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Logical Models of Informational Cascades

Baltag, Alexandru; Christoff, Zoé; Hansen, Jens Ulrik LU and Smets, Sonja (2013) In Logic Across the University: Foundations and Applications p.405-432
Abstract
In this paper, we investigate the social herding phenomenon known as informational cascades, in which sequential inter-agent communication might lead to epistemic failures at group level, despite availability of information that should be sufficient to track the truth. We model an example of a cascade, and check the correctness of the individual reasoning of each agent involved, using two alternative logical settings: an existing probabilistic dynamic epistemic logic, and our own novel logic for counting evidence. Based on this analysis, we conclude that cascades are not only likely to occur but are sometimes unavoidable by "rational" means: in some situations, the group’s inability to track the truth is the direct consequence of each... (More)
In this paper, we investigate the social herding phenomenon known as informational cascades, in which sequential inter-agent communication might lead to epistemic failures at group level, despite availability of information that should be sufficient to track the truth. We model an example of a cascade, and check the correctness of the individual reasoning of each agent involved, using two alternative logical settings: an existing probabilistic dynamic epistemic logic, and our own novel logic for counting evidence. Based on this analysis, we conclude that cascades are not only likely to occur but are sometimes unavoidable by "rational" means: in some situations, the group’s inability to track the truth is the direct consequence of each agent’s rational attempt at individual truth-tracking. Moreover, our analysis shows that this is even so when rationality includes unbounded higher-order reasoning powers (about other agents’ minds and about the belief-formation-and-aggregation protocol, including an awareness of the very possibility of cascades), as well as when it includes simpler, non-Bayesian forms of heuristic reasoning (such as comparing the amount of evidence pieces). (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
Logic Across the University: Foundations and Applications
editor
van Benthem, Johan and Lui, Fenrong
pages
405 - 432
publisher
College Publications
ISBN
978-1-84890-122-3
project
Collective Competence in Deliberative Groups: On the Epistemological Foundation of Democracy
language
English
LU publication?
yes
id
f3c0e4e8-069d-4d0e-ad76-91e6fa9d7ba2 (old id 4025315)
date added to LUP
2013-09-19 16:27:35
date last changed
2016-04-16 08:48:00
@inbook{f3c0e4e8-069d-4d0e-ad76-91e6fa9d7ba2,
  abstract     = {In this paper, we investigate the social herding phenomenon known as informational cascades, in which sequential inter-agent communication might lead to epistemic failures at group level, despite availability of information that should be sufficient to track the truth. We model an example of a cascade, and check the correctness of the individual reasoning of each agent involved, using two alternative logical settings: an existing probabilistic dynamic epistemic logic, and our own novel logic for counting evidence. Based on this analysis, we conclude that cascades are not only likely to occur but are sometimes unavoidable by "rational" means: in some situations, the group’s inability to track the truth is the direct consequence of each agent’s rational attempt at individual truth-tracking. Moreover, our analysis shows that this is even so when rationality includes unbounded higher-order reasoning powers (about other agents’ minds and about the belief-formation-and-aggregation protocol, including an awareness of the very possibility of cascades), as well as when it includes simpler, non-Bayesian forms of heuristic reasoning (such as comparing the amount of evidence pieces).},
  author       = {Baltag, Alexandru and Christoff, Zoé and Hansen, Jens Ulrik and Smets, Sonja},
  editor       = {van Benthem, Johan and Lui, Fenrong},
  isbn         = {978-1-84890-122-3},
  language     = {eng},
  pages        = {405--432},
  publisher    = {College Publications},
  series       = {Logic Across the University: Foundations and Applications},
  title        = {Logical Models of Informational Cascades},
  year         = {2013},
}