Consensus is not Science

We often hear the term “scientific consensus” these days. The word “consensus” means that a group of people is in “general agreement” about some proposition or belief: I quote “general agreement” because the definition is fuzzy about just how many dissenters there can be within the group. For scientists, this proposition or belief usually concerns the validity of some theory and the term scientific consensus means that there is a general agreement among scientists that a theory is the “leading” or “best” theory. An example usage would be, “The scientific consensus is that natural selection is the prime mechanism for evolution”.

But science itself is not about consensus; science is about discovering and describing reality. Reality is what it is regardless of what theories exist and who believes these theories. Scientists know this and have developed a method, the “scientific method”, to go about validating theories and grounding them in reality. And the scientific method does not make any use of consensus. The scientific method is about testing theories with experiments, investigation, and observation. This is done over and over, by different people at different times, with greater and greater accuracy. This process continues even when just about every scientist believes a theory to be “good”. As an example, there are still experiments today testing the theory of general relativity, even though after almost 100 years of experimentation, no experiment (after repetition) has shown a contrary result. Consensus has nothing to do with it.

So if science is not about consensus why do we see the term “scientific consensus” so often? The answer is that consensus is a political word and it is used for political purposes. When used in the public arena, the term “scientific consensus” is used to try and persuade others that some belief is true and that some action is needed: usually a regulatory action or a funding decision. When you hear this term used in the media or in the public arena you can be sure that the writer or speaker is making or refuting a political point or trying to sell something. Even a scientist talking about consensus in a public forum would be speaking as a politician or salesmen, not as a scientist. The reason is that any scientist would know that no scientist would base her scientific judgments on anything other than the scientific method.

Lately, we've seen the term applied to global warming. Al Gore and others would like to persuade us that human activity is causing global warming which will likely lead to catastrophic consequences for life on Earth. To this end we are told that there is “scientific consensus” and that the “time for debate is over”. For any real scientist engaged in science, the first statement is irrelevant and the second ludicrous. Even if a scientist agreed with the anthropomorphic theory of global warming (as many do), she would never say that other theories shouldn't be explored or that her theory doesn't need to be tested. And if she was a good scientist and her favorite theory didn't agree with observation, it wouldn't make one bit of difference that there was a consensus behind the theory, it would be time for a new theory.