The problem of evaluating automated large-scale evidence aggregators

In the biomedical context, policy makers face a large amount of potentially discordant evidence from different sources. This prompts the question of how this evidence should be aggregated in the interests of best-informed policy recommendations. The starting point of our discussion is Hunter and Williams’ recent work on an automated aggregation method for medical evidence. Our negative claim is that it is far from clear what the relevant criteria for evaluating an evidence aggregator of this sort are. What is the appropriate balance between explicitly coded algorithms and implicit reasoning involved, for instance, in the packaging of input evidence? In short: What is the optimal degree of ‘automation’? On the positive side: We propose the ability to perform an adequate robustness analysis as the focal criterion, primarily because it directs efforts to what is most important, namely, the structure of the algorithm and the appropriate extent of automation. Moreover, where there are resource constraints on the aggregation process, one must also consider what balance between volume of evidence and accuracy in the treatment of individual evidence best facilitates inference. There is no prerogative to aggregate the total evidence available if this would in fact reduce overall accuracy

Challenging the Majority Rule in Matters of Truth

The majority rule has caught much attention in recent debate about the aggregation of judgments. But its role in finding the truth is limited. A majority of expert judgments is not necessarily authoritative, even if all experts are equally competent, if they make their judgments independently of each other, and if all the judgments are based on the same source of (good) evidence. In this paper I demonstrate this limitation by presenting a simple counterexample and a related general result. I pave the way for this argument by introducing a Bayesian model of evidence and expert judgment in order to give a precise account of the basic problem

A Logic for Reasoning about Group Norms

We present a number of modal logics to reason about group norms. As a preliminary step, we discuss the ontological status of the group to which the norms are applied, by adapting the classification made by Christian List of collective attitudes into aggregated, common, and corporate attitudes. Accordingly, we shall introduce modality to capture aggregated, common, and corporate group norms. We investigate then the principles for reasoning about those types of modalities. Finally, we discuss the relationship between group norms and types of collective responsibility

On the Possibility of Democracy and Rational Collective Choice

The paper challenges the 'orthodox doctrine' of collective choice theory according to which Arrow’s 'general possibility theorem' precludes rational decision procedures generally and implies that in particular all voting procedures must be flawed. I point out that all voting procedures are cardinal and that Arrow’s result, based on preference orderings cannot apply to them. All voting procedures that have been proposed, with the exception of approval voting, involve restrictions on voters expressions of their preferences. These restrictions, not any general impossibility, are the cause of various well known pathologies. In the class of unrestricted voting procedures I favor 'evaluative voting' under which a voter can vote for or against any alternative, or abstain. I give a historical/conceptual analysis of the origins of theorists’ aversion to cardinal analysis in collective choice and voting theories

A non-proposition-wise variant of majority voting for aggregating judgments

Majority voting is commonly used in aggregating judgments. The literature to date on judgment aggregation (JA) has focused primarily on proposition-wise majority voting (PMV). Given a set of issues on which a group is trying to make collective judgments, PMV aggregates individual judgments issue by issue, and satisfies a salient property of JA rules—independence. This paper introduces a variant of majority voting called holistic majority voting (HMV). This new variant also meets the condition of independence. However, instead of aggregating judgments issue by issue, it aggregates individual judgments en bloc. A salient and straightforward feature of HMV is that it guarantees the logical consistency of the propositions expressing collective judgments, provided that the individual points of view are consistent. This feature contrasts with the known inability of PMV to guarantee the consistency of the collective outcome. Analogously, while PMV may present a set of judgments that have been rejected by everyone in the group as collectively accepted, the collective judgments returned by HMV have been accepted by a majority of individuals in the group and, therefore, rejected by a minority of them at most. In addition, HMV satisfies a large set of appealing properties, as PMV also does. However, HMV may not return any complete proposition expressing the judgments of the group on all the issues at stake, even in cases where PMV does. Moreover, demanding completeness from HMV leads to impossibility results similar to the known impossibilities on PMV and on proposition-wise JA rules in genera

Judgment aggregation in search for the truth

We analyze the problem of aggregating judgments over multiple issues from the perspective of whether aggregate judgments manage to efficiently use all voters' private information. While new in judgment aggregation theory, this perspective is familiar in a different body of literature about voting between two alternatives where voters' disagreements stem from conflicts of information rather than of interest. Combining the two bodies of literature, we consider a simple judgment aggregation problem and model the private information underlying voters' judgments. Assuming that voters share a preference for true collective judgments, we analyze the resulting strategic incentives and determine which voting rules efficiently use all private information. We find that in certain, but not all cases a quota rule should be used, which decides on each issue according to whether the proportion of ‘yes’ votes exceeds a particular quota

Security for Expense Statutes: Easing Shareholder Hopelessness?

The quintessential derivative suit is a suit by a shareholder to force the corporation to sue a manager for fraud, which is admittedly an awkward and likely unpleasant endeavor and, according to the Supreme Court, a “remedy born of stockholder helplessness.” Where ownership and control of an enterprise are vested in the same population, the need for a corrective mechanism like a derivative suit is greatly lessened because the owner/managers’ self-interests will arguably guide managerial conduct. But where ownership and control are in separate hands, the incentives change, and managerial conduct may not conform to the owners’ views of the best course of action. This may lead to what the owners consider to be director misconduct. The existing corporate laws have not been effective in stopping this kind of director misconduct, so “stockholders, in face of gravest abuses, were singularly impotent in obtaining redress of abuses of trust.” In these situations, shareholders are arguably in need of legal strategies to protect themselves from abuses by management. Presumably in an effort to limit the abuse of strike suits that would take up managerial time, resources, and corporate dollars, several significant procedural hurdles for derivative plaintiffs have arisen, including the requirement of contemporaneous share ownership—a requirement that derivative plaintiffs make a “demand” on the corporation, in particular, to take requested action—the lack of access to the discovery process, and compliance with any relevant security for expense statutes. Balancing the right of shareholders to hold their directors accountable against the need for directors to have the freedom and autonomy to discharge their statutory and fiduciary duties is no easy feat. That said, these hurdles, when combined, may erode or even undermine the ultimate utility of the derivative litigation process

Illusory correlation, group size and memory

Two studies were conducted to test the predictions of a multi-component model of distinctiveness-based illusory correlation (IC) regarding the use of episodic and evaluative information in the production of the phenomenon. Extending on the standard paradigm, participants were presented with 4 groups decreasing in size, but all exhibiting the same ratio of positive to negative behaviours. Study 1 (N = 75) specifically tested the role of group size and distinctiveness, by including a zero-frequency cell in the design. Consistent with predictions drawn from the proposed model, with decreasing group size, the magnitude of the IC effect showed a linear in- crease in judgments thought to be based on evaluative information. In Study 2 (N = 43), a number of changes were introduced to a group assignment task (double presentation, inclusion of decoys) that allowed a more rig- orous test of the predicted item-specific memory effects. In addition, a new multilevel, mixed logistic regression approach to signal-detection type analysis was used, providing a more flexible and reliable analysis than previ- ously. Again, with decreasing group size, IC effects showed the predicted monotonic increase on the measures (group assignment frequencies, likability ratings) thought to be dependent on evaluative information. At the same time, measures thought to be based on episodic information (free recall and group assignment accuracy) partly revealed the predicted enhanced episodic memory for smaller groups and negative items, while also supporting a distinctiveness-based approach. Additional analysis revealed that the pattern of results for judg- ments though to be based on evaluative information was independent of interpersonal variation in behavioral memory, as predicted by the multi-component model, and in contrast to predictions of the competing models. The results are discussed in terms of the implications of the findings for the proposed mechanisms of illusory correlation