Collective Intelligence through Aggregation

[Christian List]

Dear Colleagues,

 

I’m writing to circulate my paper with Franz Dietrich, “Collective Intelligence through Aggregation”, in Philosophical Transactions of the Royal Society B, which might be of interest to some of you, especially those with interests in judgment aggregation and social choice theory.

 

The paper is available here (open access):

https://doi.org/10.1098/rstb.2024.0454

 

I append an abstract at the bottom.

 

Best wishes

Christian List

 

Christian List

Munich Center for Mathematical Philosophy

LMU Munich

https://christianlist.net

 

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Abstract: Suppose a committee, expert panel or other group is making judgements on some issues, where these may be not just yes/no questions, such as whether a defendant is guilty, but also variables with many possible values, such as macroeconomic or meteorological variables or travel directions. Furthermore, there may be interconnections between different issues, as in the case of economic or climate variables. How can the group arrive at ‘intelligent’ collective judgements, based on the group members’ individual judgements? We investigate three challenges raised by this judgement-aggregation problem. First, reasonable methods of aggregation (such as defining the collective judgement for each issue as the average or median judgement) can produce inconsistent collective judgements. Second, many methods of aggregation are manipulable by strategic voting. Finally, not all methods of aggregation are conducive to tracking the truth on the issues in question. We prove new impossibility or possibility theorems on all three challenges, identifying what it takes to produce collective judgements in a consistent, non-manipulable and truth-tracking manner and thereby to achieve collective intelligence through aggregation. Overall, the median method, though imperfect, performs reasonably well. We also note the relevance of our analysis for non-human group decisions.

 

[Attila Ambrus]

Dear Christian, I have a paper published in the Journal of Public Economics, with Ben Greiner and Parag Pathak, experimentally investigating the role of the median group member in group decision-making, albeit in the context of non-intellective tasks. In particular we point out that the median group member having a strong influence on the group decision explains many observed "group shifts" (systematic differences between group and individual decisions in the same decision problems) if the distribution of individual opinions is skewed. Again, our paper is in the realm of non-intellective tasks (preference aggregation), so I'm not sure if it's related enough, but just in case here is a link to the paper:

https://public.econ.duke.edu/~aa231/paper_groups-4.pdf

Best,

Attila Ambrus

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