Structural Analogy and Structural Equivalence: A Constraint-Based Criterion for Intertradition Comparison

Comparative inquiry across religious and philosophical traditions faces a persistent methodological problem: how to distinguish structural correspondence from surface resemblance. Existing approaches — doctrinal, phenomenological, and historical — lack a formal criterion capable of determining whether similarities between traditions are structurally significant or merely descriptive. This paper proposes a constraint-based framework for addressing this problem. It introduces a formally defined distinction between structural analogy and structural equivalence, grounded in a dependency-ordered constraint profile governing the integration of ontological, historical, and normative registers. Two procedures operationalize this framework: the Test of Differential Pressure (TPD), which locates divergence within the constraint topology, and the Criterion of Structural Ineliminability (CIE), which determines whether such divergence can be resolved by internally admissible reinterpretation or is structurally fixed. The central result is that the transition from structural analogy to structural equivalence is not gradual but topological: equivalence requires invariance under the full configuration of constraints and their dependency relations, a condition that does not admit scalar approximation. The contribution is methodological. The paper provides a formal criterion with explicit decision conditions for evaluating structural relations across traditions, without presupposing doctrinal commitments or adjudicating theological truth.