  Large Language Models (LLMs) have demonstrated good performance in many
reasoning tasks, but they still struggle with some complicated reasoning tasks
including logical reasoning. One non-negligible reason for LLMs' suboptimal
performance on logical reasoning is their overlooking of understanding logical
fallacies correctly. To evaluate LLMs' capability of logical fallacy
understanding (LFU), we propose five concrete tasks from three cognitive
dimensions of WHAT, WHY, and HOW in this paper. Towards these LFU tasks, we
have successfully constructed a new dataset LFUD based on GPT-4 accompanied by
a little human effort. Our extensive experiments justify that our LFUD can be
used not only to evaluate LLMs' LFU capability, but also to fine-tune LLMs to
obtain significantly enhanced performance on logical reasoning.
