Steven Pinker -- How the Mind Works - Hampshire High Italian ...

122 I HOW THE MIND WORKSroles. The bottom of page 121 shows, in simplified form, a model devisedby Geoffrey Hinton that does handle the sentences.The bank of "proposition" units light up in arbitrary patterns, a bit likeserial numbers, that label complete thoughts. It acts as a superstructurekeeping the concepts in each proposition in their proper slots. Note howclosely the architecture of the network implements standard, languagelikementalese! There have been other suggestions for compositional networksthat aren't such obvious mimics, but they all have to have somespecially engineered parts that separate concepts from their roles andthat bind each concept to its role properly. The ingredients of logic suchas predicate, argument, and proposition, and the computational machineryto handle them, have to be snuck back in to get a model to do mindlikethings; association-stuff by itself is not enough.Another mental talent that you may never have realized you have is calledquantification, or variable-binding. It arises from a combination of the firstproblem, individuals, with the second, compositionality. Our compositionalthoughts are, after all, often about individuals, and it makes a differencehow those individuals are linked to the various parts of the thought. Thethought that a particular baby ate a particular slug is different from thethought that a particular baby eats slugs in general, or that babies in generaleat slugs in general. There is a family of jokes whose humor depends on thelistener appreciating that difference. "Every forty-five seconds someone inthe United States sustains a head injury." "Omigod! That poor guy!" Whenwe hear that "Hildegard wants to marry a man with big musclesj" we wonderwhether she has a particular he-man lined up or if she is just hanginghopefully around the gym. Abraham Lincoln said, "You may fool all the peoplesome of the time; you can even fool some of the people all the time; butyou can't fool all of the people all the time." Without an ability to computequantification, we could not understand what he said.In these examples, we have several sentences, or several readings ofan ambiguous sentence, in which the same concepts play the same rolesbut the ideas as a whole are very different. Hooking up concepts to theirroles is not enough. Logicians capture these distinctions with variablesand quantifiers. A variable is a place-holding symbol like x or y whichstands for the same entity across different propositions or different parts