Chain-of-Thought Reasoning Without Prompting
Xuezhi Wang Denny Zhou
In enhancing the reasoning capabilities of large language models (LLMs),
prior research primarily focuses on specific prompting techniques such as
few-shot or zero-shot chain-of-thought (CoT) prompting. These methods, while
effective, often involve manually intensive prompt engineering. Our study takes
a novel approach by asking: Can LLMs reason effectively without prompting? Our
findings reveal that, intriguingly, CoT reasoning paths can be elicited from
pre-trained LLMs by simply altering the \textit{decoding} process. Rather than
conventional greedy decoding, we investigate the top-$k$ alternative tokens,
uncovering that CoT paths are frequently inherent in these sequences. This
approach not only bypasses the confounders of prompting but also allows us to
assess the LLMs' \textit{intrinsic} reasoning abilities. Moreover, we observe
that the presence of a CoT in the decoding path correlates with a higher
confidence in the model's decoded answer. This confidence metric effectively
differentiates between CoT and non-CoT paths. Extensive empirical studies on
various reasoning benchmarks show that the proposed CoT-decoding substantially
outperforms the standard greedy decoding.