伊藤仁齋（1627-1705）在日本儒學思想史上所享的崇高地位，主要是因為其儒學思想最初濫觴於非功利主義色彩相當濃厚的朱子學體系，最終卻能在朱子學居壓倒性主流的環境下，於江戶元祿年間（1688-1703）開創出反朱子學的「古義學派」。然而，其思想體系內亦有諸多自相矛盾而無法自圓其說之處，尤其是有關「至聖孔子」與「亞聖孟子」之間對「功利」問題看法不同的質疑，伊藤仁齋始終依違於二者之間，捉襟見肘，無法提出圓融而會通雙聖的做法。這種思想體系漏洞的產生，一方面很可能來自於仁齋無法完全擺脫險峻的政治情勢，尤其是五代將軍德川綱吉畸形政治的壓力；另一方面，仁齋在七十三年的生命裡，也未能徹底跳脫兩千年儒學傳統性的內在束縛。

Though his ideas and thoughts originated from Zhuzi (朱子) himself, ironically, Ito Jinsai’s intellectual fame came from his anti-Zhuzi stance, in a period of iron fist rule which was based on the ideology of Zhuzi. While Zhuzism is anti-utilitarianism, Ito Jinsai became more and more of a utilitarian until the end of his life in the year 1705.In Jinsai’s ideas and thought system, there were many mutually inconsistent parts. This article shows that these mutually inconsistent parts could be closely compared to those between Confucius and Mencius. Until his last day, he still could not solve this inconsistency problem himself. This article analyzes why Ito Jinsai could not solve this problem. Some say Confucius was a utilitarian while Mencius was an anti-utilitarian. Jinsai looked up to Confucius’ teaching with the highest regard and respect. He also saw Mencius as the most perfect interpreter of Confucius, and he did not differentiate between them. There may be two reasons for this. Firstly, he was afraid of the then extremely strict rule of the 5th generation Shogun - [Tokugawa, Tsunayoshi] – a believer in Zhuzi. Secondly, he still could not escape from the trap of one of Chinese Cultures biggest traditions, which closely bonded Confucius and Mencius together, without any inconsistencies.