SelfCheck: Using LLMs to Zero-Shot Check Their Own Step-by-Step Reasoning

The recent progress in large language models (LLMs), especially the invention of chain-of-thought prompting, has made it possible to automatically answer questions by stepwise reasoning. However, when faced with more complicated problems that require non-linear thinking, even the strongest LLMs make mistakes. To address this, we explore whether LLMs are able to recognize errors in their own step-bystep reasoning, without resorting to external resources. To this end, we propose SelfCheck, a general-purpose zero-shot verification schema for recognizing such errors. We then use the results of these checks to improve question-answering performance by conducting weighted voting on multiple solutions to the question. We test SelfCheck on three datasets-GSM8K, MathQA, and MATH-and find that it successfully recognizes errors and, in turn, increases final answer accuracies. INTRODUCTION Recent years have witnessed dramatic changes in the areas of NLP and AI brought on by significant advances in LLMs. From GPT-3 (Brown et al., 2020), PaLM (Chowdhery et al., 2022), Llama (Touvron et al., 2023) and Falcon (Almazrouei et al., 2023) to GPT-4 (OpenAI, 2023) and PaLM-2 (Google, 2023), the increasing model sizes and exploding amount of training data have empowered LLMs to achieve human-level performance on a large range of tasks, including summarization, translation, and question answering. The invention of Chain-of-Thought prompting (CoT, Wei et al. (2022)) has further enhanced LLMs' ability to solve complex problems by generating step-by-step solutions. However, the performance of even the largest LLMs is still unsatisfactory on more difficult reasoning problems. For example, GPT-4 with CoT prompting only correctly answers 42.5% of problems in the MATH dataset (Bubeck et al., 2023; Hendrycks et al., 2021), which is far below human level. Such problems require careful and extensive multi-step reasoning to solve, and LLMs are consequently prone to make mistakes: even though their error rate on individual steps may be low, the probability of generating at least one erroneous step can still be quite high, undermining the final answer. Recent works have tried to overcome this limitation by checking for errors in these step-by-step solutions (Cobbe et al., 2021; Li et al., 2022; Ling et al., 2023) . Such checks can then be used to provide confidence scores in answers and select between different possible alternatives. This checking has typically been performed either by using an external verification model (