Quantifying Harm

TL;DR

This paper develops a framework for quantifying harm in decision-making, addressing individual and societal levels, and discusses implications for precision medicine and decision theory.

Contribution

It introduces a formal quantitative definition of harm, explores issues in aggregating harm across individuals, and critiques common aggregation methods.

Findings

Expected harm aggregation can lead to counterintuitive results.

Alternative aggregation methods are discussed based on decision theory.

The framework is applied to debates in precision medicine.

Abstract

In earlier work we defined a qualitative notion of harm: either harm is caused, or it is not. For practical applications, we often need to quantify harm; for example, we may want to choose the least harmful of a set of possible interventions. In this work, which is an expanded version of an earlier conference paper, we develop a quantitative notion of harm. We first present a quantitative definition of harm in a deterministic context involving a single individual, then we consider the issues involved in dealing with uncertainty regarding the context and going from a notion of harm for a single individual to a notion of "societal harm", which involves aggregating the harm to individuals. We show that the "obvious" way of doing this (just taking the expected harm for an individual and then summing the expected harm over all individuals) can lead to counterintuitive or inappropriate answers, and discuss alternatives, drawing on work from the decision-theory literature. Finally, we connect our work to a recent debate over harm within the context of precision medicine.