Proportionality in cyberwar and just war theory

Which harms and benefits should be viewed as relevant when considering whether to launch cyber-measures? In this article, we consider this question, which matters because it is central to determining whether cyber-measures should be launched. Several just war theorists hold a version of what we call the 'Restrictive View', according to which there are restrictions on the sorts of harms and benefits that should be included in proportionality assessments about the justifiability of going to war (whether cyber or kinetic). We discuss two such views - the Just Cause Restrictive View and Rights-based Restrictive View - and find both wanting. By contrast, we defend what we call the 'Permissive View'. This holds that all potential goods and bads should be included in proportionality decisions about cyber-measures, even those that appear to be trivial, and where the various harms and benefits are given different weights, according to their agent-relative and agent-neutral features. We argue further that accepting the Permissive View has broader implications for the ethical frameworks governing cyberwar, both in terms of whether cyberattack provide just cause for coercive responses, including kinetic warfare and cyber-responses, and whether cyber-measures should be governed by just war theory or a new theory for cyber-operations.