Some scientific theories that are in the way of religious, political, and corporate interests have been getting a bad rap. These theories are claimed to be false by their foes. So for example, creationist claim that evolution is false, climate change deniers claim that global warming is false, and so on. In fact, many people seem to imply that theories are ephemeral, and to buttress their claim they offer a list of theories that have been proven “false”. Why should we rely on a scientific theory to affect public policy today if it can be shown to be false tomorrow?
In addressing this issue there are several things we have to consider.
Before we begin, we need to make the clarification that the word “theory” in the popular parlance can be a synonym for a guess or a very preliminary explanation. In science, a theory is a vastly more stable form of knowledge. In fact, if the theory is sufficiently developed, it in itself can become a fact. So what are the characteristics of a sufficiently developed theory? They are:
1) It explains the existing observations and experimental results.
2) It has generated predictions that have been found to be true.
3) It has generated practical applications that work.
4) Results from other scientific disciplines corroborate the theory and the theory corroborates results in other scientific disciplines.
Please read the list above again carefully. Don’t you think that when a theory fulfils these characteristics we can say with confidence that it has clearly grasped important aspects of the realities it’s trying to explain? But, you may ask, what if a genius like an Einstein comes along and thinks up a new interpretation for everything the theory explains and predicts, and expands it into a different theory to explain new things? Can’t we say then the theory was proven false?
Well, let’s consider what Einstein did. He reinterpreted Newton’s laws of gravitation and motion, and came up with explanations for phenomena the Newtonian interpretations could not explain. Einstein thus relegated Newton’s laws to particular cases where velocities are much lower than that of the speed of light or when very strong gravitational fields are not involved. But here is the thing: the speeds at which planets, rockets, space probes, and objects in everyday life move, and their behavior in the gravitational fields that they encounter most of the time, can be described with a satisfactory level of accuracy by Newton’s laws. The existence of a planet (Neptune) and the return of a comet (Halley’s Comet) were predicted using Newton’s laws. The life of astronauts and the integrity of multimillion dollar space probes depend on the veracity of the calculations employing Newton’s Laws. Is it fair to say that Einstein proved Newton’s theories were false?
Of course not! Einstein showed Newton’s theories were incomplete, and this is what the public has to understand when discussing scientific theories. Sufficiently developed scientific theories cannot be false, they can only be incomplete. When assessing scientific theories, it is counterproductive to talk in terms of true or false. What has to be discussed is whether a theory has been formulated at a high enough level of detail, in other words, whether the theory is complete enough. We don’t need theories to be 100% true. They can’t be (nothing can), and they don’t have to be. We only need the theory to be complete enough to be useful for society.
Finally, it must be pointed out that the vast majority of scientific theories are not “big name” theories such as the theory of evolution or global warming. There are hundreds of scientific fields and subfields that have given rise to thousands of theories most of which are boring, highly technical, and devoid of importance to the “culture wars”. Therefore they do not make the news, and non-scientists are not even aware of them. Most of these theories have never been overturned, and in fact form the basis of modern science leading to tens of thousands of practical applications and policies. If these theories were not sufficiently complete representations of reality, modern life would not be possible!
So next time you are pondering the worthiness of a scientific theory, remember, it's all in the completeness.
The figure is a collage of a copy of a painting of Isaac Newton by Sir Godfrey Kneller (1689), which is in the public domain, and a photograph of Albert Einstein by Orren Jack Turner obtained from the Library of Congress, which is also in the public domain because it was published in the United States between 1923 and 1963 and the copyright was not renewed.