The Method of Reflective Equilibrium

Reflective Equilibrium (RE) is a method of justification to which many philosophers appeal.

The basic idea of RE is the mutual adjustment of commitments and theory to each other: An agent starts with what she is committed to accept about a certain topic. Theories are supposed to systematize her commitments. The agent goes back and forth between the commitments and theory, and tries to adjust them to each other until an equilibration state is reached.

Since RE was so far underspecified, we have recently developed a more precise account (Baumberger and Brun 2016; 👉 details) and a formal model of RE (Beisbart, Betz and Brun 2021; 👉 details). It uses some minimal logic and can be solved using computer simulations.

This subproject evaluated the plausibility of RE as a method of justification. Are the theoretical virtues implicit in RE plausible? And how can we strike a reasonable balance between them?

Using the formal model of reflective equilibrium, Richard Lohse studied in how far individuals can justifiedly agree on modes of collective decision-making whilst holding fundamentally different worldviews. The target state is what political philosopher John Rawls called an overlapping consensus: Even though citizens hold a pluralism of comprehensive moral doctrines, they nonetheless agree on a shared political conception of justice. But this agreement is not a mere compromise. Instead, each citizen believes in both their comprehensive moral doctrine and the shared political conception of justice for moral reasons: Their moral belief system as a whole is in reflective equilibrium. Richard Lohse conducted simulation studies in order to identify conditions under which an overlapping consensus is possible or even likely.