Predictable polarization is everywhere: we can often predict how people’s opinions, including our own, will shift over time. Extant theories either neglect the fact that we can predict our own polarization, or explain it through irrational mechanisms. They needn’t. Empirical studies suggest that polarization is predictable when evidence is ambiguous, that is, when the rational response is not obvious. I show how Bayesians should model such ambiguity and then prove that—assuming rational updates are those which obey the value of evidence—ambiguity (...) is necessary and sufficient for the rationality of predictable polarization. The main theoretical result is that there can be a series of such updates, each of which is individually expected to make you more accurate, but which together will predictably polarize you. Polarization results from asymmetric increases in accuracy. This mechanism is not only theoretically possible, but empirically plausible. I argue that cognitive search—searching a cognitively accessible space for a particular item—often yields asymmetrically ambiguous evidence, I present an experiment supporting its polarizing effects, and I use simulations to show how it can explain two of the core causes of polarization: confirmation bias and the group polarization effect. (shrink)

The "myside bias'' in evaluating arguments is an empirically well-confirmed phenomenon that consists of overweighting arguments that endorse one's beliefs or attack alternative beliefs while underweighting arguments that attack one's beliefs or defend alternative beliefs. This paper makes two contributions: First, it proposes a probabilistic model that adequately captures three salient features of myside bias in argument evaluation. Second, it provides a Bayesian justification of this model, thus showing that myside bias has a rational Bayesian explanation under certain conditions.

The my-side bias is a well-documented cognitive bias in the evaluation of arguments, in which reasoners in a discussion tend to overvalue arguments that confirm their prior beliefs, while undervaluing arguments that attack their prior beliefs. The first part of this paper develops and justifies a Bayesian model of myside bias at the level of individual reasoning. In the second part, this Bayesian model is implemented in an agent-based model of group discussion among myside-biased agents. The agent-based model is then (...) used to perform a number of experiments with the objective to study whether the myside bias hinders or enhances the ability of groups to collectively track the truth, that is, to reach the correct answer to a given binary issue. An analysis of the results suggests the following: First, whether the truth-tracking ability of groups is helped or hindered by myside bias crucially depends on how the strength of myside bias is differentially distributed across subgroups of discussants holding different beliefs. Second, small groups are more likely to track the truth than larger groups, suggesting that increasing group size has a detrimental effect on collective truth-tracking through discussion. (shrink)

A longstanding assumption within higher education is that there is a clear link between argumentative writing and critical thinking. In this paper, I challenge this assumption. I argue that argumen...

The desire to maintain current beliefs can lead individuals to evaluate contrary evidence more critically than consistent evidence. We test whether priming individuals’ scientific reasoning...

Mercier & Sperber (M&S) argue for their argumentative theory in terms of communicative abilities. Insights can be gained by extending the discussion beyond human reasoning to rodent and robot navigation. The selection of arguments and conclusions that are mutually reinforcing can be cast as a form of abductive reasoning that I argue underlies the construction of cognitive maps in navigation tasks.

Short abstract (98 words). Reasoning is generally seen as a means to improve knowledge and make better decisions. However, much evidence shows that reasoning often leads to epistemic distortions and poor decisions. This suggests that the function of reasoning should be rethought. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given humans’ exceptional dependence on communication and vulnerability to misinformation. A wide range of (...) evidence in the psychology of reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. (shrink)

A plausible view in the literature on the epistemic condition of blameworthiness is the Reasonable Expectation View (RE). According to RE, whether ignorance excuses an agent from deserving blame is a matter of whether the agent could have reasonably been expected to have avoided or corrected the ignorance. This paper does not take up the task of defending this view, but instead examines what it implies for an interesting type of ignorance: moral or political ignorance rooted in myside bias. With (...) the prevalence of increasing political polarization, it is worth examining what a plausible view like RE implies about when, if ever, myside bias-based ignorance excuses the agent from blame—from deserving resentment or indignation. To assess this issue, the paper examines the empirical literature on what it takes to mitigate myside bias and then takes the United States as a case study to examine what RE implies for the actual non-ideal circumstances many agents are in. The paper argues that RE has two revisionary implications for our practice of blame. First, the paper argues that RE implies that political or moral ignorance rooted in myside bias is currently an excuse in a surprising number of cases. Second, our epistemic position to know whether a given instance of political or moral ignorance is excusing is often inadequate. (shrink)

This special issue of Informal Logic brings together a num-ber of traditions from the psychology and philosophy of argument. Psycho-logists’ interest in argument typically arises in understanding how indivi-duals form and change their beliefs. Thus, theories of argument can serve as models of the structure of justi-fications for belief, as methods of diagnosing errors in beliefs, and as prototypes for learning. The articles in this issue illustrate all three of these connections.

Having defended the usefulness of our definition of reasoning, we stress that reasoning is not only for convincing but also for evaluating arguments, and that as such it has an epistemic function. We defend the evidence supporting the theory against several challenges: People are good informal arguers, they reason better in groups, and they have a confirmation bias. Finally, we consider possible extensions, first in terms of process-level theories of reasoning, and second in the effects of reasoning outside the lab.

Mercier & Sperber (M&S) claim that the phenomenon of belief bias provides fundamental support for their argumentative theory and its basis in intuitive judgement. We propose that chronometric evidence necessitates a more nuanced account of belief bias that is not readily captured by argumentative theory.

The empirical research on the psychology of argumentation suggests that people are prone to fallacies and suboptimal performance in generating, comprehending, and evaluating arguments. Reasoning and argumentation are interrelated skills that use many of the same cognitive processes. The processes we use to convince others are also used to convince ourselves. Argumentation would be ineffective if we couldn't reason for ourselves.

Being able to discriminate poorly justified from well justified arguments is necessary for informed citizenship. However, it is not known whether the ability to recognize argument strength generalizes across different types of arguments, and what cognitive factors predict this ability or these abilities. Drawing on the theory of argument schemes, we examined arguments from consequence, analogy, symptoms, and authority in order to cover all major types of arguments. A study (_N_ = 278) on the general population in Finland indicated that (...) the ability to discriminate between strong and weak arguments did not differ between these schemes. Argument strength discrimination ability correlated positively with analytic thinking dispositions promoting both quality and quantity of thinking, slightly positively with education, and negatively with overconfidence. It was unrelated to an intuitive thinking style, and to self-rated mental effort. (shrink)