Part of the sequence: Rationality and Philosophy

Consider these two versions of the famous trolley problem:

Stranger: A train, its brakes failed, is rushing toward five people. The only way to save the five people is to throw the switch sitting next to you, which will turn the train onto a side track, thereby preventing it from killing the five people. However, there is a stranger standing on the side track with his back turned, and if you proceed to thrown the switch, the five people will be saved, but the person on the side track will be killed.

Child: A train, its brakes failed, is rushing toward five people. The only way to save the five people is to throw the switch sitting next to you, which will turn the train onto a side track, thereby preventing it from killing the five people. However, there is a 12-year-old boy standing on the side track with his back turned, and if you proceed to throw the switch, the five people will be saved, but the boy on the side track will be killed.

Here it is: a standard-form philosophical thought experiment. In standard analytic philosophy, the next step is to engage in conceptual analysis — a process in which we use our intuitions as evidence for one theory over another. For example, if your intuitions say that it is "morally right" to throw the switch in both cases above, then these intuitions may be counted as evidence for consequentialism, for moral realism, for agent neutrality, and so on.

Alexander (2012) explains:

Philosophical intuitions play an important role in contemporary philosophy. Philosophical intuitions provide data to be explained by our philosophical theories [and] evidence that may be adduced in arguments for their truth... In this way, the role... of intuitional evidence in philosophy is similar to the role... of perceptual evidence in science...

Is knowledge simply justified true belief? Is a belief justified just in case it is caused by a reliable cognitive mechanism? Does a name refer to whatever object uniquely or best satisfies the description associated with it? Is a person morally responsible for an action only if she could have acted otherwise? Is an action morally right just in case it provides the greatest benefit for the greatest number of people all else being equal? When confronted with these kinds of questions, philosophers often appeal to philosophical intuitions about real or imagined cases...

...there is widespread agreement about the role that [intuitions] play in contemporary philosophical practice... We advance philosophical theories on the basis of their ability to explain our philosophical intuitions, and appeal to them as evidence that those theories are true...

In particular, notice that philosophers do not appeal to their intuitions as merely an exercise in autobiography. Philosophers are not merely trying to map the contours of their own idiosyncratic concepts. That could be interesting, but it wouldn't be worth decades of publicly-funded philosophical research. Instead, philosophers appeal to their intuitions as evidence for what is true in general about a concept, or true about the world.

In this sense,

We [philosophers] tend to believe that our philosophical intuitions are more or less universally shared... We... appeal to philosophical intuitions, when we do, because we anticipate that others share our intuitive judgments.

But anyone with more than a passing familiarity with cognitive science might have bet in advance that this basic underlying assumption of a core philosophical method is... incorrect.

For one thing, philosophical intuitions show gender diversity. Consider again the Stranger and Child versions of the Trolley problem. It turns out that men are less likely than women to think it is morally acceptable to throw the switch in the Stranger case, while women are less likely than men to think it is morally acceptable to throw the switch in the Child case (Zamzow & Nichols 2009).

Or, consider a thought experiment meant to illuminate the much-discussed concept of knowledge:

Peter is in his locked apartment and is reading. He decides to have a shower. He puts his book down on the coffee table. Then he takes off his watch, and also puts it on the coffee table. Then he goes into the bathroom. As Peter's shower begins, a burglar silently breaks into Peter's apartment. The burglar takes Peter's watch, puts a cheap plastic watch in its place, and then leaves. Peter has only been in the shower for two minutes, and he did not hear anything.

When presented with this vignette, only 41% of men say that Peter "knows" there is a watch on the table, while 71% of women say that Peter "knows" there is a watch on the table (Starman & Friedman 2012). According to Buckwalter & Stich (2010), Starmans & Friedman ran another study using a slightly different vignette with a female protagonist, and that time only 36% of men said the protagonist "knows," while 75% of women said she "knows."

The story remains the same for intuitions about free will. In another study reported in Buckwalter & Stich (2010), Geoffrey Holtman presented subjects with this vignette:

Suppose scientists figure out the exact state of the universe during the Big Bang, and figure out all the laws of physics as well. They put this information into a computer, and the computer perfectly predicts everything that has ever happened. In other words, they prove that everything that happens has to happen exactly that way because of the laws of physics and everything that's come before. In this case, is a person free to choose whether or not to murder someone?

In this study, only 35% of men, but 63% of women, said a person in this world could be free to choose whether or not to murder someone.

Intuitions show not only gender diversity but also cultural diversity. Consider another thought experiment about knowledge (you can punch me in the face, later):

Bob has a friend Jill, who has driven a Buick for many years. Bob therefore thinks that Jill drives an American car. He is not aware, however, that her Buick has recently been stolen, and he is also not aware that Jill has replaced it with a Pontiac, which is a different kind of American car. Does Bob really know that Jill drives an American car, or does he only believe it?

Only 26% of Westerners say that Bob "knows" that Jill drives an American car, while 56% of East Asian subjects, and 61% of South Asian subjects, say that Bob "knows."

Now, consider a thought experiment meant to elicit semantic intuitions:

Suppose that John has learned in college that Gödel is the man who proved... the incompleteness of arithmetic. John is quite good at mathematics and he can give an accurate statement of the incompleteness theorem, which he attributes to Gödel as the discoverer. But this is the only thing that he has heard about Gödel. Now suppose that Gödel was not the author of this theorem. A man called "Schmidt"… actually did the work in question. His friend Gödel somehow got a hold of the manuscript and claimed credit for the work, which was thereafter attributed to Gödel... Most people who have heard the name "Gödel" are like John; the claim that Gödel discovered the incompleteness theorem is the only thing that they have ever heard about Gödel.

When presented with this vignette, East Asians are more likely to take the "descriptivist" view of reference, believing that John "is referring to" Schmidt — while Westerners are more likely to take the "causal-historical" view, believing that John "is referring to" Gödel (Machery et al. 2004).

Previously, I asked:

What would happen if we dropped all philosophical methods that were developed when we had a Cartesian view of the mind and of reason, and instead invented philosophy anew given what we now know about the physical processes that produce human reasoning?

For one thing, we would never assume that people of all kinds would share our intuitions.

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