Abstract: Investigating the subjectivity of moral intuition helps guide people to better deal with moral disputes. This article prioritizes a summary of the background for moral dilemmas, based on which the relationship between moral intuition and emotional factors. With an emphasis on its supportive evidence, it further explains the subjectivity of moral intuition with the Modular Myopia Hypothesis.
One of the research hotspots of contemporary moral psychology is to use “the Trolley problem” thought experiment to explore how people would make moral decisions when facing a dilemma. Brain imaging and neuropathology research evidence show that the emotional response caused by the ventromedial prefrontal cortex and amygdala affect people's moral judgments. In the moral dilemma, moral intuition leads to deontological judgments, and moral reasoning leads to utilitarian judgments. The research on the Trolley Problem identified that personal force and means/side effects are two important factors affecting people's intuitive judgment, but only the combination of these two factors would produce a stable impact. With the harm occurs as a mere side effect of personal force, it is relatively morally acceptable. So is when harm is used as a means to achieve a greater good, with no personal force. Nevertheless, harming as a means to achieve a goal with personal force is considered to be less acceptable than the previous ones. These studies show that moral intuition is strongly subjective. In the Trolley Problem, moral intuition is highly vigilant to the use of personal force and intentional harm, but less sensitive to harm caused by personal force or side effects.
Researcher proposed Modular Myopia Hypothesis under the framework of dual processing theory to explain the impact of personal force, means, and side effects on moral intuition. The hypothesis believes that there is a cognitive subsystem present in the human brain. It is a “module” that monitors our planned behavior and sound an emotional alert when it detects a harmful event in an action plan. However, this action-plan inspector is a relatively simple, “single-channel” system that is not able to keep track of multiple causal chains simultaneously. Therefore, when people intended to harm others to achieve a goal, the harm plan is located on the primary causal chain, the monitoring mechanism in the cognitive subsystem can detect and release an emotional alarm bell, alert to harmful behaviors. By contrast, if the harm is caused as a side effect, the harm is located on the secondary causal chain. Due to the limitation of the cognitive resources of the monitoring and reviewing system, the harmful side effect escapes monitoring, failing to trigger emotional alarms, as the system is “myopic”, unable to recognize the harm caused by side effects. Modular Myopia Hypothesis shows that in similar moral situations, seemingly irrelevant ethical factors may become the key to trigger people's emotional alarms in the brain, leading to completely different judgments and thus reducing the reliability of moral intuition. Without moral intuition as an objective reminder, one should not just rely on intuition as the sole basis for action in the face of moral disputes in real life.

Key words: moral dilemma, moral intuition, emotions, modular myopia hypothesis