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A Dual Process Theory of Ethical Judgement

Dual process theories of moral psychology claim that moral abilities involve two, or more, processes that are independent and divergent. They are independent in the sense that the conditions which influence whether they occur and which outputs they generate do not completely overlap. And they are divergent in the sense their outputs can conflict (given a single scenario, one process’ output imply rightness whereas the others’ implies wrongness).

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Please Answer This Dilemma First

The recording and slides make use of the following dilemma. Please answer it before you start.

‘You are part of a group of ecologists who live in a remote stretch of jungle. The entire group, which includes eight children, has been taken hostage by a group of paramilitary terrorists. One of the terrorists takes a liking to you. He informs you that his leader intends to kill you and the rest of the hostages the following morning.

‘He is willing to help you and the children escape, but as an act of good faith he wants you to kill one of your fellow hostages whom he does not like. If you refuse his offer all the hostages including the children and yourself will die. If you accept his offer then the others will die in the morning but you and the eight children will escape.

‘Would you kill one of your fellow hostages in order to escape from the terrorists and save the lives of the eight children?’ (Koenigs et al., 2007)

Why This Dual-Process Theory?

Greene offers an elaborate dual-process theory of ethical cognition, one which incorporates controversial claims about consequentialism and emotion.1 As these claims are neither essential features of a dual-process theory nor necessary for the overall argument we are developing (see Greene contra Ethics (Railgun Remix)), we may consider a stripped-down dual process theory instead.

The Stripped-Down Dual-Process Theory

According to this theory:

Two (or more) ethical processes are distinct in this sense: the conditions which influence whether they occur, and which outputs they generate, do not completely overlap.

One process is faster than another: it makes fewer demands on scarce cognitive resources such as attention, inhibitory control and working memory.

A key feature of the stripped-down dual-process theory is its theoretical modesty: it involves minimal commitments concerning the particular characteristics of the processes. Identifying characteristics of the process is a matter of discovery.

What Does the Dual-Process Theory Predict?

To make use of existing evidence, we have to add an auxiliary assumption to the dual-process theory:

The slow process is responsible for characteristically consequentialist responses; the fast for other responses.2

Prediction 1: Increasing cognitive load will selectively slow consequentialist responses. This prediction has been confirmed (Greene, Morelli, Lowenberg, Nystrom, & Cohen, 2008).

Prediction 2: Limiting the time available to make a decision will reduce consequentialist responses. This prediction also appears to have been confirmed:

‘The model detected a significant effect of time pressure, p = .03 (see Table 1), suggesting that the slope of utilitarian responses was steeper for participants under time pressure. […] participants under time pressure gave less utilitarian responses than control participants to scenarios featuring low kill–save ratios, but reached the same rates of utilitarian responses for the highest kill–save ratios’ (Trémolière & Bonnefon, 2014, p. 927).3

On the face of it, then, the dual-process theory appears well supported by evidence (and Greene, 2014 cites much further evidence). We may therefore accept it for now.

Of course you will need to evaluate the evidence properly (see Moral Intuitions and Emotions: Evaluating the Evidence) before you can claim to know whether or not the dual-process theory is true. We will consider some more evidence for, and against, the dual-process theory next week (look out especially for process dissociation).

Other Dual-Process Theories of Ethical Cognition

Dual-process theories of ethical cognition are widely endorsed but come in many varieties. All of the following are elaborations of the stripped-down dual-process theory above.

Cushman’s Dual-Process Theory

Cushman supplements the core idea of a dual-process theory with a distinction between model-free and model-based learning:

‘the functional role of value representation in a model-free system is to select actions without any knowledge of their actual consequences, whereas the functional role of value representation in a model-based system is to select actions precisely in virtue of their expected consequences’ (Cushman, 2013, p. 285).

Cushman also proposes that a good dual-process theory should explain patterns of judgements on dilemmas like the trolley problems, and that this requires appeal to distinction between model-free and model-based:

‘It is the contrast between model-free and model-based systems—or between action- and outcome-based valuation—that can explain the conflict engendered by moral dilemmas’ (Cushman, 2013, p. 285).

We consider Cushman’s proposal in Dual Process Theory and Auxiliary Hypotheses, where a quarter of it is adopted.

Kumar’s Dual-Process Theory

Kumar proposes what he calls a ‘minimalist’ dual-process theory:

‘A minimalist model says that two types of processes generate moral judgements. Type 1 processes are fast, spontaneous, unconscious, and involve emotional processing; type 2 processes are slow, controlled, conscious, and involve reasoned processing. In short, some moral judgements arise as a flash of feeling, while others issue from conscious deliberation’ (Kumar, 2016, p. 791).

This is not very different from the stripped-down theory I offered. So why not just use Kumar’s theory rather than making my own?4 In my view, it is not minimalist enough: there is little evidence on consciousness, control or speed; nor do we know enough about the phenomenology to postulate ‘a flash of feeling’.

Interestingly, Kumar does not accept Greene’s proposed link between fast processes and characteristically consequentialist responses. He does, however, link the fast processes to emotions:

’Each process type gives rise to one element of moral judgement: type 1 processes generate moral emotions and type 2 processes generate moral beliefs. A minimalist model also explains conflict cases’ (Kumar, 2016, p. 792).

Defending this claim requires finding some evidence for the link. My view is that while emotion probably plays different roles in fast and slow processes, it is likely to feature in both (as Cushman, 2013 suggests). For this reason I take Kumar’s bet on fast/slow linking to emotions/beliefs to be risky. And it is not required to generate predictions currently being tested.

Haidt’s Dual-Process Theory

Haidt’s Social Intuitionist Model of Moral Judgement (which is a part of Moral Foundations Theory; see Moral Foundations Theory: An Approach to Cultural Variation) could be interpreted as a kind of dual-process theory because it distinguishes intuition and reasoning as two kinds of process.

As we saw, the Social Intuitionist Model of Moral Judgement involves a variety of further claims—such as that ‘moral reasoning is done primarily for socially strategic purposes’ (Graham et al., 2013, p. 66)—which are not essential features of a dual-process theory.5

Two Systems?

Although two systems theories are sometimes understood as making claims over and above those of a dual-process theory (e.g. Bertram Gawronski & Trope, 2014), others do not make any distinction:

‘We use the term “system” only as a label for collections of cognitive processes that can be distinguished by their speed, their controllability, and the contents on which they operate’ (Kahneman & Frederick, 2005, p. 267).


automatic : On this course, a process is _automatic_ just if whether or not it occurs is to a significant extent independent of your current task, motivations and intentions. To say that _mindreading is automatic_ is to say that it involves only automatic processes. The term `automatic' has been used in a variety of ways by other authors: see Moors (2014, p. 22) for a one-page overview, Moors & De Houwer (2006) for a detailed theoretical review, or Bargh (1992) for a classic and very readable introduction
characteristically consequentialist : According to Greene, a judgement is characteristically consequentialist (or characteristically utilitarian) if it is one that in ‘favor of characteristically consequentialist conclusions (eg, “Better to save more lives”)’ (Greene, 2007, p. 39). According to Gawronski et al. (2017, p. 365), ‘a given judgment cannot be categorized as [consequentialist] without confirming its property of being sensitive to consequences.’
characteristically deontological : According to Greene, a judgement is characteristically deontological if it is one that in ‘favor of characteristically deontological conclusions (eg, “It’s wrong despite the benefits”)’ (Greene, 2007, p. 39). According to Gawronski et al. (2017, p. 365), ‘a given judgment cannot be categorized as deontological without confirming its property of being sensitive to moral norms.’
cognitively efficient : A process is cognitively efficient to the degree that it does not consume working memory and other scarce cognitive resources.
David : ‘David is a great transplant surgeon. Five of his patients need new parts—one needs a heart, the others need, respectively, liver, stomach, spleen, and spinal cord—but all are of the same, relatively rare, blood-type. By chance, David learns of a healthy specimen with that very blood-type. David can take the healthy specimen's parts, killing him, and install them in his patients, saving them. Or he can refrain from taking the healthy specimen's parts, letting his patients die’ (Thomson, 1976, p. 206).
dual-process theory : Any theory concerning abilities in a particular domain on which those abilities involve two or more processes which are distinct in this sense: the conditions which influence whether one mindreading process occurs differ from the conditions which influence whether another occurs.
Edward : ‘Edward is the driver of a trolley, whose brakes have just failed. On the track ahead of him are five people; the banks are so steep that they will not be able to get off the track in time. The track has a spur leading off to the right, and Edward can turn the trolley onto it. Unfortunately there is one person on the right-hand track. Edward can turn the trolley, killing the one; or he can refrain from turning the trolley, killing the five’ (Thomson, 1976, p. 206).
fast : A fast process is one that is to some interesting degree automatic and to some interesting degree cognitively efficient. These processes are also sometimes characterised as able to yield rapid responses.
Since automaticity and cognitive efficiency are matters of degree, it is only strictly correct to identify some processes as faster than others.
The fast-slow distinction has been variously characterised in ways that do not entirely overlap (even individual author have offered differing characterisations at different times; e.g. Kahneman, 2013; Morewedge & Kahneman, 2010; Kahneman & Klein, 2009; Kahneman, 2002): as its advocates stress, it is a rough-and-ready tool, not the basis for a rigorous theory.
Moral Foundations Theory : The theory that moral pluralism is true; moral foundations are innate but also subject to cultural learning, and the Social Intuitionist Model of Moral Judgement is correct (Graham et al., 2019). Proponents often claim, further, that cultural variation in how these innate foundations are woven into ethical abilities can be measured using the Moral Foundations Questionnare (Graham, Haidt, & Nosek, 2009; Graham et al., 2011). Some empirical objections have been offered (Davis et al., 2016; Davis, Dooley, Hook, Choe, & McElroy, 2017; Doğruyol, Alper, & Yilmaz, 2019). See Moral Foundations Theory: An Approach to Cultural Variation.
slow : converse of fast.
Social Intuitionist Model of Moral Judgement : A model on which intuitive processes are directly responsible for moral judgements (Haidt & Bjorklund, 2008). One’s own reasoning does not typically affect one’s own moral judgements, but (outside philosophy, perhaps) is typically used only to provide post-hoc justification after moral judgements are made. Reasoning does affect others’ moral intuitions, and so provides a mechanism for cultural learning.
trolley problem : ‘Why is it that Edward may turn that trolley to save his five, but David may not cut up his healthy specimen to save his five?’ (Thomson, 1976, p. 206).


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  1. See Paxton & Greene, 2010 for a compact overview of Greene’s theory. The theory has been presented in a variety of different ways (see, for example, Cushman, Young, & Greene (2010) for an alternative presentation). 

  2. Greene (2014) suggests that the fast process is responsible for characteristically deontological responses, but this further assumption is not required to generate the predictions considered here. 

  3. Later we will consider an alternative interpretation of the same findings due to Gawronski, Conway, Armstrong, Friesdorf, & Hütter (2018, p. 1006)

  4. The stripped-down dual-process theory not strictly speaking mine. It was developed jointly with Ian Apperly, Jason Low and Hannes Rakoczy. 

  5. Paxton & Greene (2010, pp. 513–4) offer a concise comparison: ‘there are two critical differences between Haidt’s SIM and Greene’s dual-process model. First, while the SIM posits that reasoned judgment within an individual is, ‘‘rare, occurring primarily in cases in which the intuition is weak and processing capacity is high,’’ Greene’s dual-process model allows that moral reasoning—especially utilitarian⁄consequentialist reasoning—may be a ubiquitous feature of moral common sense. Second, according to the SIM, social influence on moral judgment only occurs when one person succeeds in modifying another’s intuition.’