Title: Native Reasoning Models: Training Language Models to Reason on Unverifiable Data
Primary area: foundation or frontier models, including LLMs
Keywords: LLM, Reinforcement Learning

Abstract: The dominant paradigm for training large reasoning models—combining Supervised Fine-Tuning (SFT) with Reinforcement Learning with Verifiable Rewards (RLVR)—is fundamentally constrained by its reliance on high-quality, human-annotated reasoning data and external verifiers.
This dependency incurs significant data-collection costs, risks embedding human cognitive biases, and confines the reinforcement learning stage to objectively assessable domains like mathematics and coding, leaving a vast landscape of unverifiable tasks unaddressed.
To overcome these limitations, we introduce Native Reasoning Training (NRT), a novel framework that cultivates complex reasoning by having the model generate its own reasoning traces using only standard question-answer pairs, thereby obviating the need for expert-written demonstrations.
NRT reframes the training problem by treating the reasoning process as a latent variable. 
It employs a unified training objective that models reasoning as an optimization problem, intrinsically rewarding paths that increase the model's likelihood of producing the ground-truth answer.
This unified perspective allows us to analyze intrinsic failure modes of prior methods, such as policy collapse, and systematically design more robust reward aggregation functions, creating a self-correcting feedback loop where the model learns to \textit{think} in ways that resolve its own uncertainty.
Empirical evaluation on Llama-3.1-8B and Llama-3.2-3B models demonstrates that NRT achieves state-of-the-art performance among verifier-free methods, significantly outperforming standard SFT baselines and prior verifier-free RL methods.
Our approach yields particularly strong performance gains in complex reasoning domains and exhibits high robustness to policy collapse, offering a general, scalable path toward building more powerful and broadly applicable reasoning systems.

TL;DR: Native Reasoning Training (NRT) cultivates reasoning in base LLMs using only Q&A pairs. It rewards self-generated logic for correct answers, achieving SOTA results for verifier-free methods without needing costly, human-written reasoning examples.