Stibbard-Hawkes and von Rueden propose a process-based definition of egalitarianism, arguing that an egalitarian society should be defined by socio-ecological conditions that secure most individuals’ resource access, status, and autonomy. This framework offered an important alternative to outcome-based equality, which equates egalitarianism with equal distributions of power, wealth, and rank. However, the contrast between process-based and outcome-based egalitarianism corresponds closely to a theoretical distinction between equity and equality (Espinoza, Reference Espinoza2007). Clarifying the conceptual distinction between equity and equality helps further illuminate how process-based and outcome-based egalitarianism reflect different principles governing justice and why both should be considered in the pursuit of justice.

Equity Theory (Adams, Reference Adams1963; Adams & Freedman, Reference Adams and Freedman1976) provides a useful framework for interpreting these principles. It argues that people judge fairness by computing a ratio of their outcomes to inputs and comparing it with others’ ratios. Process-based egalitarianism closely resembles equity-based principles, under which resources are distributed according to individuals’ legitimate needs so that proportionality between inputs and outcomes is maintained and perceptions of fairness are preserved. By contrast, outcome-based egalitarianism parallels equality-based principles, which prescribe identical outcomes for individuals regardless of differences (Deutsch, Reference Deutsch1975; Van Hootegem et al., Reference Van Hootegem, Abts and Meuleman2020). This can be understood as a special case of Equity Theory’s ratio framework in which inputs are assumed to be equal (e.g., normalized to 1 across individuals), thereby eliminating input variation and reducing fairness evaluations primarily to outcome comparisons. Therefore, the equality-based principle evaluates fairness by the extent of sameness, assuming equal outcomes with diverse outcome-input ratios, regardless of the inputs.

In discussions of fairness and justice, equity and equality are two commonly used guidelines for resource allocation. Although the two principles may sometimes produce similar outcomes, particularly when individual differences are negligible, they differ in mechanisms (Siemoneit, Reference Siemoneit2023), and individuals and groups can differ in perceptions and endorsement of these principles. We argue that relying solely on process-based criteria may also obscure persistent intergroup inequalities, even when most individuals appear to be granted comparable levels of resource access, status, and autonomy. Several limitations should be considered when relying solely on a process-based definition of egalitarianism, particularly when applying this framework to modern large-population societies, which we list below.

First, accumulated advantages (e.g., wealth, work experience, and knowledge) can reinforce systematically unequal outcomes even under procedurally fair allocation systems (DiPrete & Eirich, Reference DiPrete and Eirich2006; van Dijk et al., Reference van Dijk, Kooij, Karanika-Murray, De Vos and Meyer2020). Modernization and meritocratic beliefs may weaken redistributive mechanisms, such as demand-sharing, which was introduced in the target paper. As resources become more storable and defensible, and as outcomes are increasingly attributed to individual merit, social pressures to redistribute diminish. Consequently, individuals are able to accumulate and retain resources, allowing even small initial differences to compound over time into persistent intergroup and intergenerational inequalities.

Second, process-based rules may be difficult to enforce or unnecessary in practice in certain contexts. Even when norms prescribe fair procedures, individuals may interpret rules strategically or apply them inconsistently, particularly when assessments of individual needs, contributions, or circumstances remain inherently subjective. For example, in the workplace, highly productive employees may believe they are qualified for more resources as rewards based on their contributions, while junior employees may also view additional resources as justified by their need for training and skill development. As a result, claims about “deserved” resources often reflect subjective construal shaped by self or group interest. Moreover, in many contexts, considerations of efficiency may take precedence over procedural fairness, making outcome-based rules easier to implement. For example, organizations may allocate equal bonuses or standardized benefits across employees to reduce administrative complexity and coordination costs, even when individual contributions differ.

Third, some forms of collective cooperation may require relatively equal outcomes to maintain group cohesion. Individuals may voluntarily adopt outcome-based principles to signal a good reputation of cooperation, even when differentiation is reasonable (Baumard et al., Reference Baumard, André and Sperber2013). When outcome disparities become too large, individuals may perceive the system as unfair and potentially undermining cooperation, even if process-based procedures were closely followed. Cultural norms in some societies prioritize similarity and social cohesion over differentiated allocations. In such contexts, equal outcomes may serve as an important symbolic signal of solidarity (Hoenig et al., Reference Hoenig, Pliskin and De Dreu2024), even when individual differences could justify process-based distributions.

Fourth, only focusing on process-based rules may also obscure inequality and reduce motivation to address them, which resonates with the persistence of gender inequalities in egalitarian societies discussed in the target article. Even if males and females are granted the same autonomy, social norms and cultural constructs often define values and ambitions differently across gender roles, shaping distinct expectations and opportunities for men and women (Cislaghi & Heise, Reference Cislaghi and Heise2020; Eagly & Wood, Reference Eagly and Wood2012). As a result, purely process-based egalitarianism may still result in inequality when social norms structure unequal incentives and roles (Cheryan et al., Reference Cheryan, Ziegler, Montoya and Jiang2017; Iniesto & Bossu, Reference Iniesto and Bossu2023).

The above discussion highlights the limitations of process-based rules. At the same time, evaluating egalitarianism solely through an outcome-based approach may also be insufficient. A focus on equalizing outcomes may overlook legitimate differences in individuals’ training, embodied capital, or social capital, as discussed in the target article. Integrating both perspectives may therefore provide a more comprehensive framework for understanding egalitarian principles. We propose that egalitarianism is a context-dependent construct, such that its meaning and function vary across socio-ecological settings and task domains.

As a context-dependent construct, egalitarianism should be understood in relation to broader socio-ecological conditions. Here, we focus on the degree of social homogeneity and demographic diversity as illustrative dimensions. In contexts characterized by high social homogeneity and low demographic diversity, process-based egalitarianism may approximate outcome-based egalitarianism. Under such conditions, similar needs, constraints, and contributions across individuals result in both allocation procedures producing comparable outcomes. However, this equivalence does not readily generalize to other large-scale societies characterized by substantial demographic and cultural diversity, as well as limited direct interpersonal knowledge among members (Spadaro et al., Reference Spadaro, Graf, Jin, Arai, Inoue, Lieberman, Rinderu, Yuan, Van Lissa and Balliet2022). Therefore, differentiating their appropriate use across contexts is critical, and integrating both perspectives may offer a more comprehensive framework for understanding egalitarian principles in diverse contemporary societies.