What is a theory?

I've been meaning to blog on this very topic for a long time, but, via Pharyngula, I've found an article by Steve Olson published in The Washington Post that explains this point better than I probably could do myself. One of the most frequent canards that creationists use is that evolution is "just a theory." In fact, a lot of those idiotic warning stickers required on biology textbooks by various school districts say this very thing. The problem is, the word "theory" has a very different meaning in science from its meaning in colloquial use. But just let Olson explain:
If you want to know one reason why the debate over teaching evolution remains so contentious, consider the stickers some school boards have wanted to paste in high school biology textbooks. They label evolution a "theory, not a fact," suggesting that an alternative explanation is possible.

It's a clever strategy. Even people sympathetic to evolution often don't know how to respond to the assertion that evolution is "just a theory." And the opposite claim -- that evolution is a fact -- can generate skepticism among those who don't like to be told what to think.

But these stickers use the words "theory" and "fact" in a very misleading way. The biggest problem is that "theory" has two separate meanings. In common usage, "theory" means an idea or a hunch: "I have a theory about why she left him." No one really knows what the reasons were, but we can guess.

That's not what "theory" means within science. When scientists speak of the theory of gravitation, cell theory or evolutionary theory, they are talking about scientific concepts that have been so thoroughly tested that they are very unlikely to change. Theories are the results of decades or centuries of scientific effort. They draw on many interconnected observations and ideas. They are the end products of science, not stages on the way to the truth.

In science, a hunch or conjecture is called a hypothesis, not a theory. When Copernicus proposed in the early 16th century that the Earth revolves around the sun rather than vice versa, his idea was a hypothesis. But four centuries of observation and thinking have convinced us that heliocentrism is a theory, not just an intriguing idea. It is compatible with everything we know about the solar system and explains observations that cannot be explained in other ways.

Ideally, English would have a different word for these comprehensive organizing concepts in science. But for now, "theory" is doing double duty. So calling evolution a theory may seem to denigrate it in everyday terms, but in scientific terms that's high praise.
Precisely. The Theory of Evolution is just as rich and based in evidence as the Theory of Relativity or any of the other major theories in science, and the reason scientists won't take creationists seriously is because they challenge a well-founded and accepted theory without presenting strong evidence contradicting evolution and/or supporting their ideas. (Alties frequently do the same thing.) My only quibble with the article is that Olson doesn't really explain how old theories are usually incorporated into new theories at some level, mainly because theories by scientific definition represent the best explanations for a scientific phenomenon that presently exists. (The contrarian in me wants to use this simple observation to illustrate that the advancement of scientific knowledge is usually evolutionary, not revolutionary.) For example, the theories behind Newton's Laws of Motion were not disproven by the Theory of Relativity. Instead, Einstein showed that Newton's Laws were a special case of relativity for situations in which the velocity is much less than the speed of light, so that the factor v/c approaches zero and Einstein's equations reduce to Newton's Laws. Given that such slow velocities were all that Newton could observe in his time, he was absolutely correct to derive the laws that he did.

I agree with PZ. We should never, ever refer to creationism or intelligent design as "theories." They are not. They don't even rise to the level of hypotheses. It's also important to remember that science is not logic. Logic is an important part of the scientific method but does not necessarily have much to do with how natural phenomena operate. Many are the scientists who have been misled by an idea of how they thought nature should be, based on logic, as opposed to how nature actually IS, based on evidence and experimentation. (After all, Lamarckian evolution is a wonderfully logical concept--logical and wrong, not the way nature operates.) "Intelligent design" creationists frequently use logic (usually bad logic, but logic nonetheless) to justify their "hypotheses." However, logic alone is not enough. Science is about evidence, experimentation, hypotheses, and reasoning. They all have to be consistent with each other for a principle to be considered valid. Creationism and its deceptive offspring intelligent design fail on all these counts.


  1. As you know, I am a person of faith.
    I am an odd person of faith though.

    My feeling is ...creationism is a thing of faith. We've had the discussion off your blog on this. I won't defend faith. Faith is not tangible, nor defendable, nor can it (or should it) be put up against a scientific method. It is, a thing of the heart.

    Alties ..however, are messing with medicine, which is pure science, so it is far different.

    Here's where I differ from most of those whom I agree with on the foundation of the universe ...
    I think, we SHOULD learn about evolution. I think it is necessary. I think we MUST learn. I am not afraid of what you will tell me. Nor should anyone who is solid in their belief system be afraid of it. If you TRUELY believe in creation ...then what have you to fear of someone else's belief?

    I homeschooled my son for 2-4th grade, then 6th -8th grade. He thouroughly learned evolution. So much so, in the 9th grade biology class HE'S helping others.
    Why? Because we're strong in our belief's, and he wants to be a paleontologist and he needs to understand it.

    The fact of the matter is, as you said in the email, some Christians do believe that God set evolution in process. I'm not sure about that, but I'm also not willing to argue otherwise. Anymore than I'm willing to argue end of the world theory with fanatics that say the world is ending tomorrow.

    The more we learn, whether we agree or disagree, the more we understand, our point, or our opponants point ...and we come to an understanding, and we just might learn something. As I did when you and I discussed the term theory in an email.

    I don't understand what everone is so afraid of by letting the 'other side' know what the idea's are (ESPECIALLY the creationists letting their children learn evolution!!!!!!)

  2. I have no problem with people believing in creationism or intelligent design. I do have a problem with people trying to force it to be taught as science when it clearly is not. As you point out, it is a matter of faith, not science. If even as conservative a religious leader as Pope John Paul II can reconcile Catholic doctrine with evolution, I can't understand why these fundamentalists can't.

    Of course, some of these fundamentalists believe that the Catholic Church is heresy and the Pope is the Antichrist; so maybe that explains it partially.

  3. Oh brother ... please do not get me started on end times! (I have a husband obsessed with it and it drives me insane and he's totally off base & WRONG with it)

    First, if you read the words of Jesus, you'll know, we can't know when ...period. Trying to guess is futile.

    Second, I firmly believe that THIS Pope is a Christian & Godly man. I don't necessarily believe that because a pope is a pope that they are, but THIS one has a relationship with God and is definitly a Godly man and therefore cannot be the anti christ!

    Third, end times people are devided in pre trib(ulation), post trib, mid trib or amelinialist where they don't believe in the Rapture but they believe Christ will come and set up his Kingdom again on earth. (where they believe that Christ will come and Rapture the church)I have decided I am a Panmelinialist ...however it PANSOUT!!!

    Geesh. If I have faith in God, then why do I have to figure it out?????

    End and all it's furry gets my blood pressure up. I thouroughly enjoyed reading the Left Behind series ...just like I enjoyed reading the Robin Cook medical books and the John Grisham books.

    Do I think Revelations is prophetical? Could be, it also could be a parable or representative of something ...and JESUS is the one who set up the prescidence (sp?) for parables.

    ok, stepping off my second soap box.
    Glad my rant last night actually made it on your blog.

  4. I am a Christian medical student, and I believe that the world was created about 6000 years ago. I definitely believe that natural selection and what is often called "microevolution" are facts, but I don't believe that natural selection explains our origins. I got my undergrad degree in biology from a secular heavily-evolutionary-minded university, and I left more convinced than ever that what is commonly called "macroevolution" is false, and technically is not really a theory. I just don't see what evidence or experimentation there is to support the belief that organic molecules formed cells in a primordial goo, and that these were somehow able to develop all the intricate biochemical processes necessary for life. Most of the evidence for evolution of species can also be used to support creation (e.g. homologous traits can point to a common Creator just as well as a common ancestor). So, basically, I agree that the natural selection in regards to microevolution is a true theory, but I don't see how macroevolution can be, I think it is a hypothesis. Thoughts?

  5. First off, whenever I hear "macroevolution" and "microevolution," I know I'm dealing with creationism, not science, because biologists do not distinguish between the two. Any such distinction is highly arbitrary and artificial, as the evolutionary forces that influence bacteria can also influence multicellular organisms. It is a creationist canard that "macro"-speciation has not been observed. Second, evolutionary theory says nothing about how life originated in the first place from non-life. It only says how life evolved once formed. You are confusing abiogenesis with evolution, something creationists frequently do.





  6. As long as you've got a creationism topic up, I thought I might direct you to http://www.creationtheory.org/. I think you'll find a kindred spirit out there.

  7. it might help if you learned how to be honest. your post and comments are filled with falsehoods.

    you proclaim ""Intelligent design" creationists"- but many ID supporters are in no way creationists. how can you be a "creationist" if you have no problem with common descent?

    try to keep your lies contained to a higher level, so fewer people can point them out!

    i find it in no way shocking that you support hate-filled anti-religion bigot PZ Myers. your arrogant attitude fits well with his own.

    you claim that real scientists (aka- only those who buy into darwinism) make no distinction between micro and macro evolution. this is either ignorance or another lie (since weve alrady established the fact that youre a bald faced liar, well go with lie on this one as well). many darwinists themselves have debated whether small changed can lead to the bigger changes needed to support the model. i doubt youre unaware of these people in the camp.

    you claim that macroevolution has been observed- another falsehood. we dont even have a consensus definition of SPECIES...no new novel forms have ever been observed to come about via selection. fruit flies and e coli were all fruit flies and e coli in the end. speciation is a different matter- few can even totally agree on what truly makes a species a different species. the inability to interbreed? or this inability coupled with isolation of the species? or more? or less? theres no perfect view that all can agree on.

    so, you dont care for religion...you dont care for ID. at least try to be honest and not FILL your posts with outright lies.

  8. Yawn.

    Go back and look at the FAQs I posted. You clearly have a lot to learn about science AND manners.

    And, yes, "intelligent design" IS creationism.


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