What is a Theory?

by Scot Noel

What is a theory, especially a scientific theory? And how controversial can they be?

No doubt you’ve heard some authority proclaim “well, evolution is only a theory!”

Guilty as charged! If you were feeling particularly contrary, you might point out that gravity itself is only a theory, as are any and all of the many thousands theories you can find detailed in any number of books, including the Dictionary of Theories by Jennifer Bothamley.

My car operates according to the dictates of many theories and usually starts right up and gets me where I’m going. Whether I “believe” in the theories of fluid dynamics and chemical kinetics is meaningless. I can “gas and go” regardless.

What can be confusing to some is that a theory need be neither “right” nor “wrong,” nor is it a fact. Instead, facts (observable properties and effects) are the building blocks of most good theories.

But it isn’t so complicated either. All of us can understand how theories work in our everyday lives.

Perhaps you know someone who is a gossip. That they are indeed a gossip we will take to be an observable fact. Based on this fact, you develop a “theory” that if you tell the gossip something about Mrs. X and the Mailman, the news will make it all over town.

Your insight into how a fact or facts can be used to both explain observed events and predict future behavior is a theory. In this case, it is a “theory of mind.”

Whether your theory is useful or not depends on how well it works for you and others, how reliable it is in allowing everyone to both understand and control the situation. In our example, if the news did not spread the way you believed it would, your theory would be rather useless to you. If it failed to predict what would happen, real life events may force you to reevaluate the nature of your “fact” and your theory. (Perhaps the gossip is not such a gossip after all.)

…no doubt, conceptualization will be altered from age to age, as experience is broadened, and the complete truth may perhaps never be attained Jöns Jacob Berzelius

The Best Definition of Theory I Know Of

In 1818, a Swedish chemist named Berzelius wrote down the best definition of a theory I’ve ever come across. It goes like this:

“All our theory is but a means of consistently conceptualizing the inward processes of phenomena, and it is presumable and adequate when all scientifically known facts can be deduced from it.

“This mode of conceptualization can equally well be false and, unfortunately, presumably is so frequently.  Even though at a certain period in the development of science, it may match the purpose just as well as a true theory.

“Experience is augmented, facts appear which do not agree with it, and one is forced to go in search of a new mode of conceptualization with which these facts can be accommodated; and in this manner, no doubt, conceptualization will be altered from age to age, as experience is broadened, and the complete truth may perhaps never be attained.

“But even if the goal can never be reached, let us never abandon our endeavor to come closer to it.”

The Earth Centered Universe

Let’s take a more complex example of theories. In this case, good observation and painstaking math allowed one theory to supplant another, but only after centuries of study.

Back when the absence of city lights allowed us to observe the night sky, way back when you could see the stars at night, men noticed something. They noted how the stars moved with the seasons and how the constellations appeared differently in different hemispheres. They charted the movement of wandering stars and called them “planets.” These facts, combined with the obvious stability of the ground beneath their feet and the oft observed rising and setting of the sun, led to the theory of an Earth-centered universe.

We know this today as Ptolemaic Cosmology. Claudius Ptolemaeus was a citizen of Roman Egypt who lived in the second century A.D. and whose theories of an Earth centered universe were not the ramblings of a foolish man. No indeed. An accomplished mathematician, Ptolemy’s great work, known as the Almagest, was based on hundreds of years of information, tradition, and observation.

And his theory worked! For hundreds of years, the mathematics of Ptolemy’s system allowed the prediction of planetary movements, gave astronomers the power to calculate the positions of the sun, moon, and stars, as well as foretell astronomical events like eclipses. Ptolemy’s theory still works today! Why then do we no longer accept the notion of the Earth as the center of everything?

Because continued observation showed that while some facts fit under certain conditions, other observations did not. Certain predictions did not work. Though powerful, the theory was not the best theory available. People tried to make it work for centuries, to figure out why it seemed to work most of the time but then failed to jive with certain observable facts of planetary movement.

Along came Nicolas Copernicus in 1543 with the “Revolutions of the Celestial Spheres,” a theory putting the sun at the center of the universe. Johannes Kepler weighed in on the idea soon after and 67 years later Galileo Galilei would use his primitive telescope to observe moons circling the planet Jupiter. The math of planetary movement which developed from these observations became extraordinarily powerful, especially once Isaac Newton offered (around 1693) his Universal Law of Gravitation. The “theory of gravity” had given humanity enormous capability. Though it would have to wait another 275 years before we had the machines to go to the moon, the math was good enough, even then.

Certainly long before July 20, 1969, no one could argue that the Earth was the center of the universe. The facts were clear.

But it wasn’t that way at first. Both Copernicus and Galileo had their run-ins with organized religion. For many, any sense of the Earth as only a satellite was a direct threat to the sense of a “God Made” world. Though fourteenth century folk didn’t call it “Intelligent Design,” in a sense that’s what they were defending. After all, didn’t the Bible clearly say that Joshua commanded “Sun, stand still over Gibeon; and Moon, in the Valley of Aijalon.” How could it be that it was the Earth was moving?

But the Earth does move around the sun, and as it turns out even the sun is not the center of the universe. Consider for a moment that a grain of sand on a typical beach may have more weight on that beach than Earth does in its own galaxy, let alone the 80 some billion galaxies the Hubble telescope can see. (Yes, our Earth is a tiny little rock orbiting a tiny little corner of nowhere.)

And if you believe in God, and your ancestors believed in God, and you want your children to believe in God, guess what? None of these changing theories did much to make a dent in what appears to be a fairly immutable and indomitable fact of human nature – that we tend to have such beliefs. Acknowledging the unavoidable, the now easily observable fact that the Earth is not the center of the universe did nothing to prove or disprove the nature of God, people just had to adjust to a new and clearly observable reality.

So whether a theory is controversial, or challenges our religious beliefs, is not a measure of its meaning or usefulness. As we’ve seen, the power of a theory is in its ability to describe the world to us in a useful way, even ways that can take us to the moon or allow us to understand a universe which, through many means of observation and factual analysis, is trying to tell us that it is at least 13.7 billion years old.

Bad Theories

What is a bad theory? Bad theories fail to describe the world around us; they offer theses which ultimately have no power to predict what will happen next, or even lead us off in the wrong direction entirely.

Before germ theory, the nature of illness and ideas about how disease was spread ranged from the displeasure of the gods to mysterious vapors and unpleasant odors. None of those theories gave us the power to cure infection, inoculate against viruses, or perform the miracle of more than doubling human life span since the year 1,000 A.D. Ultimately, however strange it may have seemed that little unseen organisms could make us sick, it was germ theory that revolutionized medicine and health.

Even in modern times, bad theories have caused enormous damage. In the Soviet Union of the 1940s all geneticists were banished, some even executed, because the political hierarchy favored the theoretical views of Trofim Lysenko, a politically connected agronomist whose theories of agriculture and inherited traits had found great favor. But ideology is no substitute for “what works in the real world.” Lysenko’s bad theories helped spread famine, death, and an ignorance which held back Soviet biology for more than a generation.

In the end, ideology had to give way. Even the most hidebound belief cannot stand against the might of a useful theory.

Do Theories Reveal the Truth?

Do theories speak to us about the nature of reality? Now you’re venturing into philosophical territory and you can pick your own answer all the way from “yes” to “no” and even “it’s really not that important.”

For example, the nature of light can be described both by a theory of particles and by theory of waves. Which is really true? They both are. When light hits a mirror, it bounces off like a particle. But light also bends and refracts as if it were a wave. On one level, both theories are mutually exclusive, so which one is right? Again, both are. The math involved with both theories allows for powerful understanding and prediction of the behavior of light.

Remember, it’s utility, not dogma, ideology, or belief that tests a theory. It is what is shown to work in the real world and can be confirmed by other, independent minds. And that’s the wonderful thing about theories – how open they are to challenge, revision, and perfection, even from one generation to the next.

As to the truth, that slippery concept may be beyond us. We are, after all, only human. But developing the theories that could take us to the stars, give us practical immortality, and design the first generation of intelligent machines – that’s probably well within our grasp. Just wait and see.


In this article, I have touched on evolution as a kind of live wire to spark my discussion of theory and the controversy of theories. Though the science of evolution is well-founded and rational, in some minds it strikes to the heart of deeply held beliefs, and for those individuals no amount of data or proving can be enough. For them, the very notion of relating man to the rest of the animal kingdom offers only an abyss as dark as any abomination imaginable.

So it was, I imagine, for many when Earth stopped being the center around which the sun was commanded to spin.

But evolution is not based on ideology; nor is it deeply flawed. It has gone as far beyond Darwin as the Apollo program rose above the first ideas of Copernicus. Today evolution is based on detailed observations of living organisms, the fossil record, and an understanding of the mechanisms of genetics.

We can’t hybridize plants and livestock for generations, modify genes in the lab for decades, and be -as we are- on the verge of creating new species artificially, only to claim that none of this really takes place in nature.

It is true that evolutionary biologists struggle and debate over whether this mechanism or that, this timeline or that, best describes the process. Of course they do. That is called science. That is the nature of all good theories. Even our understanding of cosmology continues to undergo changes, but just as in cosmology it is impossible to go back to an Earth centered universe, so in biology it is impossible to step back from the solid foundation of understanding that, like it or not, life evolves.

The scientists aren’t trying to be dogmatic or anti-religious. Richard Feynman, the Nobel winning physicist, said it best. “The only way to have real success in science… is to describe the evidence very carefully without regard to the way you feel it should be.”

It is by finding more and more accurate and refined theories that reflect and explain observable properties and effects that science has produced our amazing progress over the last few centuries.

Is There a Theory of God?

Not that I’m aware of.

It seems to me that science cannot describe God. It can only describe, in limited but useful fashion, nature.

Even the theory of evolution is not a refutation of a Creator. It is an observation about how the world works in the nuts and bolts of physical reality. It may offer us a way to see past some of our own naïve ideas about ultimate reality, but it cannot touch on the truth of an ultimate reality beyond science. You’re going to have to decide that one for your self.

We are, after all, only human. Some concepts are no doubt beyond our ability to comprehend. Perhaps that is why we work at religion in metaphor and parable, and in ancient stories that were never meant to be history or science (in the modern sense, history and science did not even exist when the many tales of Genesis and the first man and the first woman came to be.)

We have, after all, only our all too human brain to think with, and it is a thing of nature. Where our cousins the chimpanzees can count a little; we can number the stars. But that is a long way from understanding everything.

An ultimate mind unfettered by human limitations needs no theories of how it all works, but certainly comprehends as a part of its own being the fabric of existence. And in that existence lie faith and fact together, theory and belief as a part of one coherent reality.

Only we set theory and belief at odds with one another. Remember, light can be understood as both a particle and a wave. In different experiments both are true. In what way –simply beyond human understanding—are both faith and theories like evolution equally valid? If it is all beyond human understanding, we will never know.

But there are innumerable things we can know. That is what science is all about. So however controversial any one scientific thesis may be when seemingly in conflict with traditions of faith, politics, and ideology, we turn our backs on theoretical science at the peril of our own existence.

That’s worth repeating in bold: we turn our backs on theoretical science at the peril of our own existence.

The Earth does circle the sun; germs do cause disease; physical traits are inherited through genetic transmission and not environmental factors, and, yes, life evolves.

These things we know. They are solid theories proven by time, experiment, and observation. Neither “right” nor “wrong,” they remain as true as anything we have the ability to understand. They provide powerful insights into the way the world works and how we can afford ourselves ever greater control over it. We know these theories will be refined over time, in ways that more and more closely reflect the observable properties and effects of the real world.

And if we do not understand the rest –how it all fits in with the faith of our fathers– well, that’s the really hard stuff anyway. But one thing I feel must be certain: if it is to be worth anything, faith must be about more than being stubborn once the facts are in.

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