Constitutive Bi-Modality in Semantic Fields: From Lived Tension to Measured Critical Values

"Have you ever carried something that changed you?" This question, posed in early dialogues about meaning-making, revealed a fundamental tension: semantic systems operate in two irreducible modes—coupling to environment and structuring internally. We demonstrate that this bi-modality is not empirical contingency but ontological necessity: meaning requires both relation to external context (semantic import) and relation to internal coherence (semantic structure). A singular entity cannot generate meaning in isolation.We formalize this insight through Free Energy principles, deriving coupled field dynamics for external (Ψ_ext) and internal (Ψ_int) semantic components. Normal mode analysis yields Ψ⁺ = (Ψ_ext + Ψ_int)/2 (total field activity) and Ψ⁻ = |Ψ_ext - Ψ_int|/2 (intermodal tension). The theory predicts bi-modal distribution in Ψ⁻, orthogonality between environmental coupling (ECI) and internal structuring (ISI), and critical transition values.Across 115 discourse windows and 393 semantic events from large language model conversations, we construct ECI from transfer entropy proxies and ISI from coherence, structural integrity, and discourse linearity metrics. Gaussian mixture models reveal robust bi-modality: ΔBIC ranges from 8 (ECI) to 69 (Ψ⁻* in events), with Silhouette coefficients 0.61-0.69. Two tension regimes emerge at Ψ⁻ ≈ 0.35 and Ψ⁻ ≈ 1.1-1.4, defining critical transition band Ψ⁻_c ≈ 0.8 ± 0.2. ECI and ISI demonstrate near-perfect orthogonality (r = -0.13), validating constitutive independence of coupling modes.These results establish bi-modality as measurable phase structure in semantic fields, with implications for cognitive architectures, AI systems, and the physics of meaning.