Scientific Theories
At times I speak “loosely” and quickly to make a point. For example, I have said things like, “My theory predicts that this chair will turn purple. Wait for it. Okay, it didn’t happen. So my theory has been falsified.” Such examples are useful to make a basic point about falsification. But they can also be misleading, so I must be careful to explain what a “theory” really is.
A theory is never just a single prediction, such as that a chair will turn purple. Such a prediction actually results from a whole body of particular beliefs about the nature of reality, current states of affairs, and the sorts of mechanisms that could impinge upon things like the color of a chair. So, when I say something like, “My theory predicts that this chair will turn purple,” that is really shorthand for this whole body of beliefs that inform such a prediction, for example:
1) Lighting affects the perceived color of a chair.
2) The chair’s current color is a result of it being seen under white light.
3) I believe that a maintenance worker is about to change the lighting to black light for the purpose of an upcoming event that will take place in our venue.
4) I believe that the timing of that change will be just about when I am making my point about chair color.
5) I believe that the change to black light will make the perceived color of the chair change to purple.
And so on.
So, when I say that the failure of the color change falsifies my “theory,” what I am really saying is much more than that the failure falsified my prediction! Of course and obviously my prediction was false. The point of falsification is its power to demonstrate as false the beliefs and presumptions about reality that motivated me to make the prediction in the first place. Something about my listed five points (or even more that went unmentioned) went astray when the chair did not turn purple in timely fashion. And this fact is the jumping off point to describe in more detail what a “theory” even is.
Necessary Components of Theories
A theory must be a coherent, logically-related set of beliefs. A mere list of “facts” is not a theory, because nothing ties the “facts” together. Thus, nothing gives the list of “facts” any predictive power. For example, it is no “theory” to simply list: “The sky is blue. There are some clouds. I have a smart phone. Bachelors are unmarried men. Two plus two equals four. And some music really moves me.” All of these claims are true, but nothing ties them together into a coherent “world view” of any sort. These are instead mere “observations,” if you will. An actual theory must do more than just list facts. It must somehow tie them together.
A theory must tie facts together in terms of an explanatory account that explicates some mechanism or principle. If I say, “The sky is blue and there are clouds for the same reason, and that reason is the water vapor in the air,” now I am getting much closer to an actual theory. The more principles and/or mechanisms can be brought under one rubric, the more powerful and “theoretical” a theory is.
A theory must make predictions that emerge from the stated mechanisms/principles. Another critical distinction between theories and mere lists of observations is that theories have predictive power! Even beyond the point made in the previous paragraph, a theory is much more “theoretical” and powerful if it adds to the above by saying, “Because of the suspended water vapor, we will see rainbows when the sun is at such and such an angle, because that water vapor will have an effect like a prism.”
The predictions must inform us about implications about nature that we would not expect to discover in the absence of the theory. This is the basis of what makes science appear so powerful and productive! When theories predict results that work, we stand amazed. We sense that we would have less power in the world without the productive power of such theories.
Now, as Feynman rightly noted, the entities, principles, mechanisms and predictions of science must be definite! The vaguer and less well-defined such elements of a “theory” are, the less we will call the set of “beliefs” an actual theory.
This striving toward the definite is one thing that sets scientific theories apart from “theories” that are not really science. Not only do scientific theories posit entities and mechanisms, but they do so in definite fashion. Again, we can contrast, say, astrology from science. Astrology makes vague claims about “planetary energies” without saying what these “energies” are really like and how they work. And it then makes vague “predictions” about how these energies will affect people born during certain times of the year (again without any account of a mechanism of how/why there are any connections). So, everything is vagueness, including predictions like, “Taurus: today you will be a low energy point, so you should not seek to start any new relationships today.” Such “predictions” or advice cannot be falsified, because, instead, everywhere you look (if you are a believer) you instead see verifications of the “correctness” of the (vague) prediction!
That is a far cry from a definite scientific theory making definite predictions. And most scientific theories are far further toward the “definite” end of the continuum than the “vague” end of the continuum.
So, a good scientific theory is a content-laden, coherent, predictive set of beliefs that are definite and that make definite predictions. These, then, can be in principle falsified as definite predictions can definitely fail. This is the ideal.