Thursday, April 19, 2012

Evolution: Theory, Fact or Law


Addendum: The Law of Evolution

In the physical sciences there are many observations or facts that have given rise to generalizations: two of these are the law of conservation of matter and the law of definite proportions (which states that when two or more elements combine to form a compound they do so in definite proportions by weight). The statements of facts and their convenient generalization to laws are expressed in terms of macroscopically observable and weighable quantities. The overarching explanation for these laws is achieved in atomic theory, which is expressed in terms of invisible atoms and molecules. No one thinks that atomic theory is “just a theory,” for it possesses extraordinary explanatory power and provides the context in which many of the conveniences of our civilization depend. Thus we proceed from many observations or facts to their generalization in terms of laws, both levels macroscopic, to a theory expressed in terms of invisible entities.

If we now apply this scheme to biology, we see that the concept of evolution is at the law level, as it summarizes the results of a large number of observations or facts about organisms. The analogous theory is natural selection or other means by which evolution is achieved. Unknown nearly 150 years ago to Darwin, explanations of macroscopic evolution in terms of microscopic genes and molecular sequences of nucleic bases in DNA are known to us. Placing the concept of evolution at the law level clarifies its status; it is not a theory.

In contrast, the premise of Intelligent Design fails to meet even the most fundamental elements of rational inquiry. By being able to account for everything by divine edict, Intelligent Design explains nothing.

Only a Theory? Framing the Evolution/Creation Issue
By: David Morrison, Skeptical Inquirer, November/December 2005
David Morrison's photo
David Morrison is a long-time NASA senior scientist and Committee for Skeptical Inquiry fellow. He now divides his time between the SETI Institute and the NASA Lunar Science Institute. He hosts the "Ask an Astrobiologist" column at NASA's website.
Evolution opponents are framing the issues to our disadvantage; they focus on the phrase “theory of evolution,” when theory is today understood by the public as a tentative concept unsupported by evidence.

Public opinion polls tell us that we are losing the battle to explain the nature of evolution and the central role that evolutionary concepts play in modern science. Tens of millions of Americans scoff at evolution and try to protect their children from what they consider to be a pernicious concept.

Given the overwhelming scientific support for evolution, we must be doing something wrong in discussing this issue with the public. There are several ways in which scientists and educators might enhance their effectiveness in this debate. The problems relate to framing the issues, or rather, allowing the opponents of evolution to frame them. Framing involves the selective use of language or context totrigger responses, either support or opposition. We see it in the often deceptive titles of legislation, such as a “clear skies act” or “forest renewal act” or, on the other side, a “death tax.” “Pro-choice” or “pro-life” advocates are always careful to frame their position with the proper emotion-charged terms. (The subject is artfully described in George Lakoff’s book Don’t Think of an Elephant.)

As a prime example, we doom our communications efforts with many nonscientists by defending the “theory of evolution.” Theory is quite simply the wrong word. Polls indicate that three quarters of Americans agreed that “evolution is commonly referred to as the theory of evolution because it has not yet been proven scientifically.” Those who advocate adding “only a theory” disclaimers in textbooks know that to call evolution a is sufficient to undermine its acceptance.

Channeling the discussion into a debate over the “theory of evolution” is an example of framing. Since the great majority of Americans understand the word theory to imply uncertainty and vagueness, the name itself predisposes the answer. It is as if a criminal defendant were described by the judge and other court officials as “the murderer.” Not many juries would want to let a known murderer free, no matter how the evidence was presented. The one who frames the debate often wins.

Yet many proponents of evolution seem content to argue about the “theory of evolution” and its educational role. As scientists, they were taught that a scientific theory is a systematic set of principles that has been shown to fit the facts, and has stood up against attempts to prove it false. A theory is thus the highest level of understanding, synthesizing a wide variety of observations and experiments. But that is not what the word theory means to 99 percent of Americans, including many scientists and educators when they are outside the classroom.

Dictionaries have noted the changing definition of this word. Older dictionaries give preference to the scientific definition and consider the use of theory to refer to a guess or hunch to be a form of slang. Today, the slang meaning prevails, and a theory is a belief, something taken to be true without proof, an assumption, a suggestion, a hypothesis. Similarly, theoretical is used as a synonym for tentative, an idea that has not been tested with observations.

How do we really use the term in everyday language? A theory is a hunch that a detective comes up with in a murder mystery. It is one of several competing ideas, none of them proved. Fringe theories and conspiracy theories are crazy ideas that are out of the mainstream. New medicines or changes in the tax laws may be good in theory but don’t work in practice. Among some scientists, theorists are thought to lack solid grounding in the facts (see the accompanying sidebar).

What about scientific usage? We don’t hear much anymore about the Theory of Gravitation, or the Atomic Theory of Matter, or the Theory of Plate Tectonics. These phrases have a vaguely antique flavor. Gravitation and atoms and plate tectonics are accepted as legitimate subjects that don’t need the preface “Theory of.” The only two areas where “Theory of” remains in common use are Theory of Relativity and Theory of Evolution. Relativity is associated with Einstein, a genius whose work was abstract and unintelligible to laypeople. I doubt if most people realize that the principles of relativity have been tested, or that relativity has practical implications, for example in calculating the interplanetary trajectories of spacecraft. Judge for yourselves what this association implies for “Theory of Evolution.”

There is another usage that should be mentioned: theory as a discipline, such as organization theory, color theory, economic theory, music theory, etc. These phrases imply the existence of a knowledge base or conceptual framework, and their names are given to university courses or areas of specialization. In science there are chaos theory, cosmological theory, information theory, and—yes—evolutionary theory (as used in the title of Steve Gould’s last book). This usage is, however, rarely discussed in arguments about “only a theory.”

Real-world Use of the Word Theory

The following examples were encountered in the summer of 2005:

From a story:

End of Conspiracy Theories? Spacecraft Snoops Apollo Moon Sites
Fringe theorists have said images of the waving flag—on a Moon with no atmosphere—and other oddities show that NASA never really went to the Moon.

From a San Jose Mercury News story on the mystery that no tsunami was generated by Indonesia’s 8.7 earthquake of March 28, 2005:

Scientists have two theories about what happened Monday. Either no tsunami was produced, or one was formed but headed out to sea and away from populated areas. Eric Geist of USGS said “We’ll just have to wait and see.”

From the California Academy of Science exhibit on fossils in the San Francisco Airport, August 2005:

Scientists have a number of theories about why ammonites develop spines on their shells.

From Skeptical Briefs (June 2005, vol. 15 no. 2):

[Some cancer treatments] seem promising in theory, but don’t work in fact.

From The New York Times, July 22, 2005:

Echoes and Theories, but No Solid Links in London Bombings
Investigators said their leading theory was that the latest attempted bombings were a copycat-style attack.

From David Brooks on PBS, in reference to speculation about Karl Rove:

This is a case where the theory has gotten way out in front of the facts.

From a NPR commentary on health care, August 2, 2005:

False positives in blood tests are a theoretical possibility, but are rare in practice.

From the History Channel special “Ape to Man,” August 2005:

Human evolution remained little more than a theory until evidence was found. . . .
If we accept the framing that calls this topic the theory of evolution, we face a dilemma. Some people just ignore the problem and concentrate on presenting the facts of evolution. They may believe that these facts and their implications are self-evident. But the human brain does not always work that way. We have seen recent examples. The majority of voters who supported the 2004 re-election of George W. Bush told pollsters that they believed that Saddam Hussein had weapons of mass destruction and that he had been behind the September 11 terrorist attacks, despite countless news stories to the contrary. Many people believe that airplanes are more dangerous than cars, no matter what risk statistics are presented. Even after well-conducted trials showed that herbal medicines such as echinacea are ineffective, public sales have remained strong.

Alternatively, many scientists and educators recognize the public misunderstanding of the scientific term theory and try to explain this to the audience. In her excellent book Evolution vs. Creationism, Eugenie Scott devotes much of the first chapter to the scientific meaning of the terms theory, hypothesis, falsification, etc. However, few members of a nonscientific audience with concerns about teaching evolution to their children are ready to accept that this word, whose meaning they know perfectly well, has in fact an almost opposite definition in science. Thus before asking the audience to consider that their opinions about evolution might be wrong, we start by asking them to accept a contrary definition for a familiar word. Anyone who teaches knows how hard it is for students to unlearn things they already know and believe. So why do we accept this wholly unnecessary burden when discussing evolution? No wonder those who frame evolution as a theory often win.

We should be discussing simply evolution, the same way we might discuss plate tectonics or genetics or any other branch of science. To debate the “theory of evolution” is a trap. It is letting our opponents frame the discussion to their benefit. Once we stop defending the theory of evolution, we are also free to criticize “only a theory” disclaimers in textbooks without apology or diversionary explanations.

The Either/Or Fallacy

The concept of framing has other implications for the creation-evolution debate. One that we are all familiar with is the effort to portray this as a choice between two models—godless evolution versus divinely inspired creationism. In a two-model formulation, any perceived difficulty with evolution becomes support for creationism. We should not accept this framing of the conflict. Actually, I would think that today it would be obvious that there are at least three models on the table: evolution, the young-earth creationism of biblical literalists, and the more sophisticated concept of Intelligent Design (ID), which accepts the age of the universe and the change in Earth’s biota over time. It is a tribute to the discipline of the anti-evolution camp that they have avoided most public debates between the biblical literalists and ID. But we are free to exploit this split and to ask which alternative is proposed to be taught alongside evolution in science classes.

Most opponents of evolution in the schools are Christian fundamentalists, and many of them believe that evolution is a moral issue, a struggle between the forces of good and evil. Obviously proponents of evolution do not see it this way. What we want is a level playing field where we can present the facts. But as noted above, facts often lose out in a confrontation with deeply held beliefs.

To achieve a level playing field, we should avoid debating evolution in a religious context. Specifically, we should not speak on these issues in a church other than our own. In an unfamiliar church speaking to an audience of like-minded opponents of evolution, all the cards are stacked against us—not because there is anything antireligious about evolution, but because the audience believes there is. This situation also creates a temptation to debate religion itself, such as arguing about the “true” message of the first book of Genesis or contrasting the beliefs of Roman Catholics and fundamentalist Protestants. This is not likely to be a winning strategy for the scientist, who is again a victim of framing.

An Issue of Values

Many antievolutionists base their opposition not on scientific issues, but on their belief that evolution threatens their value system, specifically their family values. I don’t see why we should not face this issue directly. Family values are not the monopoly of the creationist advocates. Most in these audiences will share a common interest in the education of their children, which is a fundamental American family value.

If I were speaking to an audience of parents, I would stress that evolution is central to many sciences, and that one cannot be a scientist without understanding it. I would note that students who don’t understand evolution will have trouble getting into the best colleges. I would comment on the great number of scientists and engineers being graduated in “competitor” countries like China, and note that American students are not top scorers in international science tests. We can make a persuasive and nonpartisan case that the future of the nation depends on its scientific and technical literacy. Relatively few Americans will reject such arguments and state a preference for ignorance. Teaching evolution is part of a bigger issue of the competitiveness and economic well being of the nation (and of the state and local community). This is a real issue of values, for our children and their futures. And it is an issue that might appeal to lay members of school boards and textbook selection committees.

Health is another value issue. Medical research is supported by Americans across a wide political spectrum. How many people understand the role of evolution in the development of new medical treatments? Or the place played by genetics in creating new drugs? There is no more dramatic (or scary) example of evolution than the emergence of drug-resistant pathogens, as well as recent diseases such as AIDS. Newspaper stories about threatened pandemics due to mutations in avian flu or other emerging viruses can only be understood in an evolutionary context. Suppressing the study of evolution cuts off future opportunities to improve public health. Surely this values argument has wide appeal.

Beyond Biology

We also suffer when we accept that evolution should be debated purely in terms of biology and biology courses. In the present American public school system, these courses are already watered-down so that evolution is likely to be mentioned in only or one or two chapters or discussed in only one study unit of a biology course. It is easy to belittle a subject that seems so marginal. We should reframe this issue in terms of crosscutting ideas that affect all science. The audience should know that evolution and the concept of deep time are essential to geology and astronomy and genetics and pharmacology as well as high-school biology. It is also an opportunity to tell an audience how many people in this country are working in evolution-related jobs. If the audience comes from a traditional conservative religious background, they may have no idea that evolution is widely accepted among scientists and medical professionals and that it contributes to the livelihood of many Americans.

Many conservative Americans support competition and believe that free-market economic conditions are essential to national success. Most of them would be shocked to know that this philosophy has traditionally been known as social or economic Darwinism. Perhaps we should note that Darwinian natural selection is in many ways nature’s equivalent to free-market competition. The other side of this argument addresses the belief that evolution leads to socialism and communism. Perhaps it is worth noting that Stalin’s support for the anti-Darwinian biologist Trofim Lysenko set back Soviet agriculture for a generation and contributed to the starvation of millions of Russians.

Finally, we can reframe the issue in terms that do not immediately offend a conservative religious audience. The context in which most opponents fear and reject evolution is that of human origins. The scientific story of the evolution of our human ancestors is fascinating, but it also provokes the strongest resistance. My own interests, as an astrobiologist, are in microbial evolution, which is a less threatening subject. I remember a young teacher coming up to me after a lecture and saying how amazed she was that I had talked for an hour about evolution and the history of life without mentioning primate evolution or human origins. I am not suggesting that we ignore the fascinating story of homonid evolution, but I bet that there are many people who would be more receptive to evolutionary concepts if we refrained from an in-your-face challenge to their convictions about human origins or the nature of the human soul.

Another topic that is controversial is the origin of life. Creationists love to confuse origins with evolution. They frequently use criticisms of, for example, the relevance of the Miller-Urey experiment to undercut the entire concept of biological evolution. Let’s not be sidetracked into the problems of the origin of life. While a great deal of research has been done to define the conditions under which life began on Earth and to understand basic biochemistry, the actual process by which living things emerged is not understood by science. I believe we can and should admit this mystery. There may be many people who will open their minds to the ideas of evolution as long as we don’t claim that science has all the answers, especially about the ultimate origin of life and the meaning of being human. These topics can be explored later, when we have overcome initial emotional resistance to any form of evolution.

Above all, I hope that we can frame the evolution-creationist debate in ways that open our audience to the exciting ideas and accomplishments of science. When appropriate, we should be happy to defend teaching evolution in the context of family values and economic advantage as well as pure science. There is no reason to make this a debate about religion; we are almost sure to lose such a confrontation. But we must also understand where our audience is coming from and find ways to present the science in a non-confrontational and accessible way.

SI on Evolution and ID

Here is a list of some other Skeptical Inquirer articles on Intelligent Design and creationism.
  • Charles Sullivan and Cameron McPherson Smith, “Getting the Monkey off Darwin’s Back: Four Common Myths about Evolution,” May/June 2005
  • Dennis R. Trumble, “One Longsome Argument,” March/April 2005
  • Robert Camp, “‘Teach the Controversy’: An Intelligently Designed Ruse,” September/October 2004
  • Bruce and Frances Martin, “Neither Intelligent nor Designed,” November/December 2003
  • Mark Perakh, “A Presentation without Arguments: Dembski Disappoints,” November/ December 2002
  • Mark A. Wilson, “‘Geology Confronts Creationism’: An Undergraduate Science Curriculum,” January/February 2002
  • Randy Moore, “Educational Malpractice: Why Do So Many Biology Teachers Endorse Creationism?” November/December 2001
  • Taner Edis, “Darwin in Mind: ‘Intelligent Design’ Meets Artificial Intelligence,” March/April 2001
  • David Roche, “A Bit Confused: Creationism and Information Theory,” March/April 2001
  • Martin Gardner, “Intelligent Design and Phillip Johnson,” November/December 1997 (our earliest article on ID) News Articles/Editorials:
  • “Time for Science to Go on the Offense,” July/August 2005
  • “AAAS Board Urges Opposing ‘Intelligent Design’ Theory in Science Classes,” March/April 2003
  • “Botanical Society of America’s Statement on Evolution,” November/December 2003
  • “Bogus Poll of Scientists Latest Twist in ID/Creationists Fight against Science Standards,” November/December 2003
  • “American Association of Physics Teachers Statement on the Teaching of Evolution and Cosmology,” January/February 2000
  • “Science Trumps Creationism in New Mexico,” January/February 2000

David Morrison

David Morrison's photo David Morrison is a long-time NASA senior scientist and Committee for Skeptical Inquiry fellow. He now divides his time between the SETI Institute and the NASA Lunar Science Institute. He hosts the "Ask an Astrobiologist" column at NASA's website.

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