The term “consensus” has become a lightning rod in the public discussion of controversial areas of science. Scientists who were baffled that much of the public didn’t agree with scientific opinions on global warming and other controversial topics, began using the term as a means of ending all argument. By proclaiming the opinions to be “consensus science,” the scientific community intended to settle the argument. The response was quite the opposite. Many people interpreted this response to mean “we don’t have real evidence but we want you to trust us because we’re scientists and we said so.” Needless to say, the gulf between the scientific community and a skeptical public simply grew. “Consensus” for much of the public has become understood as a pre-determined agreement in the scientific establishment to proclaim a particular position, independent of any evidence and any opposition.
What does the scientific community really mean by the term? Consensus is a vital part of the scientific process. Consider three possible phases of scientific research. One is the frontier phase where a collection of observations has been made but there is no theory or paradigm whereby these observations might be understood. This is a creative period in which innovative ideas are explored. The next phase is one of controversy when one or more theories have been put forth but none has gained broad acceptance. This is an exciting period when different camps vie to gain acceptance for their theory. The pressure is on to obtain more data and find persuasive evidence. The third phase is the consensus phase, when enough evidence has been gathered that one of the competing theories has emerged as the accepted theory by all parties and the competitors have conceded. There is enough confidence in the theory for it to serve as a basis for future research, extending our understanding even further.
Science isn’t always that neat and orderly and these phases are not always clearly present. Nevertheless, the basic characteristic of consensus is the acceptance of a common paradigm or theory within which observations can be understood and on which further research can be based. Who determines whether this has been achieved? The key body of scientific literature is the technical peer reviewed literature. The researchers actively publishing in a particular field are the relevant community. The practice of peer-review and reliance on reproducibility by independent groups is vital to science. It is this community that determines consensus. The existence of other opinions from the public or by those with scientific training outside of this field is not pertinent. Alternative ideas and dissent need to be published and debated within the realm of the peer-reviewed literature.
At this point, someone invariably asks whether this practice doesn’t lead to an incestuous relationship in which contrarian views are arbitrarily, if not conspiratorially, rejected, thereby ensuring consensus. The reality of the scientific community is that it is comprised of numerous independently minded individuals and groups who are very competitive. None would miss an opportunity to point to a flaw in a proposed theory if they see a valid concern. One of the trademarks of science is the dependence on reproducibility by independent groups. This helps ensure that any subjective elements influenced by bias from any source are neutralized as much as possible. When groups of differing religious, political, and cultural perspectives all come to the same technical conclusions, the effect of bias is largely removed.
Consensus need not be unanimous. It is not unusual for a small minority of individuals or groups to persist in a contrarian view, sometimes in a very vocal and public manner. If the vast majority of the researchers publishing in this field have considered their views and shown why those contrarian views are not viable, then consensus has been achieved despite the public opposition. Skepticism needs to be published in the relevant technical journals before it is considered significant. Books and other non-peer reviewed media are not indicators of serious dissent.
The status of consensus science within the scientific community is of great importance. It conveys success in a highly competitive field with the top experts on that topic. It represents a level of understanding that qualifies the ideas as being a reliable foundation for future work. It is an eagerly sought achievement and is the goal of all research. It is therefore understandable that the scientific community sees the achievement of this status as a powerful argument for validity. Since the rise of modern scientific methods in the 19th century, seldom, if ever, has a consensus scientific opinion ever been subsequently shown to be false. Paradigms that have been overthrown are usually of untested assumptions and not of theories that have gained consensus through evidence based competition. Even classical mechanics was not shown to be false in its original realm of observation, but of more limited scope in application. No example of an overturned consensus science comes to mind.
For a public with minimal scientific literacy, however, the appeal to consensus has little meaning. It seems self-serving and arrogant. It is no wonder that rather than being persuaded, many people see evidence of a conspiracy to deny real evidence. A better approach for the scientific community is to continue to seek ways of presenting the data in such a manner that the public can understand. One of the biggest challenges for scientists is to learn how to communicate to a non-technical audience. It isn’t easy but when the stakes are high, the right communication is essential.