Confirmation bias is one of the most widely discussed epistemically problematic cognitions, challenging reliable belief formation and the correction of inaccurate views. Given its problematic nature, it remains unclear why the bias evolved and is still with us today. To offer an explanation, several philosophers and scientists have argued that the bias is in fact adaptive. I critically discuss three recent proposals of this kind before developing a novel alternative, what I call the 'reality-matching account'. According to the account, confirmation bias evolved because it helps us influence people and social structures so that they come to match our beliefs about them. This can result in significant developmental and epistemic benefits for us and other people, ensuring that over time we don't become epistemically disconnected from social reality but can navigate it more easily. While that might not be the only evolved function of confirmation bias, it is an important one that has so far been neglected in the theorizing on the bias.

Members of the field of philosophy have, just as other people, political convictions or, as psychologists call them, ideologies. How are different ideologies distributed and perceived in the field? Using the familiar distinction between the political left and right, we surveyed an international sample of 794 subjects in philosophy. We found that survey participants clearly leaned left (75%), while right-leaning individuals (14%) and moderates (11%) were underrepresented. Moreover, and strikingly, across the political spectrum from very left-leaning individuals and moderates to very rightleaning individuals, participants reported experiencing ideological hostility in the field, occasionally even from those on their own side of the political spectrum. Finally, while about half of the subjects believed that discrimination against leftor right-leaning individuals in the field is not justified, a significant minority displayed an explicit willingness to discriminate against colleagues with the opposite ideology. Our findings are both surprising and important because a commitment to tolerance and equality is widespread in philosophy, and there is reason to think that ideological similarity, hostility, and discrimination undermine reliable belief formation in many areas of the discipline.

Endogenous or physically conditioned psychoses are usually considered to be the underlying cause of signs of extreme self-neglect and social retreat if these occur suddenly in persons who had been socially successful up to that time. However, in recent years several independent researchers have found extreme sociocultural refusal attitudes even in patients not displaying any psychotic disturbances. This unexpected result led to a new syndrome concept which has since been accepted internationally under the designation "Diogenes syndrome". Hence, the Diogenes syndrome comprises shameless neglect of body and personal environment, associated with collectionism, social retreat and rejection of any well-meant help. It has been reported that this constellation of signs allegedly occurs with enhanced frequency in women over 60 years of age with self-isolation tendencies in their previous life history. The following article reviews the literature published so far on the Diogenes syndrome and presents two cases treated by the authors, as a suitable means to re-examine and to define the new syndrome concept more precisely. The following conclusions can be drawn from the cases already reported in the literature and the two cases newly presented here: The socioculturally complete rejection associated with the Diogenes syndrome is the final result of a personality-based abnormal emotional reaction development. Marked seclusion tendencies in the previous life history, as well as organic brain diseases, are relevant. Medical treatment can be successful mainly by means of behaviour therapy techniques.

The proposal that values in science are illegitimate and that they should be counteracted whenever they direct inquiry to the confirmation of predetermined conclusions is not uncommon in the philosophy of science. Drawing on recent research from cognitive science on human reasoning and confirmation bias, I argue that this view should be rejected. Values that drive inquiry to the confirmation of predetermined conclusions can contribute to the reliability of scientific inquiry at the group level, even when they negatively affect an individual’s cognition. This casts doubt on the proposal that such values should always be illegitimate in science. It also suggests that this proposal assumes a narrow, individualistic account of science that threatens to undermine the project of ensuring reliable belief-formation in science. 1Introduction2Advocates of the Confirmatory Value View3Versions of the Confirmatory Value View4Mandevillian Cognition and Why It Matters in Science4.1Recent research on human reasoning and confirmation bias4.2Mandevillian confirmation bias in science4.3Situating the argument5Against the Confirmatory Value View5.1Qualifications and clarifications5.2An objection: The dogmatism problem6Conclusion

Introduction Sources of infection of most cases of community-acquired Legionnaires’ disease (CALD) are unknown. Objective Identification of sources of infection of CALD. Setting Berlin; December 2016–May 2019. Participants Adult cases of CALD reported to district health authorities and consenting to the study; age and hospital matched controls. Main outcome measure Percentage of cases of CALD with attributed source of infection. Methods Analysis of secondary patient samples for monoclonal antibody (MAb) type (and sequence type); questionnaire-based interviews, analysis of standard household water samples for Legionella concentration followed by MAb (and sequence) typing of Legionella pneumophila serogroup 1 (Lp1) isolates; among cases taking of additional water samples to identify the infectious source as appropriate; recruitment of control persons for comparison of exposure history and Legionella in standard household water samples. For each case an appraisal matrix was filled in to attribute any of three source types (external (non-residence) source, residential non-drinking water (RnDW) source (not directly from drinking water outlet), residential drinking water (RDW) as source) using three evidence types (microbiological results, cluster evidence, analytical-comparative evidence (using added information from controls)). Results Inclusion of 111 study cases and 202 controls. Median age of cases was 67 years (range 25–93 years), 74 (67%) were male. Among 65 patients with urine typable for MAb type we found a MAb 3/1-positive strain in all of them. Compared to controls being a case was not associated with a higher Legionella concentration in standard household water samples, however, the presence of a MAb 3/1-positive strain was significantly associated (odds ratio (OR) = 4.9, 95% confidence interval (CI) 1.7 to 11). Thus, a source was attributed by microbiological evidence if it contained a MAb 3/1-positive strain. A source was attributed by cluster evidence if at least two cases were exposed to the same source. Statistically significant general source types were attributed by calculating the population attributable risk (analytical-comparative evidence). We identified an external source in 16 (14%) cases, and RDW as source in 28 (25%). Wearing inadequately disinfected dentures was the only RnDW source significantly associated with cases (OR = 3.2, 95% CI 1.3 to 7.8) and led to an additional 8% of cases with source attribution, for a total of 48% of cases attributed. Conclusion Using the appraisal matrix we attributed almost half of all cases of CALD to an infectious source, predominantly RDW. Risk for LD seems to be conferred primarily by the type of Legionella rather than the amount. Dentures as a new infectious source needs further, in particular, integrated microbiological, molecular and epidemiological confirmation.

The study of work and life of the Swiss-German psychiatrist Ernst Rüdin, honoured up to our time as "father of psychiatric genealogy", lead to different views. Rüdin early in his life became a racial fanatic, and as a propagandist for the purity of the "Germanic people" he constantly demanded preventive coercive measures against the reproduction of the mentally ill and other, in the racist's view, undesirable persons. With this objective in mind he started his psychiatric research. The results of Rüdin's monograph about the genetics of dementia precox do not withstand scientific criticism but confirmed his preexisting opinions. They served however as scientific reasoning for the forced sterilisation by the Nazis, for which Rüdin's comments were obligatory. The next step, to the holocaust of the mentally ill and the undesirable, was not only tacitly agreed with by Rüdin. Max Weber, Karl Jaspers and others realised at an early time the dangers arising from racial hygienics and voiced their warnings in a plain language. The surviving victims are still waiting for compensation.

Recently, researchers and reporters have made a wide range of claims about the distribution, nature, and societal impact of political polarization. Here I offer reasons to believe that even when they are correct and prima facie merely descriptive, many of these claims have the highly negative side effect of increasing political polarization. This is because of the interplay of two factors that have so far been neglected in the work on political polarization, namely that (1) people tend to conform to descriptive norms (i.e., norms capturing [perceptions of] what others commonly do, think, or feel), and that (2) claims about political polarization often convey such norms. Many of these claims thus incline people to behave, cognize, and be affectively disposed in ways that contribute to social division. But there is a silver lining. People’s tendency to conform to descriptive norms also provides the basis for developing new, experimentally testable strategies for counteracting political polarization. I outline three.

It has been argued that implicit biases are operative in philosophy and lead to significant epistemic costs in the field. Philosophers working on this issue have focused mainly on implicit gender and race biases. They have overlooked ideological bias, which targets political orientations. Psychologists have found ideological bias in their field and have argued that it has negative epistemic effects on scientific research. I relate this debate to the field of philosophy and argue that if, as some studies suggest, the same bias also exists in philosophy then it will lead to hitherto unrecognised epistemic hazards in the field. Furthermore, the bias is epistemically different from the more familiar biases in respects that are important for epistemology, ethics, and metaphilosophy.