Just a Theory?

We’ve all heard people say it – “oh, evolution . . . it’s just a theory!” as if evolution’s status as a theory renders its reliability as little more than a hunch or an opinion. But is this an accurate interpretation of a scientific theory’s reliability?

Image Credit: Christophe Michot, Wikimedia, CC BY-SA 3.0 “Gravity is just a theory, isn’t it?” (The BASE jumpers above are wearing parachutes,  but gravity still makes this a dangerous sport.)

Image Credit: Christophe Michot, Wikimedia Commons, CC BY-SA 3.0
“GRAVITY IS JUST A THEORY, ISN’T IT?”
(The BASE jumpers above are wearing parachutes,
but many consider this sport to be the most dangerous in the world.)

As discussed in previous posts, science is the study of nature (as well as an increasing number of human behaviors and activities) by means of an objective process involving the accumulation of physical evidence and rational explanations. Initial explanations for natural phenomena are known as hypotheses, which can range in reliability from logical, research-based explanations to total guesses. Such explanations cannot be confirmed or verified unless they are testable by means of observations and/or experiments, and until enough evidence has been gathered and analyzed to convince many different scientists of their accuracy.

“Darn . . . another hypothesis bites the dust.”

A scientific theory, on the other hand, is defined as a well-tested and verified explanation that elucidates the underlying patterns and relationships in a relatively broad range of phenomena. Thus, a theory differs from a hypothesis in a couple of important respects: (1) a hypothesis may or may not be verified, whereas a theory has always been verified; and (2) a hypothesis is an explanation for a narrow set of circumstances, while a theory explains a wider range of phenomena. Hypotheses and theories are similar in the sense that both must be able to make testable predictions, and both must be able to account for any contradictory evidence. The confirmation of a hypothesis, however, is usually just one piece of evidence in a broader picture, its primary importance often being its exposure of the next question that must be answered. A theory, on the other hand, is synthesized from a number of hypotheses and lines of evidence.

Image Credit: The Biology Corner, Evolution Concept Map, CC BY-NC 3.0 Evolution is an excellent example of a theory that is supported by many lines of evidence, including the distribution of fossils in time and space, the existence of transitional fossils, similarities in the genetic code between different species, vestigial and homologous structures  in various organisms, and the observed evolution of populations through changing environments and artificial selection.

Image Credit: The Biology Corner,
Evolution Concept Map, CC BY-NC 3.0,
Word Bank Removed
Evolution is an excellent example of a theory that is supported by
many lines of evidence, including the distribution of fossils in time and space,
the existence of transitional fossils, similarities in the genetic code
between different species, vestigial and homologous structures
in various organisms, and the observed evolution of populations
through changing environments and artificial selection.

A scientific theory, therefore, is the goal or pinnacle of scientific research, a statement of explanation that is very nearly fact . . . “very nearly” in the sense that those drops of liquid falling from a gray sky are raindrops falling from the clouds. Sure, there’s a slight possibility that your senses are deceiving you, or that the drops consist of something other than rainwater, but such possibilities are so small that you are safe in assuming that it is raining – and you are also safe in assuming that a scientific theory is correct. Thus, the word “theory” signifies something completely different in the scientific world than it does in casual conversation; in fact, the way it is used in casual conversation is far more similar to the way scientists think of an unverified hypothesis – a speculation or a guess. Which raises the question: why do so many non-scientists believe that a scientific theory is the same as a hypothesis? Well, possibly because of the following . . .

“I wonder why my friend just hung up on me . . .
I was merely suggesting that the ‘theory’ he was proposing
wasn’t actually a theory but a hypothesis.”

(1) Dictionaries typically define the word “theory” as (a) a group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena, (b) a proposed explanation whose status is still conjectural and subject to experimentation, (c) an ideal set of facts or principles, or (d) an abstract thought, conjecture, or guess. The definition in (a) is basically the same as that of a scientific theory, whereas the definitions in (b), (c), and (d) are more similar to that of a hypothesis. In fact, the word “theory” is historically derived from the Greek word, “theoria,” which was defined as an “observation.” As philosophers began to contemplate nature, however, the word “theory” was increasingly used to signify thoughtful and rational explanations for natural phenomena. And, as natural philosophy evolved into science, the word “theory” was adopted by scientists to indicate what I’ve already defined as a scientific theory. Hence, the word “theory” can be accurately applied to statements of varying degrees of certainty, with the use of the word to indicate a well-tested and verified explanation being a fairly recent development in its history.

Image Credit: Theresa Knott, Wikibooks, GNU The philosopher Aristotle’s untested “theory” that objects  twice as heavy fell twice as fast was abandoned after 2,000 years  when scientist Galileo dropped two balls of different masses  off a building (the Leaning Tower of Pisa, according to legend)  and found that they hit the ground at the same time.

Image Credit: Theresa Knott, Wikibooks, GNU
The philosopher Aristotle’s untested “theory” that objects
twice as heavy fell twice as fast was abandoned after 2,000 years,
when scientist Galileo dropped two balls of different masses
off a building (the Leaning Tower of Pisa, according to legend)
and found that they hit the ground at the same time.

(2) Science textbooks, teachers, and even certain scientists are themselves known to misuse the terms for the various types of scientific explanations. For example, many textbooks state that once a hypothesis has been confirmed by numerous experiments, it is elevated to the status of a theory. But, as I’ve already discussed, a verified hypothesis can never be elevated to anything more than part of a theory. In addition, some textbooks state that the confirmation of a theory elevates it to the status of a law. A law, however, most commonly refers to a mathematical relationship between two observable phenomena . . . it is, therefore, similar to an observation in that it doesn’t necessarily explain why such a relationship exists, and it is closer to a verified hypothesis in that it only applies under a narrow set of circumstances. Science teachers, also, are occasionally guilty of downplaying the reliability of scientific theories, mainly in order to avoid confrontations with those of their students who have religious objections to those theories. Finally, scientists themselves typically refer to certain mathematical calculations, particularly those in physics and astronomy, as “theoretical” (consistent with the “abstract” definition of theory), a description that many argue should be changed to “hypothetical” if no physical evidence has been obtained supporting such calculations.

Image Credit: Liugaila, Wikimedia Commons, CC BY-SA 3.0 A scientific law such as the one above is a description of the relationship  between energy, mass, and the speed of light –  but not an explanation of why this relationship exists.

Image Credit: Liugaila, Wikimedia Commons, CC BY-SA 3.0
The scientific law above is a description of the relationship
between energy, mass, and the speed of light –
but not an explanation of why this relationship exists.

(3) Despite a scientific theory’s high level of confirmation, this doesn’t mean that a theory cannot change. Theories are generally so complex that it’s not unusual for them to gain additional components as more evidence is accumulated, or for some of the current components to need refinement, revision, or even abandonment in favor of different components. Such openness to revision can lead those who do not fully understand the scientific process to conclude that a scientific theory is no more reliable than a casual theory or hypothesis . . . which is patently untrue. For one thing, a change to a theory is never made lightly but only in the face of evidence that has itself been verified, or in the face of a simpler, more elegant explanation. In addition, it is a strength of science rather than a weakness that theories can be changed, because if they couldn’t, theory would become dogma. And, finally, small changes in a theory do not at all contradict the fact that the basic idea of the theory is one for which little or no change is foreseen in the coming years.

Image Credit: UC Davis ChemWiki, Wikitexts, CC BY-NC-SA 3.0 US  Theories are often developed over several years of effort  on the part of many scientists. With respect to atomic theory,  the basic idea that matter consists of atoms hasn’t changed  since it attained the status of a theory, but the proposed structure  of the atom has been revised and refined many times.

Image Credit: UC Davis ChemWiki, Wikitexts,
CC BY-NC-SA 3.0 US
Theories are often developed over several years
of effort on the part of many scientists.
With respect to atomic theory, the basic idea that
matter consists of atoms hasn’t changed
since it attained the status of a theory,
but the proposed structure of the atom
has been revised and refined many times.

(4) The media . . . ah, the media. If there are a few errors in science textbooks, you can bet that the number of errors in other forms of media are far, far greater. Not only does the media call every scientist’s new discovery and possible explanation a “theory” (when, in most cases, it is a hypothesis), but it also makes little distinction between true scientific theories/hypotheses and ideas that appear scientific but are supported by little or no evidence. By the latter, I am, of course, referring to pseudoscientific topics such as creationism, homeopathy, crystal worship, astrology, UFO-ology, and psychic prediction – some of which are based on ancient pagan or religious beliefs, and others of which are either unsupported by evidence or have failed tests of their accuracy. To be fair, not every media outlet is guilty of disseminating erroneous information (technical magazines and mainstream newspapers being the least guilty of this), but for every reliable source of information, there are hundreds of books, magazines, tabloids, radio/television programs, and websites that excitedly proclaim completely false ideas with as much authority as they do truly scientific ones. Unfortunately, when such ideas are eventually discredited, many people assume that the theories espoused by scientists must be equally flimsy and untrustworthy.

Image Credit: Jonathan Wilson, Flickr, CC BY 2.0 Homeopathy is a form of alternative medicine based on the doctrine  of “like cures like,” in which a substance that causes the symptoms  of a disease in healthy people will supposedly cure similar  symptoms in sick people. The preparation of homeopathic remedies involves  repeatedly diluting a chosen substance in water or alcohol,  and the amount of this substance in the final remedy is often zero. No homeopathic remedy has ever been shown to be more effective than a placebo,  which is consistent with the lack of any biologically active substances in the remedies.

Image Credit: Jonathan Wilson, Flickr, CC BY 2.0
Homeopathy is a form of alternative medicine based on the doctrine of “like cures like,”
in which a substance that causes the symptoms of a disease in healthy people
will supposedly cure similar symptoms in sick people. The preparation of
homeopathic remedies involves repeatedly diluting a chosen substance
in water or alcohol, and the amount of this substance in the final remedy
is often zero. No homeopathic remedy has ever been shown to be
more effective than a placebo, which is consistent with the lack of
any biologically active substances in the remedies.

Given the above considerations, it is no wonder that the general public so easily confuses scientific theories with hypotheses, guesses, or hunches. And other than science educators doing their utmost to educate their students and the general public as to the differences between scientific theories and other types of theories, the only way in which to emphasize the difference is for scientists themselves to adopt another term for their most established explanations. Indeed, some scientists advocate for the word “model” to substitute for the word “theory,” and others support changing the word “theory” to “scientific fact.” I personally dislike the word “model,” if only because its definition as a “representation,” “imitation,” or “example” lends an air of unreality that I don’t believe should be associated with a scientific theory. In addition, a “scientific fact” could easily be confused with a simple “fact,” or verified observation, which again would undermine the definition of a “scientific theory.” My suggestion would be to refer to scientific theories as “scientific conclusions” . . . in that a “conclusion” is typically defined as the end of an event or process, or as a judgment or decision reached by reasoning. Scientific theories represent the culmination, if not the end, of the scientific process, they are developed through logical reasoning, and the word “conclusion” connotes a level of acceptance far greater than that accorded the word “theory” in casual conversation; hence, to my mind, the word “conclusion” is a far better substitution for “theory” than either “model” or “fact.”

Image: “Dragnet” Television Series, Wikimedia Commons, Public Domain “Just the facts, ma’am!” But what facts might those be? Simple facts or scientific facts? Observational facts or explanatory facts? Hypothetical facts or theoretical facts? So many facts, so much confusion.

Image Credit: ”Dragnet” Television Series,
Wikimedia Commons, Public Domain
“JUST THE FACTS, MA’AM!”
But what facts might those be?
Simple facts or scientific facts?
Observational facts or explanatory facts?
Hypothetical facts or theoretical facts?
So many facts, so much confusion.

Unfortunately, it is doubtful that I have enough influence to convince the scientific community to start using the word “conclusion” instead of “theory.” Thus, I must resign myself to simply reiterating that the reliability of scientific theories is completely different than that of other theories. Scientific theories represent years of work on the part of many highly trained people who have carefully analyzed a wealth of data and ruled out any other explanations for such data. Because these theories are always held open to change, they are never referred to as “proof” of any particular explanation, but they are nevertheless as valid as any verified observation we can make. A scientific theory is rather like a gemstone . . . first, it is a  “rough,” but, just as a gemstone is cut and polished to a brilliant shine, a theory is shaped and confirmed until it thoroughly illuminates the way in which a part of nature works. Once in a great while, just as a gemstone may be scratched or even crack, a theory may change due to some new methodology, discovery, or idea – but both are extremely durable, nonetheless. Scientific theories are not always correct in every minute detail, but they are the best explanations we have for understanding natural processes; and the huge number of products and technologies that have only been invented due to the knowledge gained by science is a testament to their accuracy and dependability!!

Image Credit: NASA, Wikimedia Commons, Public Domain If science were not reliable, it is highly doubtful that humans could have traveled to the moon and back!

Image Credit: NASA, Wikimedia Commons, Public Domain
If science were not reliable, it is highly doubtful that humans
could have traveled to the moon and back.
But such travels are pretty strong evidence that
science = giant leaps for mankind!