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Dual process theory (moral psychology)

Theory of human moral judgment

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Through Morality, Emotion and Psychology

The dual-process theory has had significant influence on research in moral psychology. The original fMRI investigation proposing the dual process account has been cited in excess of 2000 scholarly articles, generating extensive use of similar methodology as well as criticism.

Core commitments

The dual-process theory of moral judgement asserts that moral decisions are the product of either one of two distinct mental processes.

  1. The automatic-emotional process is fast and unconscious, which gives way to intuitive behaviours and judgments. The factors affecting moral judgment of this type may be consciously inaccessible.
  2. The conscious-controlled process involves slow and deliberative reasoning. Moral judgments of this type are less influenced by the immediate emotional features of decision-making. Instead, they may draw from general knowledge and abstract moral conceptions, combined with a more controlled analysis of situational features.

Greene conducted neuroscientific experiments where subjects were confronted with ethical dilemmas revolving around the famous Philippa Foot's famous Trolley Case (see Figure 1):

In the standard version, a runaway trolley is headed for five people who will be killed if it proceeds on its present course. The only way to save these people is to press a button that will turn the trolley onto a side track, where it will run over and kill one person instead of five. Surveys suggest the general consensus among both philosophers and lay persons is that it is morally acceptable to save five lives at the cost of one.

In the footbridge version of the problem, the setup is similar. As before, a runaway trolley threatens to kill five people, but this time the reader is standing next to a large stranger on a footbridge in-between the trolley and the five people. The only way to save the five people is to push the stranger off the bridge onto the tracks below. He will die, but his body will stop the trolley from reaching the five people. In this case, surveys suggest the consensus is that it is not okay to push a stranger to his death to save five lives.

To explain the differences in intuitions here, Joshua Greene claims that the two processes can be linked to two classes of ethical theories respectively. He calls this the Central Tension Problem: Moral judgments that can be characterised as deontological are preferentially supported by automatic-emotional processes and intuitions. Characteristically utilitarian judgments, on the other hand, seem to be supported by conscious-controlled processes and deliberative reasoning. The footbridge dilemma involves the thought of pushing someone to their death in an "up close and personal" manner, which activates a strong emotional response. Hitting a switch, by contrast, is much more impersonal and therefore does not evoke an emotional response. Greene hypothesies that this difference in emotional response explains why people respond so differently to these two cases. People tend toward consequentialism in the case where the emotional response is low and tend toward deontology in the case in which the emotional response is high.

Camera analogy

As an illustration of his dual-process theory of moral reasoning, Greene compares the dual-process in human brains to a digital SLR camera which operates in two complementary modes: automatic and manual. A photographer can either employ the automatic "point-and-shoot" setting, which is fast and highly efficient, or adjust and refine settings in manual mode, which gives the photographer greater flexibility.

Dual-process moral reasoning is an effective response to a similar efficiency-flexibility trade-off. We often rely on our "automatic settings" and allow intuitions to guide our behaviour and judgement. In "manual mode", judgments draw from both general knowledge about "how the world works" and explicit understanding of special situational features. The operations of this "manual mode" system requires effortful conscious deliberation.

Greene concedes that his analogy has limited force. While a photographer can switch back-and-forth between automatic and manual mode, the automatic-intuitive processes of human reasoning are always active: conscious deliberations needs to "override" our intuitions. In addition to that, automatic settings of our brains are not necessarily "hard-wired", but can be changed through (cultural) learning.

Interaction between systems

There is lack of agreement on whether and how the two processes interact with one another. It is unclear whether deontological responders, for example, rely blindly on the intuitively cued response without any thought of utilitarian considerations or whether they recognise the alternative utilitarian response but, on consideration, decide against it. These alternative interpretations point to different models of interaction: a serial (or "default-interventionist") model, and a parallel model.

Serial models assume that there is initially an exclusive focus on the intuitive system to make judgements but that this default processing might be followed by deliberative processing at a later stage. Greene et al.'s model is usually placed within this category. In contrast, in a parallel model, it is assumed that both processes are simultaneously engaged from the beginning.

Models of the former category lend support to the view that humans, in an effort to minimise cognitive effort, will choose to refrain from the more demanding deliberative system where possible. Only utilitarian responders will have opted into it. This further implies that deontological responders will not experience any conflict from the "utilitarian pull" of the dilemma: they have not engaged in the processing that gives rise to these considerations in the first place. In contrast, in a parallel model both utilitarian and deontological responders will have engaged both processing systems. Deontological responders recognise that they face conflicting responses, but they do not engage in deliberative processing to a sufficient extent to enable them to override the intuitive (deontological) response.

Within generic dual process research, some scientists have argued that serial and parallel models fail to capture the true nature of the interaction between dual process systems. They contend that some operations that are commonly said to belong to the deliberative system can in fact also be cued by the intuitive system, and we need to think about hybrid models in light of this evidence. Hybrid models would lend support to the notion of a "utilitarian intuition" - a utilitarian response cued by the automatic, "emotion-driven" cognitive system.

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