Is experimental philosophy useless? (Part III)

In Part I and II I argued that even though experimental philosophers are generally wrong to assume that philosophers treat intuitions as evidence (which makes x-phi largely pointless), sometimes they are not wrong to make this assumption, and in those isolated cases their research is not pointless. This time I want to argue that x-phi can occasionally make sense, in a modest way, even when it’s based on wrong metaphilosophical assumptions. My example would be one of the most popular and also one of the most widely misunderstood philosophical problems of all time: the trolley* problem.

What is it and why do experimental philosophers believe it’s important to study people’s judgments about it? Here’s Joshua Greene**:

For the uninitiated, the Trolley Problem arises from a set of moral dilemmas, most of which involve tradeoffs between causing one death and preventing several more deaths. The descriptive problem is to explain why, as a matter of psychological fact, people tend to approve of trading one life to save several lives in some cases but not others. Consider the two most widely discussed cases (Thomson 1985): People responding to the standard switch case (a.k.a. bystander) tend to approve of hitting a switch that will redirect a trolley away from five and onto one. By contrast, people responding to the standard footbridge case tend to disapprove of pushing one person off a footbridge and in front a trolley, killing that person but saving five further down the track. The normative problem is to explain when and why we ought to approve of such one‐for‐many tradeoffs. The longstanding hope is that a solution to the normative Trolley Problem will reveal general moral principles. Such principles, in turn, may apply to challenging, real‐world moral problems such as those encountered in the domains of bioethics (Foot 1978; Kamm 2001), war (McMahan 2009), and (most recently) the design and regulation of autonomous machines such as self‐driving cars (Wallach and Allen 2008).

The normative and descriptive Trolley Problems are closely related. The normative Trolley Problem begins with the assumption that our natural responses to these cases are generally, if not uniformly, correct. Thus, any attempt to solve the normative Trolley Problem begins with an attempt to solve the descriptive problem, to identify the features of actions that elicit our moral approval or disapproval. Once such features have been identified and we turn toward normative questions, there are two general possibilities.

First, we might find that the features to which our judgments are sensitive also appear, upon reflection, to be features to which they ought to be sensitive. Under these happy circumstances, the normative problem is essentially solved. Here, we simply reconfigure our descriptive psychological principles as normative moral principles (Mikhail 2011). For example, we translate “People judge the action to be morally acceptable if and only if…” into, “The action is morally acceptable if and only if…” A philosophy thus supported would not be proven correct from first principles. Instead, it would sway comfortably in the hammock of “reflective equilibrium,” supported by a network of “considered judgments” (Rawls 1971).

The second, more discomfiting possibility is that a better understanding of moral psychology will prompt us to reconsider many of our “considered judgments.” More specifically, science may teach us that some of our judgments are sensitive to features that, upon reflection, do not seem to matter morally. Likewise, we may find that our judgments are insensitive to moral features that, upon reflection, do seem to matter morally. Under these more complicated circumstances, a scientific understanding of moral judgment creates a problem and a corresponding opportunity. By moving some of our judgments out of the “reliable” box and into the “unreliable” box, we may find that the ones remaining in the “reliable” box point to new conclusions. (Or to old conclusions that have been widely dismissed.)

I think this is all misguided – scientific research of the kind that Greene is talking about is not able to bring us any closer to solving the “normative Trolley Problem”. Why? According to Greene, in order to evaluate statements like “it is morally permissible to pull the lever and divert the tram onto the side track” (call it the bystander judgment, BJ) or “it is not morally permissible to push the fat man off the bridge” (call it the footbridge judgment, FJ), we need to study cognitive processes that lead us to make these judgments. Either they track what’s morally relevant, or they don’t. If it turns out they don’t, then we have good reasons to doubt the truth of BJ and SJ.

The bystander case: is it permissible to divert the tram?

For example, according to one study on the trolley problem that Greene points to people seem to judge harmful actions to be more intentional and less acceptable when “personal force” (defined as a force “generated by the agent’s muscles, as when one pushes another with one’s hands or with a rigid object”) is applied. But this seems morally irrelevant. There may be a psychological difference between killing somebody using one’s bare hands and killing somebody by flipping a switch, but there’s no moral difference: both acts are equally wrong. If our psychological inclination to judge the use of “personal force” more harshly is the only reason why we think there’s a moral difference between the bystander case and the footbridge case, then BJ and FJ cannot both be true at the same time.

However note that in order to draw this conclusion, we must already know what counts as morally relevant before we start doing the x-phi research. And if we know what’s morally relevant prior to the research, what’s the point of doing it? The research can only reveal how many people make judgments like BJ or FJ or why they make them, but it will never reveal – or even help reveal – if these judgments are true. This is where Greene’s reasoning goes wrong: he conflates what’s needed to evaluate the judgments with what leads us to make them. And the reason why he makes this mistake is, I think, obvious: he’s a believer in the intuitions-are-evidence dogma. He thinks that it matters whether BJ and FJ are intuitive, as there exists a philosophical method of treating the intuitiveness of a judgment as something that makes this judgment true***. However when we actually read the canonical texts that he himself refers to – like The Trolley Problem by Judith Jarvis Thomson – it turns out there’s nothing in there that justifies this view.

The footbridge case: is it permissible to push the man off the bridge?

Let’s take a closer look at Thomson’s paper. Her inquiry starts off with a certain working hypothesis: that BJ and FJ are true and her job is to find out what makes the difference between them. She eventually discovers the morally relevant factor (or so she thinks): deflecting the tram is permissible because it doesn’t constitute an infringement of anyone’s rights, but pushing the fat man off the bridge is impermissible because it constitutes an infringement of what she calls a stringent right of a person. She offers a complex argument to support this view.

Someone may ask: “Ok, fine, but where does the initial hypothesis come from? She says she had asked a number of people about both cases and they all agreed with BJ and FJ****. Doesn’t it show that she cares about people’s intuitions?” The answer is: she may care about people’s intuitions, but definitely not in the way experimental philosophers think she does. It’s true that a couple of times in her article Thomson mentions consulting her friends about their judgments on different trolley-related scenarios. This, however, seems to have only led numerous readers astray. They’ve convinced themselves that for Thomson something is true because her friends say so, or because it seems true to them. But this is nonsense. What makes BJ and FJ true, according to Thomson, is not the fact that BJ and FJ are intuitive, or the fact that her friends agree with BJ and FJ. It’s the fact that, again, in the bystander case we’re not infringing on anyone’s right by pulling the lever, but in the footbridge case we are infringing on the fat man’s right by making him fall off.

So it’s simply not the case that Thomson relies on intuitions as evidence for her claims. However it may be fair to say she relies on intuitions to select the hypotheses to work with. The reason why she asks her friends for their opinions is that she believes those opinions are not completely off. She generally assumes her friends are on to something important, that they have good reasons to think what they think, but they might not be able to articulate them.*****

And this brings us to why, despite all the metaphilosophical confusion in the x-phi circles, I don’t think x-phi research on trolley cases is utter rubbish. I think it can help us determine which lines of trolley-inquiry are worth pursuing, and which trolley-related philosophical conclusions are worth re-examining. If in some situations, as experimental philosophers point out, our cognitive processes make us see a moral difference where there isn’t one, trying to explain or justify this difference would be a waste of time. Hence learning more about cognitive processes behind people’s moral judgments can allow us to plan our philosophical research more efficiently – which is important, as there are only so many philosophers and they have only so much time.

To sum up: if a day comes when experimental philosophers realise their project hinges on completely false views about philosophical methodology, for some of them it might not change that much: they’ll change their mind about the philosophical significance of what they do, but otherwise they’ll just carry on with their work. However for most of them the change is going to be more dramatic – in order to answer the questions they want to answer, they’ll have to sit back in their armchairs.


* Just in case I have any British readers who are not familiar with the scenario: in American English “trolley” means a tram (and what the Brits call a trolley is called a cart in the US). Teaching philosophy undergrads has taught me this is not always clear.

** Actually I’m not sure if Greene identifies as an experimental philosopher, and the empirical research on the trolley problem that he refers to sometimes is, and sometimes isn’t labelled as x-phi. Anyway, what I’m quoting here has been published in “A Companion to Experimental Philosophy”, and I think it nicely captures the way experimental philosophers commonly think about the point of studying trolley cases.

*** A little clarification: “using intuitions as evidence” is ambiguous between (1) “the intuitiveness of p is used as evidence for p” and (2) “the intuitiveness of p is used as evidence for q”. When I say that Greene believes in the dogma, what I mean is that he believes in (1). When I say that experimental philosophers are sometimes not wrong to assume that intuitions are used as evidence, what I mean is they are sometimes not wrong to think that (2), but they are always wrong to think that (1).

**** I’m simplifying a little bit to make it more readable. Actually Thomson says she didn’t ask about the bystander case, but about the original trolley case (aka the trolley driver case), first introduced by Philippa Foot, which is quite similar, however it might differ from the bystander scenario in a morally important respect. Anyway, eventually she says she’s going to simply take it that BJ is true.

***** Note that sometimes (like in the city mayor version of the bystander case) those reasons turn out to be not so good, and Thomson argues that people she asked about the case are wrong. This conclusively shows she doesn’t understand her task as simply rationalising whatever people may come up with.

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