Moral Phase Transitions in Collective Social Systems

Standard metaethical theory models moral agency on the individual deliberator, treating groups as mere aggregates. This paper argues that the dynamics of collective moral change undermine both the reducibility thesis and the associated picture of smooth rational updating. Drawing on the concept of bistability in physical systems--wherein stable equilibria are separated by energy barriers and transitions are threshold-crossing rather than gradual--I develop an account of group-level normative states as occupying attractor configurations within a social-normative landscape whose dimensions include institutional enforcement, public legitimacy, coordination incentives, and accountability structures. A minimal formal model of this landscape is developed to show that the bistable structure is not merely metaphorical. I then argue that group normative states are weakly emergent in a technically precise sense: they are constituted by but not computationally derivable from individual-level facts without tracing the full causal history of the system. This emergence claim is connected to an established social-science literature on threshold dynamics and preference falsification. A sustained case study of the abolition of the Atlantic slave trade, with briefer comparisons to women's suffrage and the normalisation of same-sex marriage, illustrates the framework across multiple historical registers. The framework yields three principal metaethical upshots: collective rationality is better characterised by configurational stability and sensitivity to bifurcation conditions than by coherence; group-level normative reasons are structurally irreducible; and collective moral objectivity is grounded in the attractor topology of social systems, its authority deriving from the constitutive relationship between group identity and the normative configurations a group can coherently occupy.