Measured Against Reality

Tuesday, December 12, 2006

Theories, Hypotheses, and Guesses

In conversation the words theory, hypothesis, and guess are used more or less interchangeably (neglecting the fact that no one says hypothesis in conversation). This can cause some confusion about what the terms mean, leading to people saying “____ is only a theory”, with the blank most frequently being filled with “Evolution”, “Global Warming”, or some other “controversial” scientific Theory.

The problem with this is that scientists use the word theory differently than when you have a theory about who stole your lunch at work. If you have a pretty good idea that it was Joe from accounting, but what you have is a hypothesis, not a theory.

One of the differences lies in experiment. A hypothesis is often untested, but just as often it has been tested, but not enough to be considered confirmed. Once a hypothesis has been tested enough to be cautiously labeled “true” (which takes a while), then it can be called a theory.

Another difference is that a Theory is a framework, it contains the explanatory models, the equations, the predictions, and all the experimental observations and data in one unified and coherent structure.

When scientists say Theory with a capital T, the theory has been tested, it has been tested a lot, and it has been confirmed. The Theory of Evolution is not a theory in the same sense as your “theory” about who took you lunch, it has been spectacularly confirmed at every available opportunity, and no piece of data has ever been found that conflicts with it. The same is true for other capital-t Theories, like the Germ Theory of Disease, Heliocentric Theory, the Theories of Special and General Relativity, and Quantum Theory. Saying “____ is just a theory” is essentially saying that despite decades, sometimes centuries, of experimentation that has yielded piles of data that all match these theories beautifully, we should throw them out.

All that it indicates is that the speaker is a clueless hack whose opinions on scientific matters mean absolutely nothing. Speaking that phrase is tantamount to saying “Look at me! I’m an idiot!”

So next time you start to use the word theory colloquially, stop yourself and use hypothesis instead, all the cool kids are doing it. And if you ever hear someone say “____ is just a theory”, kindly explain to them why they’re full of shit.



  • I think you are right in some cases. Trotting out the phrase "x is just a theory" can be disingenuous. But it does not mean that the speaker is always "full of shit" as you say.

    You write as though Science comes with it a self-evident meta-insight as to what certain terms mean or convey that it is not necessarily available to the uninitiated "great unwashed". In doing so you are not doing science of course - you are doing epistemology. Sadly, many scientists are as woefully ignorant and incompetent at epistemology as non-scientists are "full of shit" about science!

    In the case of many people in the science business (especially what Thomas Kuhn called "normal science") the default, unreflective instinct is to adopt a naive positivism and scientism. The danger of the consequent hubris to society is very great.

    I would say it encourages the insidious idea of social engineering, it creates disrespect for religion, and it leads to a priesthood of "men in white coats".

    So I think that's what some people are getting at by the phrase "x is just a theory". Sure institutionalised science is fascinating and exciting. But when scientists lose touch with our fallibility and the impossibility of "knowledge based on foundations", then they can get a little carried away...

    By Anonymous Pali Gap, at 12:51 AM, December 13, 2006  

  • Well said pali gap.

    By Blogger Mr. Fantastic!, at 5:24 AM, December 13, 2006  

  • A theory is a variable set of conditions that produce an exact desired results. Examples: Electrical light.

    By Anonymous Anonymous, at 3:03 PM, December 13, 2006  

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