This paper develops a formal framework to model a process in which the formation of individual opinions is embedded in a deliberative exchange with others. The paper opts for a low-resolution modeling approach and abstracts away from most of the details of the social-epistemic process. Taking a bird's eye view allows us to analyze the chances for the truth to be found and broadly accepted under conditions of cognitive division of labour combined with a social exchange process. Cognitive division of (...) labour means that only some individuals are active truth seekers, possibly with different capacities. Both mathematical tools and computer simulations are used to investigate the model. As an analytical result, the Funnel Theorem states that under rather weak conditions on the social process, a consensus on the truth will be reached if all individuals possess an arbitrarily small capacity to go for the truth. The Leading the pack Theorem states that under certain conditions even a single truth seeker may lead all individuals to the truth. Systematic simulations analyze how close agents can get to the truth depending upon the frequency of truth seekers, their capacities as truth seekers, the position of the truth (more to the extreme or more in the centre of an opinion space), and the willingness to take into account the opinions of others when exchanging and updating opinions. (shrink)

When does opinion formation within an interacting group lead to consensus, polarization or fragmentation? The article investigates various models for the dynamics of continuous opinions by analytical methods as well as by computer simulations. Section 2 develops within a unified framework the classical model of consensus formation, the variant of this model due to Friedkin and Johnsen, a time-dependent version and a nonlinear version with bounded confidence of the agents. Section 3 presents for all these models major analytical results. Section (...) 4 gives an extensive exploration of the nonlinear model with bounded confidence by a series of computer simulations. An appendix supplies needed mathematical definitions, tools, and theorems. (shrink)

The paper defends the thesis that institutional virtue is properly modeled as a ‘‘consensual’’ property, along the lines of the Lehrer–Wagner model of consensus (LWC). In a first step, I argue that institutional virtue is not exhausted by duty-fulfilling, since institutions, contrary to natural individuals, are designed to fulfill duties. To avoid the charge of vacuity, virtue, if attributed to institutions, must be able to motivate supererogatory action. In a second step, I argue against dis- continuity of institutional virtue with (...) individual virtue. Two main arguments for discontinuity of collective properties display serious shortcomings when applied to virtues of institutions. Given that motivation for supererogatory action is neither inferred from statutory duties nor accommodates a right of reprobation, modeling institutional virtue on collective rationality or explaining it in terms of joint com-mitment both prove problematic. In a third step, I argue that LWC has the explanatory potential to account for institutional virtue. Due to its main features,iteration and evaluation, it provides a non-trivial analysis of continuity and thereby satisfies basic constraints on the notion of genuine institutional virtue. (shrink)

The following is a defense of Jurgen Habermas' argumentational consensual procedure against Keith Lehrer and Carl Wagner's weighted averaging consensual procedure (and, I tentatively claim, against any weighted averaging consensual procedure). The argument is twofold: if Lehrer and Wagner intend, implicity, to replace what is for Habermas the metatheoretical stage of a discussion with the aggregation of judgments of respect, then their procedure fails to make use of all available information and the participants are not committed to the weighted average (...) position on these grounds; if, on the other hand, they do not intend to replace metatheoretical discussion by aggregation, then the conditions under which the discussion could conceivably have come to a halt are such as to provide no support for the claim that it is rational to aggregate, rather than to consider the discussion unresolved until more information is available. (shrink)