What is scientific consensus, and how do we achieve it?

By Melissa Burt  |  May 15, 2020

The first-year IGC seminar students discussed the challenges of reaching “scientific consensus” with Dr. Julia Gohlke(Associate Professor in Population Health Sciences), who shared her experiences working on panels to determine scientific consensus on health impacts of the Deepwater Horizon oil spill in the Gulf of Mexico.

“Scientific consensus” is the view held by most scientists specialized in that field. But how is it generated? To see how scientific consensus is reached, we focused on the processes used by the IPCC and the NAS. Both groups start their process by determining the scope of the problem that requires scientific consensus. For IPCC, this is determined by the governments leading the United Nations, while for the NAS this is determined by boards within the NAS and those sponsoring specific studies. The next step for both groups is to establish a group of scientists that specialize within that scope that will collect and assess the body of scientific evidence on the topic. During this process, those scientists meet and determine where the scientific evidence leads to agreement. For example, the IPCC panels examine the current science of climate change and determine to what extent the scientific evidence points towards human activity as a cause. Once the lead scientists determine their consensus on a given topic and write a report summarizing the evidence, the report then is peer-reviewed by other scientists before being finalized and communicated to the sponsors of the study.

We finished up our discussion on scientific consensus by focusing on the potential pros and cons of this process. Some pros of consensus building include that the process incorporates the expertise of scientists, is typically transparent process (i.e. the process of the IPCC and NAS are publicly available), and synthesizes a potentially broad array of pieces of evidence. Because the scientists are tasked with determining areas of agreement, the output of the process can be a clear picture of where the experts agree potentially providing a clear path for how to incorporate scientific evidence into the decision process of policy makers. On the other hand, this can go in the opposite direction when scientists cannot find consensus potentially leading to scientific evidence being left out of decision making or the erosion of public confidence in scientists. Another potential con of consensus building is that it requires a majority of scientists on a topic to agree which means some viewpoints may be left out. Finally, although scientists might aspire to objectivity in this process of consensus building, biases can still enter into the process either with unconscious or unacknowledged biases on the part of the scientists or when it comes to applying the synthesis of scientific evidence to policy decisions. Overall, while we could point out these potential pitfalls of consensus building, we found it difficult to come up with alternative processes to incorporating science into policy decisions.

Melissa Burt is a PhD student in Dr. Susan Whitehead’s Lab in Biological Sciences. She is studying how seed dispersal mutualisms respond to habitat fragmentation and climate change.

Header photo credit: IPCC

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