Carlo Martini

Is subjective expert judgment a source of evidence in economics? In this paper, I will argue that it is, on a par with other sources like modeling, statistics, experimental, etc. I will also argue that it is not derivative, that is, reducible to the previous ones. But what is exactly the role of experts in economics? The contribution to the current methodological debate that I propose not only takes the role of expertise in economics as indispensable, but also suggests a need for a methodology associated with that role. I defend an indispensability argument, and indirectly David Colander's plea for refocusing the methodological debate on the lost art of economics. Finally, I indicate where to look for guidelines in formulating a methodology of economic expertise.

This paper applies the theory of networks to the problem of how agents should assign weights to other agents in the Lehrer-Wagner model for consensus formation. The Lehrer- Wagner theory of consensus is introduced, and the problem of weight assignment is highlighted as one of the open prob- lems for the theory. The paper argues that the application of the theory of networks to the Lehrer-Wagner model con- stitutes an interesting and fruitful option, among others, for the problem of weight assignment

This paper explores the scope and limits of rational consensus through mutual respect, with the primary focus on the best known formal model of consensus: the Lehrer–Wagner model. We consider various arguments against the rationality of the Lehrer–Wagner model as a model of consensus about factual matters. We conclude that models such as this face problems in achieving rational consensus on disagreements about unknown factual matters, but that they hold considerable promise as models of how to rationally resolve non-factual disagreements.

The claim that diversity and independence have a net positive epistemic effect on the judgments of groups has been recently defended formally by Scott Page, among others, and popularized in Surowiecki's The Wisdom of Crowds. In Meta-Induction and the Wisdom of Crowds Thorn and Schurz take issue with the claim that more diversity and independence in groups leads to better collective judgments. I argue that Thorn and Schurz's arguments are helpful in clarifying a number of over-generalizations about diversity and independence that are often circulated in the social epistemology literature. I also argue that the relevant formal arguments are easily misunderstood when presented 'in a vacuum', that is, without a context of application in mind. I provide a different approach to understanding formal results in social epistemology: With the help of concrete scenarios and the formal literature, I focus on a trade-off between independence and dependence in groups. I show that the approach works well also for another principle in social epistemology; namely, the principle that 'more heads are better than few'.

In this paper we argue that there is a kind of moral disagreement that survives the Rawlsian veil of ignorance. While a veil of ignorance eliminates sources of disagreement stemming from self-interest, it does not do anything to eliminate deeper sources of disagreement. These disagreements not only persist, but transform their structure once behind the veil of ignorance. We consider formal frameworks for exploring these differences in structure between interested and disinterested disagreement, and argue that consensus models offer us a solution concept for disagreements behind the veil of ignorance.

In this paper I analyze four so-called “principles of expertise”; that is, good epistemic practices that are normatively motivated by the epistemological literature on expert judgment. I highlight some of the problems that the four principles of expertise run into, when we try to implement them in concrete contexts of application (e.g. in science committees). I suggest some possible alternatives and adjustments to the principles, arguing in general that the epistemology of expertise should be informed both by case studies and by the literature on the use of experts in science practice