Robert Paul Wolff, at his blog The Philosopher’s Stone, objects to the use of trolley problems and other stylized thought experiments in which various complications are waved aside. “I am quite convinced that these sorts of thought experiments are nonsense,” he says. Wisely, he adds: “but it is not so easy to say why.”

I think that trolley problems and the like are excellent philosophical tools. They are often defended as means by which to isolate the relevant moral variable to help us assess how it does and should operate in our thinking, and I agree with this defense entirely. Like any tools, though, these thought experiments are built for specific tasks. Just as it would be silly to criticize the use of hammer because one couldn’t build a whole house using it alone, likewise, it is silly to criticize the trolley problems because one couldn’t build a whole moral theory out of them alone. Yet I hear variants of that criticism often.

This does not seem to be Wolff’s objection. His objection is that we often can’t isolate the relevant moral variable, and that we haven’t “earned” the assumption that we can. He writes:

The process of abstraction on which the process of formal argument depends presupposes that we can precisely and accurately distinguish the several elements of a real world action in such a fashion as will permit us to detach them from one another in constructing hypotheticals.

For example:

It… assumes that we can use terms like “intention” as though they were the names of simple identifiable particulars that can be safely abstracted from the complex context in which they are normally embedded… all those philosophers talking about trolley cars suppose that we can identify… intentions in abstraction from the knowledge and circumstances in which they occur, so that we can judge the intentions independently of the actual consequences or the knowledge that actors should have had, or — and this is quite important — independently of the institutional, historical, and bureaucratic context of the actions.  And that, I suggest, is wrong. 

I’m not sure this is correct. It isn’t that those of us who use such examples think “we can identify intentions in abstraction from the knowledge and circumstances in which they occur,” but rather that, by considering a simplified case, we make make it much easier to talk about what an agent knows and what the relevant circumstances are. But leaving this aside, Wolff thinks that assuming away the difficulty he identifies is kind of a cheat:

Whenever one of those factors is cited by someone objecting to the hypothetical example, the person posing the example will wave a hand and say “I will assume that consideration is not operative here.”  Let me now say something peculiar, but really quite important.  The dismissal of the objection with a wave of the hand is too easy.  Not wrong, exactly, but too easy.  The right to set aside that consideration has not been earned, by hard study, by experience, by history, or by personal sacrifice.  Philosophy done that way requires no heavy lifting, so to speak.  You can be as ignorant as a new born babe and yet, with a fertile imagination, you think to brush aside the hard-won wisdom of those who have actually been trolley car conductors or military field commanders or operating room nurses or heavy equipment operators by abstracting from it.

I am sympathetic with the idea that some philosophical positions have to be earned. What comes to mind is the lazy relativism that some students enter an introductory moral philosophy class with. Relativism could be true, but these students certainly don’t know enough to know that. They haven’t “earned” their relativism.

But I wonder if this criticism really applies to philosophers who use and know the limitations of the trolley cases. What prompted Wolff to write his post was a move by Sam Harris in his recent exchange with Noam Chomsky. Maybe (I have no idea) Harris is willing to go directly from “you should pull the lever in bystander” to some judgment of a real agent in the real world, without any additional steps or considerations, but if so, that seems more an indictment of Harris than of the thought experiments. Most philosophers, it seems to me, know that a variety of epistemological obstacles lie on the path from thought experiment to real-world recommendation.

As for the “hard-won wisdom of…  trolley car conductors,” I will relate one story. A couple of years ago I found myself on a trolley in Memphis, Tennessee. This was a rare opportunity to get an expert opinion, readers, and I was not going to waste it. The trolley stopped and I approached the driver. I said: “Imagine the trolley car is out of control, speeding down the hill towards five people tied to the track and who will die when hit by it. The only options you have are to do nothing and let the trolley run its course, or turn the trolley onto a side track before it hits the five. Unfortunately, there is one person tied to the side track who you would kill by sending the trolley that way. What should you do?”

She answered, “That would never happen. There is an automatic fail-proof brake.”

“But suppose there wasn’t,” I said.

Eyeing me suspiciously, she said, “Why would I do that?” And with that she exited the parked trolley car.

Wise move, trolley driver. Wise move.

(image: photo from “Trolley report: MATA not following safety standards,” WREG News 3)

UPDATE (5/18/15): Professor Wolff elaborates on his critique in a new post.