Debates about evolution in America typically take the form of a contest or conflict between two competing ideas, evolutionary theory and creationism. Because of this, it is generally assumed that the two are incompatible and mutually exclusive — an impression which scientific creationists are often quick to instill and perpetuate. Despite how much attention is given to conflicts between evolution and creationism, not everyone treats them as mutually incompatible.
Defining Creationism
Whether or not creationism and evolution contradict each other depends entirely upon what is meant by "creationism," an ambiguity which Evolution Deniers are able to exploit for political and religious purposes. You have to remember that denial of evolution is no more honest or reasonable than denial of plate tectonics or the germ theory of disease. This means that whatever an Evolution Denier tells you, you should treat it skeptically — even when they're telling you something that seems simple like that evolution contradicts creationism.
If by "creationism" we simple mean the belief that the universe, the world, and/or life itself was originally caused by God, gods, or other supernatural means, then creationism and evolution do not necessarily contradict. Any contradiction lies in the methodologies used to arrive at and defend the different positions, not in the details of the positions themselves.
Evolution has nothing to say about the origins of the universe, the world, or life itself. Evolution is about the development of life; a person can accept evolution as the best explanation for the diversity and development of life on Earth while also believing that the Earth and the life on it were first caused by God. The methodological contradictions might mean that this isn't a sensible combination, but there are no immediate and necessarily conflicts.
On the other hand, perhaps by "creationism" we mean a literal reading of the Book of Genesis from the Bible or some other ancient religious account of the origins and development of life on Earth. This is the type of creationism often adopted by those seeking to have it replace evolution in science classes and it does directly contradict evolution because they can't both be true and a person can't believe both simultaneously.
Evolution Denial as a Political Agenda
So why do some people use the general term "creationism" when they actually mean some very narrow and specific type of creationism? Many don't really believe that any other type of creationism is "real" or valid — in such cases, we can see that what they are doing is promoting their own specific religious vision and not the principle of scientific fair play which they tend to claim.
Others, however, are exploiting an ambiguity for their own purposes. Many people might call themselves "creationists" in the first and general sense without also adhering to the second and narrow sense. A scientific creationist who is trying to have his narrow ideas about religion and life taught in science classes can thus gain the support of those who do not necessarily support his beliefs.
Evolution Denial has nothing to do with genuine science or promoting science; instead, Evolution Denial is about promoting a political and religious agenda. As is common in politics and even sometimes religion, ambiguous terminology is used to make a position appear more attractive, to make a position appear more popular, or even to allow a position mean different things to different people.
Political goals are pursued with political tactics and political ethics but because this debate involves science, too many implicitly assume that perhaps basic scientific standards of accuracy, precision, and reasonableness are being employed. Don't make this mistake; instead, question what you hear and treat claims with careful skepticism.
