Hypothesis. Theory. Law. These scientific words get bandied about regularly, yet the general public usually gets their meaning wrong.
Now, one scientist is arguing that people should do away with these misunderstood words altogether and replace them with the word "model." But those aren't the only science words that cause trouble, and simply replacing the words with others will just lead to new, widely misunderstood terms, several other scientists said.
"A word like 'theory' is a technical scientific term," said Michael Fayer, a chemist at Stanford University. "The fact that many people understand its scientific meaning incorrectly does not mean we should stop using it. It means we need better scientific education."
From "theory" to "significant," here are seven scientific words that are often misused.
The general public so widely misuses the words hypothesis, theory and law that scientists should stop using these terms, writes physicist Rhett Allain of Southeastern Louisiana University, in a blog post on Wired Science. [Amazing Science: 25 Fun Facts]
"I don't think at this point it's worth saving those words," Allain told LiveScience.
A hypothesis is a proposed explanation for something that can actually be tested. But "if you just ask anyone what a hypothesis is, they just immediately say 'educated guess,'" Allain said.
2. Just a theory?
Climate-change deniers and creationists have deployed the word "theory" to cast doubt on climate change and evolution.
"It's as though it weren't true because it's just a theory," Allain said.
That's despite the fact that an overwhelming amount of evidence supports both human-caused climate change and Darwin's theory of evolution.
Part of the problem is that the word "theory" means something very different in lay language than it does in science: A scientific theory is an explanation of some aspect of the natural world that has been substantiated through repeated experiments or testing. But to the average Jane or Joe, a theory is just an idea that lives in someone's head, rather than an explanation rooted in experiment and testing.
However, theory isn't the only science phrase that causes trouble. Even Allain's preferred term to replace hypothesis, theory and law -- "model" -- has its troubles. The word not only refers to toy cars and runway walkers, but also means different things in different scientific fields. A climate model is very different from a mathematical model, for instance.
"Scientists in different fields use these terms differently from each other," John Hawks, an anthropologist at the University of Wisconsin-Madison, wrote in an email to LiveScience. "I don't think that 'model' improves matters. It has an appearance of solidity in physics right now mainly because of the Standard Model. By contrast, in genetics and evolution, 'models' are used very differently." (The Standard Model is the dominant theory governing particle physics.)
When people don't accept human-caused climate change, the media often describes those individuals as "climate skeptics." But that may give them too much credit, Michael Mann, a climate scientist at Pennsylvania State University, wrote in an email.
"Simply denying mainstream science based on flimsy, invalid and too-often agenda-driven critiques of science is not skepticism at all. It is contrarianism ... or denial," Mann told LiveScience.
Instead, true skeptics are open to scientific evidence and are willing to evenly assess it.
"All scientists should be skeptics. True skepticism is, as [Carl] Sagan described it, the 'self-correcting machinery' of science," Mann said.
5. Nature vs. nurture
The phrase "nature versus nurture" also gives scientists a headache, because it radically simplifies a very complicated process, said Dan Kruger, an evolutionary biologist at the University of Michigan.
"This is something that modern evolutionists cringe at," Kruger told LiveScience.
Genes may influence human beings, but so, too, do epigenetic changes. These modifications alter which genes get turned on, and are both heritable and easily influenced by the environment. The environment that shapes human behavior can be anything from the chemicals a fetus is exposed to in the womb to the block a person grew up on to the type of food they ate as a child, Kruger said. All these factors interact in a messy, unpredictable way.
Another word that sets scientists' teeth on edge is "significant."
"That's a huge weasel word. Does it mean statistically significant, or does it mean important?" said Michael O'Brien, the dean of the College of Arts and Science at the University of Missouri.
In statistics, something is significant if a difference is unlikely to be due to random chance. But that may not translate into a meaningful difference, in, say, headache symptoms or IQ.
"Natural" is another bugaboo for scientists. The term has become synonymous with being virtuous, healthy or good. But not everything artificial is unhealthy, and not everything that's natural is good for you.
"Uranium is natural, and if you inject enough of it, you're going to die," Kruger said.
Natural's sibling "organic" also has a problematic meaning, he said. While organic simply means "carbon-based" to scientists, the term is now used to describe pesticide-free peaches and high-end cotton sheets, as well.
But though these words may be routinely misunderstood, the real problem, scientists say, is that people don't get rigorous science education in middle school and high school. As a result, the public doesn't understand how scientific explanations are formed, tested and accepted.
What's more, the human brain may not have evolved to intuitively understand key scientific concepts such as hypotheses or theories, Kruger said.
Most people tend to use mental shortcuts to make sense of the cacophony of information they're presented with every day.
One of those tendencies is to make a "binary distinction between something that is true in an absolute sense and something that's false or a lie," Kruger said. "With science, it's more of a continuum. We're continually building our understanding."