In this paper I investigate the possibility of a dictatorship in the context of Harsanyi's Social Aggregation Theorem. Preliminarily, some propositions about Harsanyi's Theorem are presented using an alternative principle that I name Quasi-strong Pareto, which is the latter part of Strong Pareto. Then I define dictatorship as a requirement that social preference agrees with a dictator's preference or those of members of dictatorial group even if their preferences strictly contradict those of all other people in the society. Conclusively, although (...) in each version of Harsanyi's Theorem with Pareto Indifference, Weak Preference Pareto or Weak Pareto the social utility function may have a form of dictatorship, however if individuals' vNM utility functions are all 'individualistic' and Quasi-strong Pareto is satisfied, then the dictatorship is excluded. (shrink)

Harsanyi defends utilitarianism by means of an axiomatic proof and by what he calls the 'equiprobability model'. Both justifications of utilitarianism aim to show that utilitarian ethics can be derived from Bayesian rationality and some weak moral constraints on the reasoning of rational agents. I argue that, from the perspective of Bayesian agents, one of these constraints, the impersonality constraint, is not weak at all if its meaning is made precise, and that generally, it even contradicts individual rational agency. Without (...) the impersonality constraint, Harsanyi's two justifications of utilitarianism on the grounds of Bayesian rationality fail. As an alternative, I develop a contractarian framework that is compatible with individual rational agency and Harsanyi's central assumptions, and that allows the derivation of moral conclusions on the grounds of Bayesian rationality. The developed framework offers a novel justification of contractarian ethics and may best be described as a combined version of Harsanyi's equiprobability model and Rawls's original position. (shrink)

Effective altruism (EA) requires that when we donate to charity, we maximize the beneficial impact of our donations. While we are in broad sympathy with EA, we raise a practical problem for EA, which is that there is a crucial empirical presupposition implicit in its charity assessment methods which is false in many contexts. This is the presupposition that the magnitude of the benefits (or harms) generated by some charity vary continuously in the scale of the intervention performed. We characterize (...) a wide class of cases where this assumption fails, and then draw out the normative implications of this fact. (shrink)

How should an impartial social observer judge distributions of well-being across different individuals when there is uncertainty regarding the state of the world? I explore this question by imposing very weak conditions of rationality and benevolent sympathy on impartial betterness judgments under uncertainty. Although weak enough to be consistent with all the main theories of rationality, these conditions prove to be sufficient to rule out any heterogeneity in what is good for individuals, to require a neutral attitude to uncertainty on (...) the part of the social observer, and to require that both individual and social betterness be strongly separable. (shrink)

We present an abstract social aggregation theorem. Society, and each individual, has a preorder that may be interpreted as expressing values or beliefs. The preorders are allowed to violate both completeness and continuity, and the population is allowed to be infinite. The preorders are only assumed to be represented by functions with values in partially ordered vector spaces, and whose product has convex range. This includes all preorders that satisfy strong independence. Any Pareto indifferent social preorder is then shown to (...) be represented by a linear transformation of the representations of the individual preorders. Further Pareto conditions on the social preorder correspond to positivity conditions on the transformation. When all the Pareto conditions hold and the population is finite, the social preorder is represented by a sum of individual preorder representations. We provide two applications. The first yields an extremely general version of Harsanyi's social aggregation theorem. The second generalizes a classic result about linear opinion pooling. (shrink)