Bayes factors – evidence for one model versus another – are a useful tool in the social and behavioral sciences, partly because they can provide evidence for no effect relative to the sort of effect expected. By contrast, a non-significant result does not provide evidence for the null hypothesis tested. If non-significance does not in itself count against any theory predicting an effect, how could a theory fail a test? Bayes factors provide a measure of evidence from first principles. A severe test is one that is likely to obtain evidence against a theory if it were false – to obtain an extreme Bayes factor against the theory. Bayes factors show why cherry picking degrades evidence, how to deal with multiple testing, and how optional stopping is consistent with severe testing. Further, informed Bayes factors can be used to link theory tightly to how that theory is tested, so that the measured evidence does relate to the theory.

Delusions are false and incorrigible beliefs. They have yet to yield to psychological or neurobiological explanation. Contemporary theories attempt to bridge these levels of explanation. However, they differ in the allowable directions of influence between brain regions and psychological processes. More recently, beliefs and belief updating have fallen under the lens of social network theories. Uniting individual level accounts with those that incorporate the influence of others on ones’ beliefs may yield new avenues for treatment, that leverage key nodes in an individual’s extant social network, or that reconfigure networks to facilitate more healthful and appropriate belief formation and updating.

Chapter 6 focuses on labor market developments and preferences for unemployment policies. Using data from Germany, we show that increasingly, labor market risks can be predicted with a small set of observables (education, occupation, and location), while the relevance of private information has declined over time. Polarization over unemployment policies has risen at the same time. We also explore – theoretically and empirically – how people translate their labor market situation into political preferences and show the importance of social networks in the process. Lastly, the chapter describes a case study of a fascinating reform in the Swedish unemployment insurance system, which shows what happens when unemployment insurance contributions and benefits are tied to unemployment risk, as would happen in a private market. Thus, the Swedish case provides a window into the (possible) future of segmented social policy programs that we predict will become more commonplace.

The wedding of Francesco de’Medici and Giovanna of Austria was accompanied by processions and art that celebrated Florence’s history and its cultural and artistic achievements. Vincenzio Borghini and Giorgio Vasari worked with Duke Cosimo on the program. New paintings on Florentine history in the Palazzo Vecchio led Girolamo Mei to write a treatisethat challenged Borghini’s assessment of the city’s history, using evidence that included the writings of Annius of Viterbo. They exchanged letters that raised issues about the use of ruins and other non-textual evidence. Borghini went on to write Discorsi on Florence’s history and traditions that also explored methods of studying the past; he wrote on medieval coinage, on families and family crests, the nature of nobility, and more. Borghini argued that traditions and social practices develop and change like languages. Many typically Florentine customs, he suggested, developed in parallel with the formation of the city’s government in the thirteenth century.