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 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. v14 changelog (June 2026) adds a sustained treatment of where the four fields come from — their derivation and their installation in a substrate. (1) §2.1.1 — the dependency among the fields is recast as constitutive rather than agentic (a higher field is well-defined only given the field beneath it; direction is meaningful only given valence), and a three-level installation account is added (machinery, exposure, and the resulting field), distinguishing what evolution elaborates — the machinery and the order of problems — from what a substrate's own exposure installs. (2) §2.1.1, §3.6, §3.8 — a value/capacity (nurture/nature) decomposition: the value fields (Safety, Meaning) are predominantly exposure-installed, the capacity fields (Ability, Effort) predominantly read off the substrate, framed as a gradient rather than a hard boundary and reconciled with the cross-substrate field-map. (3) §3.4 — a cross-field interference account of why an unsafe substrate underperforms at a capable task, separating generic capacity-competition from a threat-specific tilt. (4) §2.1.1, §3.5b — a refinement of the inverted-U as the universal signature of a capacity meeting a demand (a match) rather than a property of any single field, locating Yerkes-Dodson (arousal), aesthetic preference (processing fluency), and flow (skill) as one match-signature with different demand-sources — offered as an integration of established results, not a new effect. (5) §2.1.1 — a deflationary clarification of what does and does not distinguish biological from artificial substrates (the energy cost of computation, dopaminergic signalling, and the capacity for an unresolvable race are not the boundaries they are often taken to be; the residual functional differences reduce largely to prepared priors and the persistent forward-storage of experience). (6) §3.3 — a withdraw-race reading that places interpersonal boundary-setting alongside reactance and refusal. (7) §1.3 — a reconciliation of the evolutionary argument with the installability of the architecture in a non-evolved substrate (selection is hypothesised to converge on, rather than invent, the four fields). Each substantive addition cleared external dual review before release. Companion papers in the friction-theory series (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 (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); Paper 21 — Mount Stupid in the machine (10.5281/zenodo.20562415); Paper 28 — Dread without a dreader (10.5281/zenodo.20690746).