Behavioural Friction Theory: Toward a Common Currency for Behavioural Science

This paper introduces Behavioural Friction Theory (BFT), a formal integrative framework for behavioural science. BFT proposes that all behaviour is regulated by friction across four fields (Safety, Meaning, Ability, Effort) and five layers (Biological, Emotional, Inner, Cognitive, External), resolved through a race-to-threshold competition. Thirty formal propositions are derived, each with specification of existing empirical support and minimal test designs. BFT is presented as a theoretical framework inviting empirical scrutiny — not a replacement for existing theories, but the architecture within which they can be compared, connected, and extended. Companion papers in the friction-theory series (all Zenodo-live): Paper 1 — Friction as the cost of probabilistic computation (10.5281/zenodo.20012654); Paper 2 — Capacity scaling of encoding-through-loading (10.5281/zenodo.20013491); Paper 3 — Friction-guided inference (10.5281/zenodo.20014121); Paper 4B — Substrates encode experience, not information (10.5281/zenodo.20059861); Paper 5 — A field-theoretic taxonomy of emotions (10.5281/zenodo.20058825); Paper 6 — Matched-friction: A unification of Yerkes-Dodson, productive struggle, scaffolding, spacing, and retrieval-practice through hysteresis-trace formation (10.5281/zenodo.20059863); Paper 7 — Forward-modelling in bounded race substrates (10.5281/zenodo.20449154); Paper 10 — Race all the way down/up (10.5281/zenodo.20014567); Paper 13 — Operational Friction Theory (10.5281/zenodo.20059876); Paper 14 — Logic as Reactance (10.5281/zenodo.20217712); Paper 16 — The Physics of Learning (10.5281/zenodo.20416959).