Aspects of Scientific Consensus

Chris Haufe (Case Western Reserve University)
I propose to model scientific consensus as a population-level state akin to fixation in population genetics. Using this analogy, we can derive a variety of interesting theses regarding the nature of scientific consensus and the processes which lead to it. We can then use these theses as guidance for how to understand the normative significance of scientific consensus within science. Finally, we can connect these normative lessons regarding scientific knowledge with broader themes in normative epistemology.

John Beatty (University of British Columbia)
One might think that aiming for consensus in a group would be aiming for the agreement of all, or at least a high proportion of its members. But that's not what "consensus" means in the case of the IPCC, nor in many other decision-making settings where it's less about everyone agreeing, and more about no one openly objecting. Which are very different. Whatever the merits of such "no-objection" procedures they do have one serious epistemic downside: they leave much unsaid about the viewpoints of the individual group members - like the extent to which they agree or disagree.

Kristin Schaupp (University of Wisconsin-Eau Claire)
Recent philosophical work on disagreement and consensus provides insight into how apparent consensus proceedings can mask disagreement. I demonstrate the undeniable impact that decision-making procedures have by examining the events leading up to the explosion of NASA's Space Shuttle Challenger. I argue that this not only allows us to gain a more complete understanding of what led to the disastrous decision to launch the Challenger, but it also shows us that an apparent consensus approach can conceal even substantial dissent. This, in turn, illustrates why the identification of potential abuses of apparent consensus proceedings is crucial for good scientific practice.

Miriam Solomon (Temple University)
Medicine, including psychiatry, is an applied science. Consensus is more important in applied sciences than in basic research, because contexts of application require some common understanding to engage in joint action and justify it to the rest of society. Psychiatry lags behind other medical disorders in its understanding of causes and mechanisms. Many, both inside and outside of philosophy, (e.g. Dominic Murphy, Thomas Insel) have called for a psychiatric nosology that is more explanatory than our current descriptive account, and maybe that will be available in the future. At this time, what we have is the DSM and the ICD, both "consensus statements" in wide usage. The DSM and ICD largely overlap in the classification of psychiatric diseases, defining disease categories through descriptions of typical behaviors and symptoms. A consensus statement is an explicit summary of the state of knowledge in a field, intended to be authoritative both within a field and outside the field. DSM-III (1980) was the first such consensus statement for psychiatry, and DSM-5 (2013) is the most recent. My talk will ask the following questions: How is the DSM updated? And how should it be updated? DSM-5 had thirteen Work Groups, each assigned to make updates in one area of psychiatry. Work Group recommendations were reviewed by higher level committees including the Scientific Research Committee, the Clinical and Public Health Committee, the DSM-5 Task Force, and finally by the American Psychiatric Association Board of Trustees. The overall structure was one of hierarchically arranged expert consensus conferences. The Scientific Research Committee focused on reviewing the evidence for changes and the Clinical and Public Health Committee checked broader implications of change (for health care reimbursement, education, the law, etc.). I will argue that the concerns of the Scientific Research Committee were raised too late in the process to have the appropriate impact on group decision making. Experience with medical consensus conferences suggests that an evidence assessment should take place before the first Work Group assembles. Furthermore, there are specific challenges with what should count as an "evidence assessment" when what is being assessed is a nosology, rather than the effectiveness of a health care intervention (as is typical in evidence-based medicine). There are a variety of kinds of evidence relevant to psychiatric classifications (e.g. genetic studies, imaging studies, biological marker studies, diagnostic stability, common responsiveness to treatments), and most of them do not fit into the typical hierarchy of clinical trials used in evidence-based medicine. I will make some suggestions for how to aggregate this more heterogeneous evidence. Finally, I will argue that the concerns of the Clinical and Public Health Committee should be addressed by inviting experts in other fields (law, health care economics, ethics, education), as well as patient representatives, to participate in Work Groups.

Matthew Slater (Bucknell University), Joanna Huxster (Eckerd College)
It is well known that large segments of the American lay public do not see anthropogenic climate change (ACC) as a serious risk. Recent social scientific research on climate change communication has suggested that acceptance that there is a scientific consensus about ACC may serve as a "gateway belief" for more accurate belief about its existence and risks. We argue that such messages only gain their permanence and utility in a context of an understanding of the social structure of science that makes the epistemic significance of scientific consensus understandable. How best should we convey such an understanding?