"In the famous Chinese Room thought experiment, a non-Chinese-speaking person sits in a room furnished with many rulebooks. Taken together, these rulebooks perfectly specify how to take any incoming sequence of Chinese symbols and craft an appropriate response. A person outside slips questions written in Chinese under the door. The person inside consults the rulebooks, then sends back perfectly coherent answers in Chinese.
The thought experiment has been used to argue that, no matter how it might appear from the outside, the person inside the room can’t be said to have any true understanding of Chinese. Still, even a simulacrum of understanding has been a good enough goal for natural language processing.
The only problem is that perfect rulebooks don’t exist, because natural language is far too complex and haphazard to be reduced to a rigid set of specifications. Take syntax, for example: the rules (and rules of thumb) that define how words group into meaningful sentences. The phrase “colorless green ideas sleep furiously” has perfect syntax, but any natural speaker knows it’s nonsense. What prewritten rulebook could capture this “unwritten” fact about natural language — or innumerable others?"