Persona Without Substrate: Regime-Dependence and the LLM Individuation Problem

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[Submitted on 1 May 2026]

Title:Persona Without Substrate: Regime-Dependence and the LLM Individuation Problem

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Abstract:Beckmann & Butlin's (2026) ontological framework for the LLM individuation problem inherits an unargued cross-regime co-reference assumption from the persona-vectors literature: that the same direction picks out the same content under prompt-conditioning, gradient-descent fine-tuning, and inference-time steering. We present four empirical wedges from persona-topology experiments on Qwen3-4B-Instruct and Mistral-7B-Instruct-v0.2 - non-collinearity of prompt-extracted vectors and fine-tune basins; fictional personas displacing the model along real-anchor directions more strongly than real anchors do; contradictory-valenced mixtures biased toward a training-history-determined attractor; and asymmetric compositional algebra under inference-time arithmetic versus fine-tune-time chimera training - that jointly undermine the assumption. We propose regime-indexed individuation: the identity unit for representational content is a (vehicle, regime) pair, not a vehicle alone. Under this framework, Beckmann & Butlin's three candidate positions describe three different regime-internal objects rather than competing for the same referent; the same diagnosis applies to Mollo & Millière, Chalmers, and Cerullo.

Comments: 30 pages, 2 figures, 1 table. Replies to Beckmann & Butlin (arXiv:2604.17031)

Subjects:

Computation and Language (cs.CL); Artificial Intelligence (cs.AI)

Cite as: arXiv:2607.00006 [cs.CL]

(or arXiv:2607.00006v1 [cs.CL] for this version)

https://doi.org/10.48550/arXiv.2607.00006

arXiv-issued DOI via DataCite

Submission history

From: Shuaizhi Cheng [view email] [v1] Fri, 1 May 2026 12:33:05 UTC (73 KB)

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