Assessing the impact of deliberation on people's votes

Guilty or innocent? In a famous American film, 12 jurors deliberate the fate of a man accused of murder. If they find him guilty, he’ll end up in the electric chair. If they have valid doubts, the man will be acquitted. The first vote was by a show of hands: 11 jurors found him guilty. But Juror 8 has his doubts. In the stifling heat of the jury room, a long and difficult debate begins. Throughout the film, arguments, and votes follow one another, with voting procedures varying. At the end of the process, the jurors reach a verdict of not guilty by reasonable doubt. So what happened? Is the difference in verdicts the consequence of discussion, or is it due to the change in voting methods? Beyond the cinema screen, does deliberation offer a solution for creating a consensus based on the elimination of poor arguments? This is precisely the type of question that the team of researchers Mariam Maki Sy, Charles Figuières, Helene Rey-Valette, Richard Howarth and Rutger de Wit have been looking into. 

About us

Dialogues économiques is a digital magazine published by the Aix-Marseille School of Economics (AMU, CNRS, EHESS, Centrale Méditerranée) A bridge between academic research and society, Dialogues économiques provides all citizens with the keys to economic reasoning. Articles are published every two weeks.

The researchers wondered whether the choice of tools used to synthesize participants' opinions during a collective deliberation had an impact on the outcome of that deliberation.

The black box of deliberative democracy

The stakes are high. Since the 1980s, the growing disaffection of citizens with representative democracy has led to the encouragement of new forms of participation. The use of decision-making processes based on exchange and discussion is increasingly popular. This deliberative democracy seems more likely to produce solutions that serve the common good and are supported by the population. In France, a recent example is the Citizens' Climate Convention, made up of citizens drawn by lot. At the outset, these citizens had a wide range of ideas about the climate policies they wanted to see implemented. However, after debate, the 149 proposals drawn up by the various "commissions" were adopted by all the members of the Convention by near consensus.

Now that collective deliberation is being encouraged, it is important to understand how it works and to avoid possible abuses or perverse effects. Researchers in political science, for example, have studied the conditions for inclusive and fair deliberation in societies marked by inequalities and relationships of domination. This work focused on the modalities of the debates themselves. For example, how can we ensure that no one takes over the floor during discussions? But until now, no one has looked at the way in which participants' opinions are aggregated. However, every deliberation explicitly or implicitly uses a method to summarise the opinions of the participants. This is what social choice theory, which studies the processes involved in arriving at a coherent collective decision, calls a "social preference".

One vote does not equal one vote

For a long time now, this theory of social choice has shown that voting methods are not equivalent to one another. For example, for a presidential election, organising a two-round majority vote or asking voters to rate all the candidates and then aggregating the ratings can lead to divergent results. And at the risk of killing any suspense, you should know that there is no ideal method, but rather a multiplicity of methods, each with its own qualities and faults. Studies of collective deliberation have been surprisingly silent on this dimension: the aggregation methods used to measure the impact of deliberation are rarely explained. However, we can assume that the choice of method influences the result obtained. For example, we know that deliberations can lead to the amplification of a previously dominant opinion - this is known as the polarisation effect. This tempers the optimistic message of the film "12 Angry Men", in which deliberation ultimately leads to the evolution of the jurors' decision.