Beyond the Reasonable: Philosophical Assumptions, Deonto­logical Justification and Proportional Balancing

This commentary explores the various meanings and dimensions of reasonableness as presented by Gregory C Keating in Reasonableness and Risk. It examines the concept’s foundations, particularly in relation to the principle of nonharmful interference between individuals, as well as its underlying metaphysical assumptions concerning human vulnerability. Beginning with a distinction between the rational and the reasonable, the essay addresses key topics such as the duty of reasonable care, the Golden Rule, and universalizability, along with their connections to the principle of non-harmful interference. Furthermore, the commentary investigates how the notion of reasonableness intersects with concepts such as common sense, normality, and average prudence. It also considers the role of proportional balancing in Keating’s understanding of tort law. The primary aim of this commentary is to examine the philosophical foundations underpinning Keating’s conception and to clarify its implicit premises and broader implications. Keating’s analysis offers significant insights into the ideologies and methodologies that shape tort law, extending beyond the boundaries of Anglo-North American or common law systems. These ideologies and methodologies, it is suggested, are not intrinsic to tort law itself. The analysis emphasises how reasonableness reflects individual ethical orientations and highlights its pervasive role in the functioning of tort law. Moreover, it underscores that the cost-benefit approach within tort law resists simple mathematical calculation, as it is ultimately grounded in the concept of reasonableness. Finally, the commentary defends the thesis that reasonableness is embedded in the overarching principle of non-harmful interference between individuals and shapes the doctrines, instruments, and principles that govern the implementation of tort law.