Interdisciplinary Research on Emotions in Neuroscience and Philosophy

Emotions and Social Interactions in a Neurobiology of Morals

Already in the 18th century, it has been a controversy between the philosophers David Hume and Immanuel Kant, whether man is an animal emotionale or rationale with regard to moral decision making. Hume proposed an emotivist approach to ethics (Hume 1777/1960), which Kant countered with his rationalist ethical theory (Kant 1785/1959). This issue has not been resolved until today, and has been discussed recently in moral psychology. Facilitated by the so-called "cognitive revolution" in psychology throughout the 1960s and 70s, moral psychologist Lawrence Kohlberg built his rationalist theory of moral reasoning (Kohlberg 1971; Kohlberg et al. 1983) on the ground-breaking research of the famous developmental psychologist Jean Piaget (Piaget 1932/1965). Similar to Piaget's four stages of cognitive development in the child, Kohlberg designed a system of six stages of moral development in man (for an overview, see Crain 1985, ch 7., freely available on the Internet), of which the last two steps, however, the so-called "postconventional morality," could only be reached through special teaching. Therefore, it is not surprising that Kohlberg founded specific schools in the United States of America that emphasized on the pupils' moral education.

This rational approach to moral decision making, nevertheless, has been contested by social intuitionists lately, supported by a general trend in neuroscience to investigate the contribution of emotions and intuitions (Damasio 1994; for a review, see Adolphs 2003) to hitherto exclusively cognitively understood mental processes. Among these contributions, moral psychologist Jonathan Haidt has developed the so-called “social intuitionist model,” which incorporates different intuitive, social, and cognitive links into a sophisticated theory of moral decision making (Haidt 2001).

Using the methods of human brain mapping, especially functional magnetic resonance imaging (fMRI), researchers have used special paradigms to investigate the neurobiology of moral decisions and evaluations (e.g. Greene et al. 2001; 2004; Heekeren et al. 2003; 2005; Moll et al. 2002; for reviews, see Greene & Haidt 2002; Moll et al. 2005). These new techniques of brain research offer a safe insight into the neurophysiological processes that are related to the subject's performance in such experiments. In our “animal emotionale” project, we investigate the contribution of emotional and social factors to moral decisions. One aim of the project is to identify regions, especially subregions of the medial prefrontal cortex (MPFC), that can be associated with emotional, theory of mind, and rational processes, respectively. Another aim is to go beyond mere correlations of brain activity with certain decision making strategies and to investigate the causal relations which the subregions of the MPFC exert on decision making related brain activations.

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