朱熹的思想究是一元論或是二元論？學者聚訟不息，似無定論。各種說法固然言之成理，持之有故，但我覺得，如果能夠把觀點層次分開，許多矛盾衝突或者可以化解大半。我的意思是，由形上構成的角度看，朱熹是二元論；由功能實踐的角度看，朱熹對於終極的體證偏離於孟子的直貫型態，確有一間之隔。但朱熹所以主張二元，是為了要保住理的超越性。陽明以降的一元論容易陷落在內在之中，造成超越意義的減煞。從工夫論的觀點看，朱熹對陸象山的追隨者的批評，實涵有一種先見，恰好可以針對王門後學的蕩越有所針砭，而有其不可忽視的意義。

　　　　　The question has troubled scholar's minds for years . There does not seem to be a good solution accepted by all . In this article I propose to see the problem from two different perspectives : ontological and functional . Only when both perspectives are taken into account , can a coherent picture of Chu Hsi's thinking emerge . As Chu His maintains that li 理（principle） and chi 氣（vital force ）must not be mixed up with each other , he is to be regarded as a dualist from an ontological point of view . But as he also maintains that li and ch'i work closely together to the extent that they cannot be separated from each other , he is to be seen as a monist from a functional point of view . The two perspectives are not contradictory but complementary to each other .Chu His's dualism is inconsistent with Menciu's thinking ; actually he does not seem to be able to fully appreciate the latter's insight .But Chu Hsi's approach has its significance from the perspective of self-discipline , as it can safeguard the transcendence of li and help to avoid the pitfalls of a monism that sees immanence only ; he seems to have foreseen the bad influence of some of the impudent followers of Wang Yang-ming .