In this paper, I pick up on an important theme in Mario Rizzo’s work: that rationality should be understood more broadly than the rational choice model as learning to adjust behaviour in the light of experience and the mistakes that it yields. In particular, I focus on learning-by-doing (LBD). I argue in the first part of the paper that it should be regarded as one of the central insights in economics, alongside those that are more usually recognised like the gains from trade and the importance of unintended consequences. I use Smith and Hirschman’s discussion of LBD to ground this claim. In the second part of the paper, I turn to the determinants of LBD in teams. I argue that the key rule or constitutional/policy design question is how best to embrace the diversity that is central to LBD within teams without this undermining the social origins of co-operation in teams.

Daniel Kahneman's legacy is best understood in light of developments in economic theory in the early-mid-20th century, when economists were eager to put utility functions on a firm mathematical foundation. The axiomatic system that provided this foundation was not originally intended to be normative in a prescriptive sense but later came to be seen that way. Kahneman took the axioms seriously, tested them for descriptive accuracy, and found them wanting. He did not view the axioms as necessarily prescriptive. Nevertheless, in the research program he conceived, factual discoveries about real decision-making were stated as deviations from the axioms and thus deemed ‘errors’. This was an unfortunate turn that needs to be corrected for the psychological enrichment of economics to proceed in a productive direction.

In the philosophy of mind and cognitive science, there is a pronounced paradigm shift associated with the transition from internalism to externalism. The externalist paradigm views cognitive processes as not isolated in the brain, but as interrelated with external artefacts and structures. The paper focuses on one of the leading externalist approaches – extended cognition. Despite the dominance of internalism in economics, in its main schools, there is an emerging trend towards extended cognition ideas. In my opinion, economists might develop the most advanced version of the extended cognition approach: socially extended cognition based on cognitive institutions. This paper analyses extended cognition ideas in institutional, Austrian, and behavioural economics and identifies numerous overlapping approaches and complementary research areas. I argue that the economics of cognitive institutions is a promising field for all economic schools and propose a preliminary research agenda.

The $4 n^2$-inequality for smooth points plays an important role in the proofs of birational (super)rigidity. The main aim of this paper is to generalize such an inequality to terminal singular points of type $cA_1$, and obtain a $2 n^2$-inequality for $cA_1$ points. As applications, we prove birational (super)rigidity of sextic double solids, many other prime Fano 3-fold weighted complete intersections, and del Pezzo fibrations of degree $1$ over $\mathbb {P}^1$ satisfying the $K^2$-condition, all of which have at most terminal $cA_1$ singularities and terminal quotient singularities. These give first examples of birationally (super)rigid Fano 3-folds and del Pezzo fibrations admitting a $cA_1$ point which is not an ordinary double point.

This short article aims to strengthen Hume's case against the rationality of believing in religious miracles by incorporating certain lessons borrowed from the growing literature on the history and psychology of magic tricks.

First, Mahtani argues that both in the game The Mug and in the Sleeping Beauty we should not defer to a trusted person under a particular designation if they do not self-identify under this designation. This invites a more complex Reflection Principle. I respond that there are more parsimonious ways to avoid the challenges posed to the Reflection Principle. Second, Mahtani argues that preferences create a hyperintensional context, which poses a challenge to the Ex-Ante Pareto Principle that can be averted by supervaluation. I respond that such an appeal to supervaluation would block randomization as a fair allocation device.

Must rational thinkers have consistent sets of beliefs? I shall argue that it can be rational for a thinker to believe a set of propositions known to be inconsistent. If this is right, an important test for a theory of rational belief is that it allows for the right kinds of inconsistency. One problem we face in trying to resolve disagreements about putative rational requirements is that parties to the disagreement might be working with different conceptions of the relevant attitudes. My aim is modest. I hope to show that there is at least one important notion of belief such that a thinker might rationally hold a collection of beliefs (so understood) even when the thinker knows their contents entail a contradiction.

Recent work has argued for a Hayekian behavioural economics, which combines Austrian economics with behavioural economics as developed by Kahneman, Thaler, Sunstein, and others. We suggest that this hybrid is misguided because it relies on individual cognitivism. This view of cognition is incompatible with the Hayekian view of cognition which treats rationality as an emergent phenomenon of social interaction in an institutional environment. This Hayekian view, which we call epistemic institutionalism, is compatible with an alternative prominent perspective in psychology, that of the extended mind, sometimes known as 4E cognition. We demonstrate how the Hayekian perspective on individualism, the price system, and the evolution of rules can be connected to the extended mind programme, through concepts such as the coupling of the individual and their environment, cognitive off-loading, and affordances. We suggest that this alternative combination of Austrian economics and psychology provides a more fruitful way forward, especially because it foregrounds the processes of learning, error-correction, and institutional orders, rather than choice, bias, and individual rationality. To explain why Austrian economists have been receptive to behavioural economics, we distinguish epistemic institutionalism from the (radical) subjectivist approach, which shares key assumptions of individual cognitivism.

Questions surrounding deep disagreement have gained significant attention in recent years. One of the central debates is metaphysical, focusing on the features that make a disagreement deep. Proposals for what makes disagreements deep include theories about hinge propositions and first epistemic principles. In this paper, I criticize this metaphysical discussion by arguing that it is methodologically flawed. Deep disagreement is a technical or semi-technical term, but the metaphysical discussion mistakenly treats it as a common-sense concept to be analyzed and captured by our pre-theoretical intuitions. Since the literature on deep disagreement is subject to this fundamental confusion and deep disagreement is not a helpful umbrella term either, I propose eliminating the notion of deep disagreement from the philosophical discourse. Instead of analyzing the nature of deep disagreement, we should develop theories about different forms of disagreement, including disagreement about hinge propositions and disagreement about epistemic principles, and, in particular, a theory of rationally irresolvable disagreement.

Risk is inherent to many, if not all, transformative decisions. The risk of regret, of turning into a person you presently consider to be morally objectionable, or of value change are all risks of choosing to transform. This aspect of transformative decision-making has thus far been ignored, but carries important consequences to those wishing to defend decision theory from the challenge posed by transformative decision-making. I contend that a problem lies in a common method used to cardinalise utilities – the von Neumann and Morgenstern (vNM) method – which measures an agent's utility function over sure outcomes. I argue that the risks involved in transformative experiences are constitutively valuable, and hence their value cannot be accurately measured by the vNM method. In Section 1, I outline what transformative experiences are and the problem they pose to decision theory. In Section 2, I outline Pettigrew's (2019, Choosing for Changing Selves) decision-theoretic response, and in Section 3, I present the case for thinking that risks can carry value. In Section 4, I argue for the claim that at least some transformative experiences involve constitutive risk. I argue that this causes a problem for decision-theoretic responses within the vNM framework in Section 5.