Barbara and Wally jumped into the taxi at Oxford station. "We're in a hurry," said Barbara. "We've just done London and are heading to Stratford-upon-Avon this afternoon. So please could you just show us the university and then bring us back to the station."
The taxi driver smiled to himself, set the meter running and looked forward to receiving a big fare.
He took them all round the city. He showed them the Ashmolean and Pitt Rivers museums, as well as the botanic gardens and the museums of natural history and the history of science. His tour took in not only the famous Bodleian library, but the lesser known Radcliffe, Sackler, and Taylor libraries too. He showed them all thirty-nine colleges as well as the seven permanent private halls. When he finally pulled up at the station, the meter showed a fare of £64.30.
"Sir, you are a fraud!" protested Wally. "You showed us the colleges, the libraries, and the museums. But damn you, we wanted to see the university!"
"But the university is the colleges, libraries, and museums!" replied the indignant cabbie.
"You expect us to fall for that?" said Barbara. "Just because we're American tourists doesn't mean we're stupid!"
Source: Chapter 1 of The Concept of Mind by Gilbert Ryle, 1949.
Baggini, J., The Pig That Wants to Be Eaten, 2005, p. 145.
This experiment isn't so much a question as it is a cunning demonstration of how many philosophers have been as dumb as these American tourists. Baggini, explains this very well and clearly, so let's turn the big reveal over to him. In his discussion of this thought experiment, Baggini said:
"[This is] a striking example of a form of fallacious thinking that even the smartest minds fall foul of. Barbara and Wally have made what the Oxford philosopher Gilbert Ryle called a category mistake. They have thought of Oxford University as though it were the same kind of thing as the colleges, libraries, and museums which comprise it: an institution housed in a specific building. But the university is not that kind of thing at all. There is no one place or building which you can point to and say, 'that is the university.' ... But that does not mean that the university is a ghostly presence that mysteriously unites all the colleges, libraries, and other parts of it. To think that would be to make another category mistake. It is neither a single material nor immaterial thing. We should not be misled by language and assume that because it is a singular noun it is a singular object."
From this origin of the category error term, we can see how clearly it applies to the differences that exist between abstract titles used for a group of things versus those concrete individual things themselves. I should point out, however, that philosophers have since extended the usage to also apply to any scenario where "a property is ascribed to a thing that could not possibly have that property." Metaphors are easy examples of this further usage. When we say something like, "the day flew by", that too is literally a category error since days aren't physical objects that move. Of course, we allow those figurative figures of speech because they aren't literally meant to be literal.
Anyway, an important application of this for philosophy comes when considering the dualism of Descartes, who, as I explained in my post on him, laid out the mind-body problem thusly:
Descartes...suggested that the body works like a machine, that it has the material properties of extension and motion, and that it follows the laws of physics, whereas the mind (or soul), on the other hand, was described as a nonmaterial entity that lacks extension and motion, and does not follow the laws of physics. Descartes argued that the mind interacts with the body at the pineal gland. This form of dualism proposes that the mind controls the body, but that the body can also influence the otherwise rational mind, such as when people act out of passion. Most of the previous accounts of the relationship between mind and body had been uni-directional.
That pineal gland conjecture turned out to be pure nonsense of course, but the rest of Descartes' idea was punctured by this week's thought experiment too. Once again, Baggini does a nice job of explaining how:
Ryle thought that the most common way of thinking about the mind made a similar category mistake. Again, we have a singular noun—the mind—and so we tend to think there must be a singular thing which the noun labels. ... [But] the mind is not a single object at all. To say something has a mind is to say it wants, desires, understands, thinks, and so on. Because we do all these things we say we have minds. But that doesn't require us to identify any object as being the mind. ... It's a neat solution to an age-old problem.
I'm inclined to agree with this. For me, such a demonstration of the category mistake is a highly illuminating solution to the mind-body problem. I also think that the Hard Problem of consciousness can be dissolved away by this method, but let's leave that discussion for another time. To wrestle with that long topic now would probably be a "blog category mistake"...