Necessary Conditions for Primary Interoceptive Sentience in Continuous Substrates: A Falsifiable Programme

This paper asks a narrower, more tractable question than "what is consciousness": which physical substrates, if any, could in principle support primary interoceptive sentience — the most basic capacity of a system to register its own physiological state as good or bad for it? Rather than treating this as a purely philosophical question, we formulate it as a set of necessary physical conditions for continuous neuromorphic substrates (e.g. diffusive and Mott memristor networks), each paired with a falsifiable, measurable test. The programme makes no stronger claim than that: it does not propose a theory of consciousness, and it does not claim that the conditions it identifies are sufficient for sentience — only that they appear necessary, argued a posteriori from the biological case. A substrate that fails any test is not a candidate; one that passes all of them remains a provisional candidate, not a confirmed one. This is the distilled entry point of the P0_Distilled research corpus — the shortest, most self-contained paper in the series. The full research programme (Paper I), its extension to minimal self-agency (Paper II), an external critical assessment (Paper III), and two companion papers (philosophical and technical) are cross-linked via the related-works metadata below. Version 2 (September 2026): corrected incomplete literature citations in the related-work comparison (real author names added where missing; two entries that could not be independently verified were removed, along with the paragraphs describing them); softened an overclaimed originality statement to explicitly note the limited scope of the underlying literature survey.Version 3 (September 2026): corrects a file mix-up in Version 2, which was mistakenly published containing content from an unrelated internal exploration (an experimental reframing using Laudan's philosophy-of-science framework, distinct from this paper's Lakatosian structure). This version restores the correct file; no other content changed relative to the intended Version 2.Version 4 (September 2026): adds, in compact form, the load-bearing results of the two companion papers — a summary of the three-stage argument for Postulate 2 together with the four weaknesses identified in the critical assessment (§6), and the Monte Carlo power-analysis results qualifying the N = 50 sample size for the finite-size scaling criterion (§5); adds the observation that only H7 bears evidentially on Postulate 2 (§1); adds the survey-limitation caveat to the Conclusions; corrects the survey size (five works, not seven), the abandonment-criteria count (five, not four) and two cross-references; adds Zenodo DOIs for all companion papers.Version 5 (September 2026): adds a related-work section on nonequilibrium brain dynamics as a marker of the level of consciousness (Sanz Perl et al. 2021; Gilson et al. 2023; G-Guzmán et al. 2023; Sekizawa et al. 2024; Kringelbach et al. 2024), distinguishing it from the programme's focus on valence; adds a caveat on Griffiths phases to the critical scale-invariance condition; adds a note on the thermodynamic consistency of estimating Ψ(t) with Langevin models in the nonlinear regime; clarifies that Postulate 2 is a restricted variant of dual-aspect monism whose arguments are closest to an a posteriori identity thesis; corrects the statement that the No-Go Theorem is a preprint (it is published in Neuroscience of Consciousness).Version 6 (September 2026): adds related work on substrate-dependent views of consciousness and on the indicator-based approach (Butlin et al. 2023; Seth 2025; Findlay et al. 2024; Wiese 2024); discusses the unfolding and substitution arguments against causal-structure criteria and why the operational demarcation is not their standard target (Doerig et al. 2019; Kleiner & Hoel 2021; O'Reilly-Shah et al. 2026); notes that the structural isomorphism behind Postulate 2 faces the Newman problem (Kleiner 2025); adds two results on nonequilibrium brain dynamics (Lynn et al. 2021; Stikvoort et al. 2025); and places the programme's outcome in the precautionary vocabulary of Birch (2024).