AI's Hidden Smarts: Unlocking Base Models Without Retraining

New research reveals how simple sampling can boost AI reasoning, challenging traditional methods.

A recent paper by Aayush Karan and Yilun Du introduces an iterative sampling algorithm that significantly enhances the reasoning capabilities of large language models (LLMs) without additional training. This method, inspired by Markov chain Monte Carlo techniques, achieves results comparable to or even surpassing those from reinforcement learning (RL) on various tasks. It suggests that base models are inherently smarter than previously thought.

Sarah Kline

By Sarah Kline

October 19, 2025

4 min read

AI's Hidden Smarts: Unlocking Base Models Without Retraining

Key Facts

  • The paper "Reasoning with Sampling: Your Base Model is Smarter Than You Think" was submitted to arXiv on October 16, 2025.
  • The research introduces a simple iterative sampling algorithm for large language models (LLMs).
  • This algorithm enhances reasoning capabilities without requiring additional training, curated datasets, or a verifier.
  • It achieves reasoning boosts that nearly match or even outperform reinforcement learning (RL) on tasks like MATH500, HumanEval, and GPQA.
  • The method prevents the collapse in diversity of samples, a common issue with RL-posttraining.

Why You Care

What if your AI tools could get dramatically smarter without needing costly, time-consuming retraining? This new research from Aayush Karan and Yilun Du shows that it’s possible. They’ve found a way to unlock hidden reasoning abilities in existing large language models (LLMs). This could mean more AI for you, available much faster and cheaper.

Their method suggests that the base models you’re already using possess untapped potential. This could change how we develop and deploy AI, making capabilities more accessible. Imagine getting top-tier performance from your current models, just by using a smarter approach.

What Actually Happened

Aayush Karan and Yilun Du submitted a paper titled “Reasoning with Sampling: Your Base Model is Smarter Than You Think” to arXiv, according to the announcement. This paper details a novel approach to enhancing the reasoning abilities of large language models (LLMs). Traditionally, improving these models often involves extensive post-training with reinforcement learning (RL).

The researchers, however, explored whether comparable reasoning could be achieved from base models at inference time. Inference time refers to when a model is used to make predictions, not during its training phase. They proposed a simple iterative sampling algorithm, inspired by Markov chain Monte Carlo (MCMC) techniques, as detailed in the blog post. This algorithm leverages the base models’ own likelihoods to improve performance.

Why This Matters to You

This new sampling algorithm offers substantial boosts in reasoning across different base models, the research shows. It nearly matches and sometimes even outperforms results from reinforcement learning (RL) on various single-shot tasks. These tasks include challenging benchmarks like MATH500, HumanEval, and GPQA, as mentioned in the release. This means your existing AI could become significantly more capable without needing expensive updates.

For example, imagine you run a small business using an off-the-shelf LLM for customer support. Instead of waiting for a new, more , and expensive model to be released, your current model could suddenly handle more complex queries. This is achieved simply by applying this clever sampling technique. “Our method does not require training, curated datasets, or a verifier,” the paper states. This makes it incredibly flexible and broadly applicable.

What’s more, the sampler avoids a common issue with RL-posttraining: the collapse in diversity over multiple samples. This means your AI will likely generate more varied and creative responses. How might more diverse and accurate AI outputs change your daily workflow or creative projects?

FeatureTraditional RL Post-trainingIterative Sampling Algorithm
Training RequiredYes, extensiveNo
Datasets NeededYes, curatedNo
VerifierOften requiredNo
DiversityCan collapseMaintained
Cost/TimeHighLow

The Surprising Finding

The most surprising aspect of this research is its core premise: “Your Base Model is Smarter Than You Think.” The study finds that comparable reasoning capabilities can be elicited from base models without any additional training. This challenges the common assumption that significant performance gains in LLMs always require resource-intensive fine-tuning or reinforcement learning.

Instead, the team revealed that pure sampling at inference time can unlock these abilities. This is a significant twist because much of the literature focuses on what new behaviors emerge during RL. However, this paper shifts the focus to what capabilities are already present but dormant. The algorithm uses the model’s own likelihoods, effectively guiding it to better solutions. This suggests an inherent intelligence within the base models that was previously overlooked.

What Happens Next

This research opens up exciting possibilities for the future of AI creation. We could see this iterative sampling algorithm integrated into existing LLM deployment pipelines within the next 6-12 months. This would allow developers to enhance model performance without costly retraining cycles. The technical report explains that this method avoids the need for curated datasets or a verifier. This makes it highly adaptable to various domains.

For example, a content creation system currently using an LLM for drafting articles could implement this sampling technique. This would immediately improve the coherence and logical flow of the generated text. This could lead to higher quality outputs for your content. The industry implications are vast, potentially democratizing access to more AI. Companies might not need massive budgets for continuous model updates. They could instead use the latent capabilities of their current models. The authors hope their work suggests “broad applicability beyond easily verifiable domains.”

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