For well over a hundred years, evolution has been the unifying theory of biology. It is supported by overwhelming quantities of high-quality evidence, both experimental and observed in the field, and by literally thousands of peer-reviewed studies from a wide variety of scientific disciplines. It explains and unifies a vast diversity of natural phenomena, and no hypothesis proposed to replace it has ever stood up to scientific scrutiny, nor enjoyed similar explanatory success. Within the scientific community, evolution is as solidly established and uncontroversial as gravity, and enjoys the support of the overwhelming majority of qualified scientists as well as renowned scientific bodies around the world. Creationism, by contrast, was long ago falsified and discarded by the scientific community, and today survives mainly in fringe institutes funded by religious fundamentalists.
When asked why this is so, if evolution is as obviously false as they claim, creationists inevitably resort to making claims about an academic conspiracy. The details differ, but the general idea is always the same – either the scientific community knows evolution is false and is conspiring to prevent people from finding that out, or it has merely become so invested in evolution that it will no longer consider any other viewpoint.
However, there is another creationist tactic that directly contradicts this argument: creationists presenting quotes from famous evolutionary biologists which seem to say that scientists cannot agree and therefore evolution is “a theory in crisis”. (See the Talk.Origins Quote Mine Project for an extensive list of such quotes, along with responses.)
The quotes which creationists present in this way only rarely mean what they appear to say. Instead, most of them have been “mined” from the scientific literature, with context removed or words omitted so that they seem to say something completely different from their author’s intended meaning. Simply looking up the sources from which these quotes were cited usually confirms that their original meaning has been distorted; most commonly, this is done by taking articles written by scientists arguing about some particular aspect of how evolution happens and stripping context to make the author appear to be expressing doubt about whether evolution happens at all. Another perennial favorite tactic is to quote a scientist wondering about a lack of evidence in a certain area, when that scientist lived or wrote before a discovery filling that particular gap, thus falsely implying that the problem is still unsolved.
However, the questionable honesty of this tactic aside, creationists rarely seem to notice that these two arguments directly contradict each other. If evolution is the consensus of the scientific community because of academic petrifaction or conspiracy, then scientists would not be arguing about it, and it could not be a “theory in crisis”. On the other hand, if scientists do argue about evolution, then it shows that the scientific community is not too set in its ways to consider new ideas, and creationism’s failure to gain scientists’ allegiance must be because it intrinsically lacks merit.
That the latter scenario is indeed the case can be shown by examining other fields of science. Science frequently experiences debates and revolutions of knowledge that overturn long-accepted ideas. For example, the field of physics has seen two major upheavals in the twentieth century alone, first by Einstein’s theory of relativity, then by quantum mechanics. Both of these were complex theories with bizarre implications that contradicted some long-established common-sense notions about how the world works, but because they fit the evidence and passed the tests, they overcame initial skepticism to gain a firm place in the canon of accepted knowledge. Heated debate is ongoing in this field over several other fundamental issues, including the exact nature of dark matter and dark energy, the form of a grand unified theory, and what, if anything, came before the Big Bang; and other fields of science have their own debates as well. It is absurd to conclude that biology is the only field of science no longer amenable to change, not least because it has many areas of debate of its own. To name one example, fierce scientific debate is ongoing about the origin of life, but there are also present or recent past controversies centered around proposals such as punctuated equilibrium, the selfish gene, cladistics, group selection, mechanisms of speciation, human origins, and exact lines of descent in a variety of taxonomic groups. The evidence clearly shows that scientists in every field, including evolutionary biology, are more than willing to consider new ideas and evaluate them on their merits. The only rational conclusion is that creationism has been rejected not because of a scientific conspiracy, but because it simply isn’t true.
But even if this is the case, do the fact that scientists debate evolution mean that it is still a theory in crisis, as the creationists say? The answer is no, and to understand why, it is necessary to understand something about how science works. As should be obvious, a scientific theory’s success is evaluated based on how many natural phenomena it can successfully explain. The more observations a theory can tie together and account for in a consistent way, the more likely it is to be true; such a theory is said to be fertile, because it is good at generating explanations for previously unsolved mysteries and suggesting new directions in which to explore. In this respect, evolution has been a rousing success. Even a century and a half after it was first proposed, it continues to bring in new knowledge, and remains applicable and relevant in a wide range of areas. Debate is inevitable at the borders of our knowledge, where a successful theory is being extended to account for new phenomena. In this respect, healthy debate is the sign of a scientific theory’s strength, not its weakness, because it shows that that theory can still be successfully applied to unsolved questions, and that researchers are actively involved in doing this.
And, it cannot be stressed enough, no reputable scientist taking part in these debates – not even the ones that creationists love to quote out of context – doubts that evolution did occur. These debates are about aspects of how evolution works – what mechanisms drive it, and what specific results it has produced in particular times and places. That is all. The “big picture” – that all life is related in an ancient tree of common descent – is unaffected, and has only been strengthened by many years of scientific study that have shown again and again how robust and successful a theory evolution is. Any creationist attempt to imply otherwise should be dismissed as the sophistry that it is.