A research paper submitted to arXiv on 8 May 2026 proposes a new framework for understanding how post-training methods affect large language models 1. Titled "On Distinguishing Capability Elicitation from Capability Creation in Post-Training: A Free-Energy Perspective," the paper was authored by Yuhao Li and Shengchao Liu 1.

The authors argue that post-training research should distinguish between capability elicitation and capability creation 1. To operationalize this distinction, they introduce the concept of accessible support: the set of behaviors a model can practically produce under finite budgets 1.

Under this framework, post-training that reweights behaviors within this support constitutes capability elicitation, while changing the support itself represents capability creation 1. This distinction addresses what the authors describe as an overly coarse treatment of supervised fine-tuning as imitation and reinforcement learning as discovery 1.

The paper develops its argument through a free-energy view of post-training 1. Both supervised fine-tuning and reinforcement learning can be understood as reweighting a pretrained reference distribution, differing only in their external signals: demonstration signals define low-energy behavior for supervised fine-tuning, while reward signals do so for reinforcement learning 1.

When updates remain close to the base model, the paper argues, the primary effect is local reweighting rather than capability creation 1. Within this framework, the central question shifts from whether post-training is framed as supervised fine-tuning or reinforcement learning to whether it reweights behaviors already within reach or expands the model's reachable behavioral space through search, interaction, tool use, or the incorporation of new information 1.

The paper is categorized under Artificial Intelligence, Statistical Mechanics, and Machine Learning 1. It carries the arXiv identifier arXiv:2605.08368 and has been assigned the DOI 10.48550/arXiv.2605.08368 1. The first version was submitted on 8 May 2026 at 18:23:25 UTC, with a file size of 55 KB 1.

The paper is licensed under Creative Commons BY 4.0 1. Support for arXiv is gratefully acknowledged from the Simons Foundation, member institutions, and all contributors 1.

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