The Social Epistemology of Consensus and Dissent

Abstract

This paper reviews current debates in social epistemology about the relations between knowledge and consensus. These relations are philosophically interesting on their own, but also have practical consequences, as consensus takes an increasingly significant role in informing public decision making. The paper addresses the following questions. When is a consensus attributable to an epistemic community? Under what conditions may we legitimately infer that a consensual view is knowledge-based or otherwise epistemically justified? Should consensus be the aim of scientific inquiry, and if so, what kind of consensus? How should dissent be handled? It is argued that a legitimate inference that a theory is correct from the fact that there is a scientific consensus on it requires taking into consideration both cognitive properties of the theory as well as social properties of the consensus. The last section of the paper reviews computational models of consensus formation. Consensus plays an increasingly growing role in public life. The National Institute of Health (NIH) and the Intergovernmental Panel on Climate Change (IPCC) formulate expert consensus statements to provide authoritative answers to disputed questions. The “Danish Citizen Consensus Model” is used for assessing societal dimensions of science and technology (Medlock et al, 2007; Horst 2008; Einsiedel et al. 2001). Wikipedia promotes consensus for achieving neutrality and verifiability (Wikipedia 2017). Scientific consensus is deferred to when arbitrating between rival experts in legal trials. But when we think about the relations between knowledge and consensus, two conflicting intuitions arise. On the one hand, since when is truth determined by numbers? Are we back to the notorious Indiana House of Representatives “Pi Bill” of 1897, which redefined Pi by majority voting? (Hallerberg 1977) Wasn’t Galileo right although his views contradicted common wisdom? On the other hand, for every Galileo, there are hundreds of misguided contrarians, forgotten by history. Is everybody wrong and only you are right? Current social epistemology of consensus and dissent sorts out these conflicting intuitions. 1 Social epistemologists distinguish between knowledge-based consensus and mere agreement, explore the relations between consensus and the aims of inquiry, and distinguish legitimate from illegitimate dissent. Section 1 concerns the attribution of consensus to an epistemic community. Section 2 reviews accounts of knowledge-based or epistemically justified consensus. Section 3 addresses consensus as an aim of inquiry and the normative status of dissent. Section 4 reviews computational models of consensus. 1. When Does a Consensus Exist? Deciding whether a consensus exists is not always trivial. To do so, we need to assess the scope of and depth of the agreement. Start with scope. Tucker (2003, 509-510) argues that a 1 In philosophy of science until the early 1980s, scientific consensus was addressed mostly in the context of Kuhn’s (1962/1970) The Structure of the Scientific Revolutions (See Wray in this volume). For a classic account of the interplay between data, theory, method, and rational consensus, see Laudan (1984).