Q & A on Evolution and Intelligent Design

What is evolution?

Evolution is a broad, well-tested description of how Earth's present-day life forms arose from common ancestors reaching back to the simplest one-celled organisms almost four billion years ago. It helps explain both the similarities and the differences in the enormous number of living organisms we see around us.

By studying the sequence of changes in fossils found in successive layers of rock as well as the molecular evidence provided by modern genetics, scientists have been able to trace how ancient organisms — through a process of descent with modification — gave rise to profound changes in populations over time. Many new anatomical forms have appeared, while others have disappeared. In a very real sense, we are distant genetic cousins to all living organisms, from bacteria to whales.

Evolution occurs in populations when heritable changes are passed from one generation to the next. Genetic variation, whether through random mutations or the gene shuffling that occurs during sexual reproduction, sets the stage for evolutionary change. That change is driven by forces such as natural selection, in which organisms with advantageous traits, such as color variations in insects that cloak some of them from predators, are better enabled to survive and pass their genes on to future generations.

Ultimately, evolution explains both small-scale changes within populations and large-scale changes in which new species diverge from a common ancestor over many generations.

Is evolution "just a theory?"

In detective novels, a "theory" is little more than an educated guess, often based on a few circumstantial facts. In science, the word "theory" means much more. A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of the real world. The theory of biological evolution is more than "just a theory." It is as factual an explanation of the universe as the atomic theory of matter or the germ theory of disease. Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact.

Is there "evidence against" contemporary evolutionary theory?

No. There are still many puzzles in biology about the particular pathways of the evolutionary process and how various species are related to one another. However, these puzzles neither invalidate nor challenge Darwin's basic theory of "descent with modification" nor the theory's present form that incorporates and is supported by the genetic sciences. Contemporary evolutionary theory provides the conceptual framework in which these puzzles can be addressed and points toward ways to solve them.

Is there a growing body of scientists who doubt that evolution happened?

No. The consensus among scientists in many fields, and especially those who study the subject, is that contemporary evolutionary theory provides a robust, well-tested explanation for the history of life on earth and for the similarity within the diversity of existing organisms. Very few scientists doubt that evolution happened, although there is lively ongoing inquiry about the details of how it happened. Of the few scientists who criticize contemporary evolutionary theory, most do no research in the field, and so their opinions have little significance for scientists who do.

What is intelligent design?

"Intelligent design" consists of two hypothetical claims about the history of the universe and of life: first, that some structures or processes in nature are "irreducibly complex" and could not have originated through small changes over long periods of time; and second, that some structures or processes in nature are expressions of "complex specified information" that can only be the product of an intelligent agent.

Is intelligent design a scientific alternative to contemporary evolutionary theory?

No. Intelligent design proponents may use the language of science, but they do not use its methodology. They have yet to propose meaningful tests for their claims, there are no reports of current research on these hypotheses at relevant scientific society meetings, and there is no body of research on these hypotheses published in relevant scientific journals. So, intelligent design has not been demonstrated to be a scientific theory. While living things are remarkably complex, scientists have shown that careful, systematic study of them can yield tremendous insights about their functions and origins (as it has in the past).

Intelligent design necessarily presupposes that there is an "intelligent designer" outside of nature who, from the beginning or from time to time, inserts design into the world around us. But whether there is an intelligent designer is a matter of religious faith rather than a scientifically testable question.

Why did AAAS boycott the recent Kansas State Board of Education hearings on evolution?

The Kansas State Board of Education, which is dominated by intelligent design advocates, scheduled a series of hearings beginning May 5 on proposed revisions to state science standards. AAAS was invited to testify and "provide expert opinion regarding the mainstream scientific view of the nature of science." After much consideration, AAAS respectfully declined to participate, honoring a boycott called by the grassroots pro-science organization, Kansas Citizens for Science. We saw little purpose in a forum where evolution would be juxtaposed against "intelligent design," an unsubstantiated alternative that is a matter of religious faith, not facts. The State Board established a format which implied that scientific conclusions could be based simply on the weight of witnesses' opinions rather than on scientific evidence. We chose to support leaders of the Kansas science community, who promoted the boycott and described the hearings as rigged by proponents of intelligent design. In the end, with the exception of a Kansas civil rights attorney, who pointed out the farcical nature of the proceedings, only ID proponents testified.

Aren't scientists really just afraid to debate proponents of intelligent design?

No, scientists actually thrive on debate, but only according to the norms and standards of scientific investigation and discourse. Scientists are bound by existing facts while the opponents are not constrained by sticking to the verifiable evidence and data.

Scientists see no point — and much danger — in pitting a scientific concept like evolution against a non-scientific article of religious faith like intelligent design. By agreeing to debate evolution, scientists would be offering proponents of intelligent design a veneer of scientific respectability that has not been earned in the rough-and-tumble of everyday science. They also buy into a situation where the public might expect an either-or outcome between science and religion.

Doesn't fairness require that alternatives to contemporary evolutionary theory be taught in the public schools?

No. This is not about fairness. Science requires adherence to standards of research conduct and process. Intelligent design has not met those standards and should not be taught in science classrooms. If anything, it is unfair for proponents of a non-scientific claim to try to force their views into science classrooms.

Still, it appears that scientists are arrogant or elitist when they refuse to participate in debates.

Scientists recognize that they can appear aloof by refusing to appear in debates with intelligent design advocates in any and all forums they demand. But scientific inquiry and debate is not subject to the same ground rules as a media talk show. Scientific discourse demands experimental evidence.

Scientists, including officials at AAAS and other groups, have been very willing to talk to reporters, community groups and others about their reasons for supporting evolution and their misgivings about proposed school board actions in Kansas and elsewhere. We trust the good judgment of parents and community leaders when all of the facts are known.

Are scientists trying to stifle discussion of intelligent design?

We do not want to censor discussion of intelligent design in the proper setting but the school science classroom is not that setting. Nor do we want to portray evolution as some carved-in-stone dogma. Science is an ongoing process, with new evidence accepted and weighed constantly. Intelligent design advocates have yet to contribute in a scientifically rigorous manner to that process.

AAAS has worked hard to guarantee that children get a first-class science education. We've helped set the objectives for what should be taught and learned in science classrooms. We want to prevent an erosion of the quality of science education. In the case of Kansas, that would be unfortunate at a time when the state is trying to attract high-tech industry and it, like other U.S. states, is trying to nurture more homegrown science talent.

Are science and religion inherently opposed?

No. Science does not take a position on an intelligent designer, which is a matter of religious faith, and is not testable scientifically. AAAS and other scientific groups do not want to create the impression that religion and science are inherently in conflict. They live together quite comfortably, including in the minds of many scientists.

Science and religion ask different questions about the world. Many individual scientists are deeply religious. They see scientific investigation and religious faith as complementary components of a well-rounded life.

Can science stimulate religious thought?

Yes. A particular religion's understanding of the world provides the context from which questions of meaning emerge. A development in science may provide a new more reliable explanation of the structure and processes of the world. This may be different from the understanding of the world that is presumed in a particular religion. What may appear to be a conflict between science and religion is actually a contrast between earlier and more recent understandings of the world (e.g., between an earth-centered universe and a sun-centered universe) and can be a constructive stimulus for religious inquiry. In fact, Jewish, Christian, Muslim, Buddhist and Hindu scholars have sought positive ways to relate evolutionary theory with their religious traditions.

Is the science classroom the appropriate place to discuss the religious interpretations of science?

No. Religion is a subject of inquiry in historical, philosophical and social studies, not in science. So, discussion about religion is most appropriate in the social studies or humanities curriculum, not in the science curriculum.

Have scientists underestimated the impact of the intelligent design movement?

Many scientists probably have been caught unawares, in part, because they don't see an inherent conflict between science and religion. They often are more comfortable in the laboratory, doing science and communicating it to students, than they are in the public arena. But it is clear they can no longer afford to ignore the political reality of the intelligent design movement and its effort to sway school boards and curriculum committees in many states and communities. The AAAS is determined to remain engaged on this issue and encourages other scientific groups to do so as well, particularly at the grass roots level.

What are the stakes?

The risk, if intelligent design is incorporated into school curricula, is to undermine scientific credibility and the ability of young people to distinguish science from non-science. And that is what matters more, in the longer term, than the specific battles over intelligent design versus evolution. In Kansas, advocates of "intelligent design" are attempting to redefine what is and is not science, in direct conflict with the science standards recommended by both the National Academy of Sciences and AAAS in earlier work. They are pushing the board to reject a definition that limits science to natural explanations for what's observed in the world. They want to define it so that science will include supernatural explanations.