The distinction between moral monism and moral pluralism has been reflected in the early vision of moral philosophy. Moral pluralism can be traced back to moral relativism, which holds that there is no universal moral principle. And any moral value applies only within certain cultural boundaries and individual value systems. However, moral universalism, a monistic ethical position, holds that there are universal ethics that apply to all people. In recent years, the above theoretical confrontations have entered the field of moral psychology. The dispute between monism and pluralism is one of the most active theoretical controversies in the field of moral psychology in recent years. Moral monism holds that all external moral-related phenomena and internal moral structures can be explained by one factor. The representative theories are stages theory of moral development and dyadic morality theory and so on. On the other hand, moral pluralism holds that morality cannot be explained by a single factor, but there are many heterogeneous moral dimensions, which are culturally sensitive. The representative theories include the triadic moral discourse theory, the relational model theory and the moral foundations theory and so on.
Among them, the dyadic morality theory put forward by Kurt Gray et al. and the moral foundation theory put forward by Jonathon Haidt are the typical representatives of the disputes between monism and pluralism. Gray et al. argued that harm is the most powerful factor in explaining moral judgments and moral judgments about harm are more intuitive. Moreover, people with different political orientations reach a consensus that harm is the core of moral judgments. On the contrary, Haidt et al. believed that people of different political orientations, cultures and social classes is manifested with different moral foundations, and the moral foundations scale has good construct validity, discriminant validity, practical validity, etc. The disputes between the two theories mainly focus on the explanatory power of harm, the harmfulness of moral dumbfounding, modularity views and the problem of purity. Specifically, Gray et al. argued that moral dumbfounding stems from biased sampling that confounds content with weirdness and severity, rather than purity violation. They also believed that the so-called "harmless wrongs" can be explained by perceived harm. Importantly, purity cannot be regarded as an independent construct of morality. Moreover, there is few evidence to support the modular claims. Nevertheless, Haidt et al. believed that moral monism oversimplifies the connotations of morality. The different moral foundations are not " Fodorian modularity", but more flexible and overlapping "massive modularity". Furthermore, plenty of evidence supported purity as an independent moral foundation.
Future research should be carried out in the following aspects. First of all, morality must need a clearer definition. To ensure the validity of moral research, future research should try to define moral concepts more clearly and should ensure that only one construct is tested at a time. Without ensuring that the situation clearly reflects a certain moral dimension, it is difficult for researchers to pinpoint which moral dimension influences people’s moral judgments. Secondly, in addition to paying attention to the disputes between monism and pluralism, we also need to separate from the disputes, take an objective view of the different characteristics of the controversies, learn from each other and complement each other, so as to promote the development of moral psychology. Specifically, moral monism emphasizes the simplicity of moral constructs and the accuracy of measurement, while pluralism emphasizes the understanding of the nature of morality among people in different cultures. These are two different theoretical constructs and explanations of the nature of morality. Future research should combine the advantages of moral monism and moral pluralism, and try to adopt realistic situations with high ecological validity, so as to construct a more perfect integrated theoretical model. Last but not the least, most previous empirical studies have been dominated by the "WEIRD (Western, Educated, Industrialized, Rich and Democratic)” sample. Future research should urgently consider the possibility of carrying out morality research in different cultures, especially based on the Chinese culture to explore the nature of morality.
一元论与多元论之争是道德心理学领域近些年最为活跃的理论交锋之一。道德一元论认为所有外在的道德现象与内在的道德结构或原因都可以用一种因素来解释,代表理论为道德发展阶段论、对应道德理论等。道德多元论则认为道德不能只用一种单一的因素来解释,而是存在多个不同质的道德维度,且具有文化敏感性,代表理论为三元道德话语理论、关系模式理论以及道德基础理论等。
其中,格雷等人提出的对应道德理论和海特提出的道德基础理论是一元论与多元论之争的典型代表。格雷等人认为伤害是解释道德判断最强有力的因素,而且关于伤害的道德判断更加直觉。此外,不同政治倾向的人皆认为伤害是道德认知的核心。反之,海特等人认为不同政治倾向、文化、社会阶层的人关注不同的道德基础,而且道德基础量表有良好的构念效度、区分效度、实用效度等。双方的论争主要集中在伤害的解释力、道德失声现象、模块化道德与洁净维度独立性等方面。具体而言,格雷等人认为道德失声源于伤害和情境怪异性,而不是洁净违背,而且洁净不可作为独立的道德维度。另外,没有证据支持模块化道德假说。但海特等人认为一元论过度简化了道德内涵。道德基础理论并非是五个“福多式模块”,而是更为灵活和重叠的“群集模块”。有大量证据支持洁净可以作为独立的道德基础。
未来研究应从如下几个方面开展。首先,道德需要一个更加清晰的界定。为保证道德研究的有效性,未来研究应尽可能做到将道德概念定义地更加清晰,应当确保每次只检验一种构念。如果不保证情境清晰地反应某种道德维度,则研究者很难精确指出哪种道德维度影响了人们的道德判断。其次,除了关注一元论与多元论本身的争议,我们也需从纷争中抽离出来,客观看待这两种道德取向研究的不同特点,彼此取长补短,以推动道德心理整体研究的发展。具体而言,一元论重视道德构念的简洁度以及测量的精确性,多元论则着重强调不同文化下的人群对于道德本质的理解。这是两种不同的建构理论和看待道德本质的方式。未来研究应该结合一元论与多元论研究彼此的优势,尽可能采用生态效度高的现实情境,从而建构出更为完善的整合式理论模型。最后,以往绝大多数实证研究却是以“怪异(WEIRD,指西方、受教育、工业化、富裕及民主)”样本为主导。未来研究应亟需考虑在不同文化下开展道德研究的可能性,尤其是针对中国本土文化的道德本质探究。