Partial Aggregation: Foundations, Concepts, and Mechanisms

Room – Roscoe 3.5

Many believe that we ought to save many people from full-body paralysis rather than save a single life, but that it would be wrong to prevent countless headaches rather than saving a single person’s life. Those judgments are in tension. The first favours an aggregative moral ideal, according to which burdens can be added up in moral reasoning, so that they together outweigh a more severe burden. The second favours an anti-aggregative moral ideal, on which sufficiently large burdens retain priority over any number of smaller burdens. Theories of partial (or limited) aggregation aspire to reconcile these judgements in a principled way. Their broader interest lies in the prospect of settling long-standing debates in ethical theory, for example between contractualists and consequentialists, regarding when and why the numbers should count.

While early work in partial aggregation arrived at conclusions regarding whom to save by forming and breaking ties among individuals’ claims to be saved (Kamm 1993, Scanlon 1998), recent theories have developed restrictions on how different kinds of claims can inform such conclusions, depending on their relevance to each other and to the decision at hand (Voorhoeve 2014, Tadros 2019, van Gils & Tomlin 2020, Rüger 2020, Steuwer 2021, Hart 2022, Mann 2022, Zhang 2024). The literature has just begun to explore the range of cases that a theory of partial aggregation would need to address, for example those involving heterogeneous groups (Tomlin 2017, Horton 2018, Tadros 2019, van Gils & Tomlin 2020), multiple options (Mann 2022), non-fixed populations (Harney & Khawaja 2023), quasi-competition (Tomlin 2017, Mann 2021), and risk (Horton 2017 & 2020, Lazar 2018, Walen 2020, Francis 2024). Meanwhile, it remains an open question whether partial aggregation is compatible with individualist moral theories like contractualism (Scanlon 1998, Zhang 2024), or whether instead such theories lead to skepticism about moral aggregation of any kind (Taurek 1977, Otsuka 2000, Munoz-Dardé 2005, Muñoz 2024). Indeed, some have suggested that the difficulties attached to partial aggregation motivate full-blown moral aggregation, with practically no restrictions at all (Parfit 2011, Halstead 2016, Horton 2018).

The proliferation of recent work on partial aggregation suggests a number of pressing open questions, including the following:

• Is partial aggregation consistent or does it collapse into either Full Aggregation or skepticism about aggregation?
• Can partial aggregation be reconciled with individualist moral theory? What makes a moral theory “individualist” in the relevant sense? What is the best formulation of the so-called “individualist restriction”?
• What are moral claims, and how do they relate to reasons? What does it take for claims to be relevant to each other or to one’s decision? How should claims be balanced, added up, cancelled, or otherwise combined?
• What do we expect from a theory of partial aggregation? How should we assess a theory’s extensional adequacy and its explanatory power?
• Do moral and political philosophy call for distinct theories of partial aggregation, or will a unified account suffice? How does partial aggregation bear on public policy?

The panel provides a forum to discuss all of the above and further matters on partial aggregation more generally.