, I now turn to my other newest pet peeve: people using “me” as a subject by saying things like “Me and my best friend went to the library…”, but that is a rant for another day.

What is the topic of your most recent rant?

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Terri Sundquist

Terri has worked as a Scientific Communications Specialist at Promega Corporation for more than 13 years, and prior to that, spent more than 5 years solving problems and answering questions as a Promega Technical Services Scientist. She graduated with B.S. degrees in Chemistry and Biology at the University of Wisconsin—River Falls, then earned her M.S. in Molecular Biology from the Mayo Graduate School in Rochester Minnesota.


  1. I’m guessing, Michele, that Terri would not have as much cause to watch Dinosaur Train as you or I would. :)

  2. My 6-year-old loves to generate hypotheses – and her inspiration for doing so: Dinosaur Train! If a generation is growing up watching that show, there is hope yet for the proper use of “hypothesis”. Or, to put the way characters on that show might: I have a hypothesis: young viewers of the show Dinosaur Train will grow up knowing how to properly use the word “hypothesis” in everyday language, thereby keeping it from going the way of the dinosaurs.

  3. I have to admit that I have never seen an episode of Dinosaur Train, but I am not surprised that a PBS show is teaching kids the proper definition and use of the word “hypothesis”. There is a reason that PBS is my favorite TV channel.
    I love the irony in the fact that a show named “Dinosaur Train” is helping to keep the word “hypothesis” from becoming extinct.

  4. I think scientists are a huge part of this problem. As a graduate student in evolutionary biology, I constantly hear the word “theory” mis-used in classes I TA. This is done by professors on their lecture slides! As I sit in class right now, we are considering two “theories” of why organisms age and die: the “rate of life” theory and the “evolution” theory. The evidence for both is mixed and weak. They are clearly competing hypotheses! It’s not my field, but from what I know, string theory is much more of a hypothesis too.

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