[Editor's Note: This article was adapted from a 5-part series originally published on Evolution News & Views. The original 5 parts can be seen here: Part 1, Part 2, Part 3, Part 4, Part 5.]
"The Darwinist claim that 'theory' is always and exclusively used by scientists to mean a verified and well-established explanation is a fiction invented by Darwinists seeking grounds to scold as ignorant those Darwin-skeptics who call evolution 'just a theory.'"
Many members of the general public who are skeptics of Darwinian evolution are intelligent people with a decent understanding of some of the scientific weaknesses with neo-Darwinian evolution. In fact, a recent article in The Scientist suggests that, "public discontent with classical evolution as an inclusive theory stems partly from an intuitive appreciation of its limits." (Eric Smith, "Before Darwin," The Scientist, June 2008:32-38.) But in this highly nuanced debate, such Darwin-skeptics must avoid semantic land mines if they are to accurately, clearly, and effectively communicate their views. Some people who oppose neo-Darwinian evolution are fond of calling evolution "only a theory" or "just a theory, but not a fact." After using such a phrase, they are immediately scolded by Darwinists, who tell them that "a theory" is a "well-substantiated scientific explanation of some aspect of the natural world" and that evolution should be considered "both fact and theory."
Ken Miller just wrote a book titled, "Only a theory," basically opposing people who use such an argument. Similarly, an opinion article recently condescended:
One of the greatest misconceptions about evolution is embedded in the misuse of the word 'theory' in its application to science. The common antecedents that result in this misuse of the word are manifested in either genuine ignorance, or disguised ignorance. People are either genuinely mistaken of the word's intent, or they are well aware of the word's scientific definition, but still use the nonscientific definition in an effort to spawn doubt. … Evolution, because it's a theory, is a higher form of knowledge than a fact.
Additionally, earlier this year the NCSE's Glenn Branch co-wrote an article in an evolution-education journal taking the condescending approach: it labeled those who use the "evolution is 'just a theory' line as being "pejorative" and favorably cited a Darwinist who scolded, "To claim that evolution is ‘just a theory’ is to reveal both a profound ignorance of modern biological knowledge and a deep misunderstanding of the basic nature of science."
Upon receiving such a scolding, the Darwin-skeptic who said that evolution is "just a theory, but not a fact" may feel quite bad. She innocently had no intent to violate any rules of semantics or misuse any terms; she merely wanted to communicate her skepticism of neo-Darwinism. In this tangled web of ambiguously defined terms, the Darwin-skeptic is then confronted by a number of confusing questions of rhetoric and semantics:
Question 1. Are Darwinists correct to define "theory" as "a well-substantiated scientific explanation of some aspect of the natural world" or "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence"? Question 2. Under such a strong definition of "theory," does evolution qualify as a "theory"? Question 3. Is it correct to call evolution a "fact"? Question 4. Is it best for Darwin skeptics to call evolution "just a theory, not a fact"? Question 5. All I wanted to convey is that I’m a scientific skeptic of neo-Darwinism. How can I communicate such skepticism without stepping on a semantic land mine and getting scolded by Darwinists?
These are all good questions. In the sections below, I will attempt to answer all five questions, exploring the argument that evolution is "just a theory, not a fact" and providing criticism of people on both sides of this debate, as well as some friendly communications advice for Darwin-skeptics. And from the outset, I should state that I have always opposed using the "evolution is just a theory, not a fact" line to communicate one’s skepticism regarding neo-Darwinian evolution.
According to the 1998 edition of the U.S. National Academy of Sciences' (NAS) Science and Creationism: A View from the National Academy of Sciences, a theory is "a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, and tested hypotheses." In 2008, the NAS released a new edition, Science, Evolution, and Creationism, stating that a theory is "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence." Darwinists routinely invoke these and other similar definitions of "theory" when scolding Darwin-skeptics for calling evolution "just a theory, not a fact." Are Darwinists correct to define "theory" in this fashion? The answer to this question is both yes and no.
"Theory" can have multiple definitions. When I look up "theory" in my 1996 edition of Webster's Encyclopedic Unabridged Dictionary of the English Language (WEUDEL), the word “theory” has 7 or 8 different entries: Question 1: Are Darwinists correct to define "theory" as "a well-substantiated scientific explanation of some aspect of the natural world" or "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence"?
1. a coherent group of general propositions used as principles of explanation for a class of phenomena: Einstein's theory of relativity.
2. a proposed explanation whose status is still conjectural, in contrast to well-established propositions that are regarded as reporting matters of actual fact.
3. Math. a body of principles, theorems, or the like, belonging to one subject: number theory.
4. the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.
5. a particular conception or view of something to be done or of the method of doing it; a system of rules or principles.
6. contemplation or speculation.
7. guess or conjecture.
According to entry #2, "theory" can mean "a proposed explanation whose status is still conjectural, in contrast to well-established propositions that are regarded as reporting matters of actual fact." Similarly, entries #6 and #7 define "theory" as "contemplation or speculation" or "guess or conjecture." We’ll say these comprise the soft definition of theory and represent the definitions that the average person has in mind when they say, "evolution is just a theory, not fact."
The upshot of the soft definition of theory is that Darwinists who imply that the term "theory" can never mean that "conjecture or guess" are in fact wrong, because "theory" can in fact mean conjecture or guess. On the other hand, if you’re a Darwin-skeptic who thinks that "theory" necessarily means "conjecture" or a "guess" and can never mean a verified scientific explanation, then you are wrong: After listing these entries, my 1996 edition of WEUDEL elaborates on proper usage of the word "theory" within the scientific community:
1. THEORY, HYPOTHESIS are used in non-technical contexts to mean untested idea or opinion. The THEORY in technical use is a more or less verified or established explanation accounting for known facts or phenomena: the theory of relativity. A hypothesis is a conjecture put forth as a possible explanation of phenomena or relations, which serve as a basis of argument or experimentation to reach the truth: This idea is only a hypothesis.
Within technical scientific discussions, the term "theory" typically is understood to mean "a more or less verified or established explanation." We’ll call this the hard definition of theory. But is this hard definition of theory the only way that scientists use the word "theory"?
When a Darwin-skeptic says "evolution is a theory, not a fact," Darwinists often pounce and assert that the colloquial or "pejorative" (Glenn Branch's label) usage of "theory" can mean "conjecture" or "guess," but scientists never use the word "theory" to mean conjecture or guess. For example, Branch favorably quotes Ken Miller's 2007 edition of the textbook Biology, implying that there is a united front and complete conformity within the scientific community regarding proper usage of the word "theory": "In science, the word theory applies to a well-tested explanation that unifies a broad range of observations." Such Darwinist claims of unanimity within the scientific community are also questionable.
While scientists do typically imply the "hard" definition when using the word "theory," they don't always use it in that sense. If scientists always meant the "hard" definition of "theory," then scientists would virtually never use the phrase "new theory" because an idea does not attain the status of a theory until it becomes well-established and verified, withstanding many tests until it is no longer "a proposed explanation whose status is still conjectural." Yet a quick search of PubMed for the phrase "new theory" reveals dozens and dozens of hits from the technical scientific literature where scientists offered "a proposed explanation whose status is still conjectural" but called that explanation a theory.
Three recent examples of such usage of "new theory," where theory represented an unverified idea, will suffice.
In the April, 2008 issue of the journal Medical Hypotheses, editor-in-chief Bruce G. Charlton uses the phrase "new theory" multiple times. The meaning implied by the term "theory" in this case was a proposed explanation whose status is still conjectural, in contrast to well-established propositions that are regarded as reporting matters of actual fact. As Charlton observes:
An old joke about the response to revolutionary new scientific theories states that there are three phases on the road to acceptance: 1. The theory is not true; 2. The theory is true, but it is unimportant; 3. The theory is true, and it is important -- but we knew it all along. ... Theory for scientists is like water for fish: the invisible medium in which they swim.
(Bruce G. Charlton, "False, trivial, obvious: Why new and revolutionary theories are typically disrespected," Medical Hypotheses, Vol. 71:1-3 (2008).)
Charlton goes on to say, "When a new theory is revolutionary, then it is perceived as an observation which is incompatible with the old theory. From this perspective either the new theory must be rejected, or else the old theory abandoned." Clearly Charlton uses the word "theory" as if it can, in some circumstances, mean a new idea that has not yet undergone widespread testing and verification, and may not have experienced widespread acceptance.
As a second example, a recent sociology paper from Archives of Suicide Research states, "Although the study has offered some support for the new theory, future research with more rigorous quantitative data needs to be conducted to further test the theory on a more comprehensive level." (J. Zhang, D. Lester, "Psychological Tensions Found in Suicide Notes: A Test for the Strain Theory of Suicide," Archives of Suicide Research, Vol. 12(1):67-73 (2008).) Clearly this study uses the word "theory" to describe a new idea that has not yet been fully verified nor accepted.
Finally, even within the context of evolutionary biology, theory can mean a new idea that does not yet have widespread verification or universal acceptance. A recent article in Current Biology entitled "Social Evolution: The Decline and Fall of Genetic Kin Recognition," by Andy Gardner and Stuart A. West of the Institute of Evolutionary Biology, University of Edinburgh, contains a subheading which asserts, "New theory confirms that genetic kin recognition is inherently unstable, explaining its rarity." Yet the article goes on to describe a vigorous scientific debate between evolutionary biologists about whether kin selection is a genetically viable explanation to account for the evolutionary origin of altruism and cooperation. According to the article, a new study concludes that "there is relatively poor empirical support for this mechanism in nature" because "[a] new theoretical study of genetic kin recognition … reveals that, left to its own evolutionary devices, this mechanism will drive itself to ruin." But other leaders in that field disagree, implying that this "new theory" is not "a well-substantiated scientific explanation of some aspect of the natural world" or "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence."
There are many other examples from the technical literature where theory is used in a similar sense, and it does not mean "a more or less verified or established explanation." It should be clear that scientists sometimes DO use the term "theory" to refer to a new idea that has not yet undergone extensive testing and is simply "a proposed explanation whose status is still conjectural."
We must return to the question, Are Darwinists correct to define "theory" as "a well-substantiated scientific explanation of some aspect of the natural world" or "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence"? The answer is yes, but they are not entitled to claim that such a hard definition is the exclusively acceptable usage of theory both for scientists and non-scientists. Darwinists are wrong to imply that scientists always necessarily use the hard definition of theory, because even scientists occasionally use theory as if it means new idea, or a "proposed explanation whose status is still conjectural." The Darwinist claim that "theory" is always and exclusively used by scientists to mean a verified and well-established explanation is a fiction invented by Darwinists seeking grounds to scold as ignorant those Darwin-skeptics who call evolution "just a theory."
The problem underlying debates over the proper usage of theory is that the term can have multiple definitions, even among scientists, ranging from "a proposed explanation whose status is still conjectural, in contrast to well-established propositions" to "a more or less verified or established explanation." But the upshot is this: Because the term "theory" can mean "a more or less verified or established explanation," it is inappropriate for a Darwin skeptic who is trying to communicate doubts about Darwin to use the "evolution is a theory, not a fact" line, because it ignores the truth that in many venues, theory does indeed mean, as WEUDEL explains, "a more or less verified or established explanation."
It seems clear that scientists can use the word "theory" to mean "conjecture," but it is also fair to say that typical circumstances, when scientists say "theory," they mean the hard usage of the term: "a more or less verified or established explanation." This thus leads to the question, under such a strong definition of the term, does evolution qualify as a theory?
Assuming that we are using the hard definition of theory, different people will give different answers to that question. Under such an understanding of the term, if we define theory as "a more or less verified or established explanation," then theory is in the eye of the beholder. Darwin-skeptics will not agree that neo-Darwinian evolution is "a more or less verified or established explanation." But Darwinists will agree. So the question over whether neo-Darwinian evolution should be called a "theory" is not the core question of this debate. A better question would be: "Is neo-Darwinian evolution ‘a more or less verified or established explanation’?"
Darwinists have the right to believe that neo-Darwinian is a verified and established explanation--i.e. that it meets the hard definition of theory. But they do not have the right to insist that Darwin-skeptics must call evolution a "theory," so defined. While Darwinists are correct that the technical definition of "theory" means a well-established and verified explanation, they should not insist that evolution can never be called "just a theory." When they do this, they are actually imposing onto the debate their conclusion that evolution must be considered by all to be a verified and established explanation. Were they to tolerantly allow Darwin-skeptics to dissent from the orthodox neo-Darwinian position, Darwinists would not insist that Darwin-skeptics entirely abandon the phrase "evolution is just a theory."
However, given that the technical, scientific, hard definition of theory does typically mean a well-established and verified explanation, then it is best if Darwin-skeptics take the high road and avoid calling neo-Darwinian evolution "just a theory." And as we shall see in the next section, the question "is evolution a 'more or less verified or established explanation'?" is also a complex question, for it can also depend on the definition of "evolution."
A new article in Current Biology about Darwin Day celebrations quoted Johnjoe McFadden from the University of Surrey stating that "evolution is no longer just a theory. It is as much a fact as gravity or erosion. Scientists have measured evolutionary changes in scores of organisms." The leading 20th century evolutionary biologist Ernst Mayr quite dogmatically (and wrongly) claimed that, "No educated person any longer questions the validity of the so-called theory of evolution, which we now know to be a simple fact." Similarly, according to the ardently pro-Darwin U.S. National Academy of Sciences (NAS), evolution is a "fact":
Is Evolution a Theory or a Fact? It is both. But that answer requires looking more deeply at the meanings of the words "theory" and "fact."
(U.S. National Academy of Sciences, Science, Evolution, and Creationism, pg. 11 (National Academy Press, 2008).)
What these Darwinist authors miss is that the legitimacy of calling evolution a "fact" depends on the meaning of the word "evolution."
The debate over evolution can be confusing because equivocation has crept into the discussion. Some people use evolution to refer to something as simple as small changes in the sizes of birds’ beaks. Others use the same word to mean something much more far-reaching. Used the first way, the term "evolution" isn’t controversial at all; used the latter way, it’s hotly debated. Used equivocally, evolution is too imprecise to be useful in a scientific discussion. Darwin’s theory is not a single idea. Instead, it is made up of several related ideas, each supported by specific arguments:***
So is evolution a fact? If by "evolution" one simply means "evolution #1," i.e. small-scale change over time within a species, then evolution is indeed a fact. No one disputes this kind of "evolution." Thus when Johnjoe McFadden states that "[s]cientists have measured evolutionary changes in scores of organisms" and therefore evolution "is as much a fact as gravity or erosion," he is stating the obvious because he is simply referring to evolution #1.
But Dr. McFadden is pulling a bait-and-switch: he is using relatively trivial examples of evolution #1 to bolster more controversial definitions of "evolution." Thus if by "evolution" one means universal common descent (evolution #2), or neo-Darwinian evolution (evolution #3), where the primary adaptive force building the complexity of life is unguided natural selection acting upon random mutations, then many scientists would argue that such "evolution" most certainly is not a fact.
A Closer Look at the NAS’ Mistake
Finally, consider how the NAS defines evolution as a fact:
In science, a "fact" typically refers to an observation, measurement, or other form of evidence that can be expected to occur the same way under similar circumstances. However, scientists also use the term "fact" to refer to a scientific explanation that has been tested and confirmed so many times that there is no longer a compelling reason to keep testing it or looking for additional examples. In that respect, the past and continuing occurrence of evolution is a scientific fact. Because the evidence supporting it is so strong, scientists no longer question whether biological evolution has occurred and is continuing to occur. Instead, they investigate the mechanisms of evolution, how rapidly evolution can take place, and related questions.
(U.S. National Academy of Sciences, Science, Evolution, and Creationism, pg. 11 (National Academy Press, 2008).)
I won’t dispute the NAS's definition of fact, but it’s clear that unless by "evolution" they mean evolution #1, then there are many scientists who will disagree with their claim that evolution is a fact. However, the NAS DID define evolution as evolution #3, i.e. being driven by natural selection acting upon mutation-caused variation:
In the century and a half since Darwin, scientists have uncovered exquisite details about many of the mechanisms that underlie biological variation, inheritance, and natural selection, and they have shown how these mechanisms lead to biological change over time. Because of this immense body of evidence, scientists treat the occurrence of evolution as one of the most securely established of scientific facts. … The atomic structure of matter, the genetic basis of heredity, the circulation of blood, gravitation and planetary motion, and the process of biological evolution by natural selection are just a few examples of a very large number of scientific explanations that have been overwhelmingly substantiated.
(U.S. National Academy of Sciences, Science, Evolution, and Creationism, pg. xiii, 12 (National Academy Press, 2008).)
The NAS is wrong. Since the NAS defines "evolution" as full-blown neo-Darwinian evolution, there are many scientists who will not agree that it is a fact.
Question 4. Is it best for Darwin skeptics to call evolution "just a theory, not a fact"?
In short, no. Having taken over a dozen courses covering evolutionary biology at both the undergraduate and graduate levels, I’m a scientific skeptic of neo-Darwinism. But I’ve long opposed using such a rhetorical line of "evolution is just a theory, not a fact" to oppose evolution because it gets you caught up in a semantic debate over the proper definition of fact and theory, and communicates very little about the most important component of this debate -- the scientific evidence. (For an early example of my writings on this topic, see my "Response to the ACLU ID FAQ.") I’ll start with criticism of people on my own side of this debate by offering four reasons why I oppose using the "evolution is just a theory, not a fact" line:
1. The statement "evolution is just a theory, not a fact," hopes to convey some kind of skepticism regarding evolution, but it fails to adequately define the term. As we learned in Question 3, no one doubts evolution when it is defined as "populations of living organisms change over time." Evolution so-defined is an unquestionable fact. But when evolution is defined as "natural selection acting on random mutation serves as the primary driving force that built the complexity of life" or even "all species share a universal common ancestor" (collectively called "neo-Darwinian evolution") then you’ve traipsed into more controversial definitions of evolution.
2. The "evolution is just a theory" line is simply not a good way of expressing skepticism about neo-Darwinian evolution because it assumes that a theory is something which necessarily lacks evidentiary support. As we learned in Question 1, the problem with this phrase is that the word "theory" can indeed mean a scientific idea that is well-backed by large amounts of scientific evidence.
3. When someone says "evolution is just a theory," it sounds like the speaker cannot cite actual scientific evidence against evolution, and that the only objection the speaker can muster is based upon appealing to postmodern rhetoric which asserts that we really can’t know if anything is true. The truth is that science is capable of studying the validity of historical scientific theories such as neo-Darwinism, but the "evolution is just a theory" line makes it sound like the speaker is not interested in studying or discussing that evidence. In the debate over evolution, discussions of evidence are what matter most. As stated previously, calling something a theory doesn't necessarily tell you about the state of the evidence. The best way to express dissent from evolution is to actually discuss its failure to explain the scientific evidence.
4. The "evolution is just a theory" line can come off as if the speaker really thinks "evolution is just a guess so I don't have to believe it if I don't want to." In fact, neo-Darwinian evolution as a whole is not merely a guess, and most Darwinian scientists will provide reasons why they think it is the best explanation for the diversification of life. If you’re like me, and you think that neo-Darwinian evolution has scientific problems, then you should be able to provide reasons why you're a skeptic beyond stating "it's just a theory." As noted above, the best strategy is for you to be prepared to give a few specific scientific reasons why you question Darwinian evolution.
So if we shouldn’t call evolution "just a theory, not a fact" then how should us Darwin-skeptics refer to evolution? Theory? Fact? Hypothesis? Something else? I’ll explore this question in the final section of this article.
Question 5. All I wanted to convey is that I’m a scientific skeptic of neo-Darwinism. How can I communicate such skepticism without stepping on a semantic land mine and getting scolded by Darwinists?
Great scientific claims must be backed by great scientific evidence. When most people claim that "evolution is just a theory, not a fact," what they really mean is that there is not convincing scientific evidence to justify the great claim that all life is related through universal common ancestry and that it evolved via an process of unguided natural selection acting upon random mutation. Doubts about neo-Darwinian evolution might stem from:
When evolution is defined as mere change over time within species, no one disputes that such evolution is a fact. But neo-Darwinian evolution -- the great claim that unguided natural selection acting upon random mutations is the driving force that produced the complexity of life -- has many scientific problems because such random and unguided processes do not build new complex biological features. According to the technical definitions of "theory," "fact," and "hypothesis," such neo-Darwinian evolution is neither theory nor fact. It’s just a hypothesis."Closing Thoughts