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【報告】 19th TCCP Colloquium: How can we conceptualize ‘responsibility’ in the framework of the somatic marker hypothesis?

2010.04.19 筒井晴香, 西堤優, 脳科学と倫理

TCCP, or Tokyo colloquium of cognitive philosophy, is an English-only seminar which is held as a place for active discussion among UTCP fellows who are interested in neurophilosophy, neuroethics and various related topics.

The speaker of the 19th TCCP was NISHITSUTSUMI Yu, a collaborative research fellow of UTCP. She specializes in philosophy of mind and neuroethics. She has an interest in philosophical and ethical implications of the somatic marker hypothesis (SMH), a significant theory of our decision-making.

The title of Nishitsutsumi’s presentation was “How can we conceptualize ‘responsibility’ in the framework of the somatic marker hypothesis?” In this presentation, she elucidates what is it to be morally responsible for one’s action in the SMH framework.

First, Nishitsutsumi clarified the necessary condition for moral responsibility. One’s being responsible for an action presumes that one acted freely. One’s acting freely requires one’s having alternative possibilities among which one can choose by oneself (This analysis is based on H. Frankfurt’s claim). When we do have alternative possibilities and choose something among them, our choice is determined by our own beliefs and desires; namely, we make a rational choice among them. Making rational choice and carrying out the chosen option require self-control. Thus, self-control is necessary for being morally responsible for one’s action.

Then Nishitsutsumi introduced the SMH, which concerns our rational, self-controlled decision making. Acccording to SMH, emotion plays a crucial role in rational decision-making. Emotion contains “somatic states”, namely, bodily states which are automatically triggered by objects in the environment. When decision-making processes are active in our brain, brain states which carry information about somatic states work as markers of values of objects. Such brain states are a “somatic marker”, which biases decision-making process toward a choice which is expected to bring about the most benefit. Thus emotional bias is crucial when we make a decision.

A. Damasio holds the SMH on the basis of studies on brain-damaged patients who have lesions in the ventromedial prefrontal cortex (VMPFC). It is known that VMPFC patients have emotional deficits. They also lack the abilities of rational decision-making and self-control. A. Bechara et al. carried out a study using a gambling task. It showed that when making a choice, VMPFC patients lack emotional arousal which normal subjects do have. Examples like this suggest that the SMH is appropriate.

K. Burns and A. Bechara claim that there are two systems of decision-making, namely, the impulsive system and the reflective system. Emotion affects both, yet their characteristics are different. The former is fast and automatic; the latter is slow and deliberate. Burns and Bechara see self-control as the latter’s control over the former.

So, when the reflective system fails to keep the impulsive system under control, our self-control is lost. More precisely, states in which self-control is lost are divided into three types. The first is “impulsive system hyperactivity”, in which the impulsive system overwhelms the reflective system. The second is “reflective system dysfunction”, in which the reflective system does not work well. The third is “ego-depletion”, in which the resources of the reflective system are depleted. Here are examples of each type: a person who fails to quit smoking gives reasons to succumb to the temptation of smoking (impulsive system hyperactivity); VMPFC patients lose self-control because of the dysfunction of the reflective system (reflective system dysfunction); experiments shows that self-control becomes weak while resisting a temptation, after engaging in difficult tasks, or even in the decrease of glucose (ego-depletion). These examples suggest that losing self-control is not so unfamiliar to us.

Although moral responsibility requires self-control, we sometimes lose self-control. This may prompt a worry that we can cast moral responsibility on others much less than we can imagine. To such a worry, Nishitsutsumi claims that although we may not be morally responsible for our action without self-control, we are morally responsible for bringing ourselves to such states. For instance, suppose that a drug addict committed murder in an addicted state. Since she was in a state of little self-control, she might not be morally responsible for the murder. Yet if she did it rationally and under self-control, she is morally responsible for consuming the drug.

Nishitsutsumi’s presentation is intriguing in that it suggests the need of rethinking our understanding of responsibility. When we hear about drug addicts’ doing anything to obtain and consume drugs, we often think it is too foolish to understand. We, however, cannot necessarily conclude that they are totally foolish or are to be blamed by their foolishness. They are in a state without self-control.

One point I am concerned about is that all the talk seems to be about responsibility in general and not about moral responsibility per se. I wonder whether taking morality into account does not require any special consideration in addition to talking about responsibility in general.

Another point is that although dual-process theories of human decision making are popular, they are not accepted with no debate. Criticisms toward certain dualistic conceptions of human decision making are the theme of the next TCCP.

(TSUTSUI Haruka)

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