Envy-free is fair enough

Envy-free is fair enough. Purpose: The aim of this chapter is to review the role of envy-freeness (EF) as a core principle of fairness in the allocation of both divisible and indivisible goods, and to evaluate its theoretical robustness, practical relevance, and applicability to real-world allocation problems. Design/methodology/approach: The chapter builds on interdisciplinary literature from economics, computer science, and behavioural studies. It discusses EF and its relaxations (EF1, EFX), alongside other fairness criteria such as Pareto optimality, proportionality, and equitability. The discussion is grounded in theoretical models and supplemented with practical applications including project assignments and school redistricting. Findings: Envy-freeness emerges as a psychologically plausible and socially robust fairness criterion. While strict EF is often unattainable in real-life scenarios involving indivisible items, its relaxations (EF1, EFX) offer operationally feasible alternatives that still ensure high levels of perceived fairness. Simple algorithms such as round-robin and envy-cycle elimination provide transparent procedures for computing such allocations. Applications in education and organisational settings demonstrate EF’s contribution to social welfare, trust, and procedural legitimacy. Originality and value: The chapter contributes to the ongoing debate on fairness in resource allocation by showing that EF and its relaxations balance efficiency with individual satisfaction. By incorporating insights from behavioural economics and algorithmic design, it advocates for fair division mechanisms that are both rigorous and practical, thus enhancing the stability and acceptability of allocation outcomes in complex social systems.