Consensus

Consensus in the English language is defined firstly as unanimous or general agreement; and secondly group solidarity of belief or sentiment.

Idyllically, achieving consensus requires serious treatment of every group member's considered opinion. Those who wish to take up some action want to hear those who oppose it, because they count on the fact that the ensuing debate will improve the consensus. Action without resolution of considered opposition will be rare and done with attention to minimize damage to relationships.

Consensus as collective thought

A close equivalent phrase might be the "collective agreement" of a group, keeping in mind that a high degree of variation is still possible among individuals, and certainly if there must be individual commitment to follow up the decision with action, this variation remains important. There is considerable debate and research into both collective intelligence and consensus decision-making.

This article focuses strictly on the idea of consensus in the abstract, not on the implications of consensus for politics or economics, where follow-up action is required.

Consensus usually involves collaboration, rather than compromise. Instead of one opinion being adopted by a plurality, stakeholders are brought together (often with facilitation) until a convergent decision is developed. If this is done in a purely mechanical way it can result in simple trading—we'll sacrifice this if you'll sacrifice that. Genuine consensus typically requires more focus on developing the relationships among stakeholders, so that they work together to achieve agreements based on willing consent.

Models of consensus

The most common and most successful model of consensus is called the prisoner's dilemma. An introduction and discussion of this concept can be found in any contemporary introduction to political science. This approach might be called "algebraic" as opposed to analytic, within mathematics, because it represents an agent by a symbol and then examines the algebraic properties of that symbol. For example, the question, "Can two agents be combined to make a new agent?" sounds like an algebraic question. (More formally, "is the operation of consensus closed in the domain of agents? Is there a larger domain of "abstract agents" in which this operation is closed?")

In a more analytic style, we might naively start by envisioning the distribution of opinions in a population as a Gaussian distribution in one parameter. We would then say that the initial step in a consensus process would be the written or spoken synthesis that represents the range of opinions within perhaps three standard deviations of the mean opinion. Other standards are possible, e.g. two standard deviations, or one, or a unanimity minus a certain tolerable number of dissenters. The following steps then operate both to check understanding of the different opinions (parameter values), and then to find new parameters in the multi-dimensional parameter space of all possible decisions, through which the consensus failure in one-dimensional parameter space can be replaced by a solution in multi-dimensional parameter space.

An alternative, qualitative, mathematical description is to say that there is an iterative process through (m+n)-dimensional parameter space, starting from initial guesses at a solution in (m)-dimensional parameter space, which tries to converge to find a common solution in (m+n)-dimensional parameter space.

A criticism of such modeling is that the opinions or agreements are only theoretical, and that the strength or degree of conviction as measured is not closely correlated to the willingness of any given individual to take action. In direct action politics, the consensus is constantly tested by asking those who agree to immediately place their own bodies 'on the line' and in harm's way, to actually demonstrate that they are committed to a consensus. The ecology movement, peace movement, and labor movement have historically required such demonstrations of commitment. Some have disdained any attempt at formal models or methods, but others have prepared extensive documentation on both formal and informal consensus decision-making processes.

Typically, the usefulness of formal models of consensus is confined to cases where follow up action is closely and centrally controlled, e.g. in a military hierarchy or a set of similar computer programs executing on hardware that it completely controls. The idea of consensus itself is probably quite different when considering action by a group of independent human agents, or considering action by those taking orders and committed to executing them all without question, or suffering great harm or exile for any disobedience.

Consensus upon a particular formal model of consensus can lead to groupthink, by making it harder for those who reject that formal model (and using informal or different models) to be heard. This recursion suggests the extreme complexity of reasoning about consensus in a political context. An example is the peace movement's objection to the game theory logic of mutual assured destruction during the Cold War. Peace activists, objecting to military goals and spending found the formal models of the military to be major obstacles. As they had not mastered game theory models they simply were not heard.

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