字幕表 動画を再生する 英語字幕をプリント My name is Steve Pinker, and I’m Professor of Psychology at Harvard University. And today I’m going to speak to you about language. I’m actually not a linguist, but a cognitive scientist. I’m not so much interested as language as an object in its own right, but as a window to the human mind. Language is one of the fundamental topics in the human sciences. It’s the trait that most conspicuously distinguishes humans from other species, it’s essential to human cooperation; we accomplish amazing things by sharing our knowledge or coordinating our actions by means of words. It poses profound scientific mysteries such as, how did language evolve in this particular species? How does the brain compute language? But also, language has many practical applications not surprisingly given how central it is to human life. Language comes so naturally to us that we’re apt to forget what a strange and miraculous gift it is. But think about what you’re doing for the next hour. You’re going to be listening patiently as a guy makes noise as he exhales. Now, why would you do something like that? It’s not that I can claim that the sounds I’m going to make are particularly mellifluous, but rather I’ve coded information into the exact sequences of hisses and hums and squeaks and pops that I’ll be making. You have the ability to recover the information from that stream of noises allowing us to share ideas. Now, the ideas we are going to share are about this talent, language, but with a slightly different sequence of hisses and squeaks, I could cause you to be thinking thoughts about a vast array of topics, anything from the latest developments in your favorite reality show to theories of the origin of the universe. This is what I think of as the miracle of language, its vast expressive power, and it’s a phenomenon that still fills me with wonder, even after having studied language for 35 years. And it is the prime phenomenon that the science of language aims to explain. Not surprisingly, language is central to human life. The Biblical story of the Tower of Babel reminds us that humans accomplish great things because they can exchange information about their knowledge and intentions via the medium of language. Language, moreover, is not a peculiarity of one culture, but it has been found in every society ever studied by anthropologists. There’s some 6,000 languages spoken on Earth, all of them complex, and no one has ever discovered a human society that lacks complex language. For this and other reasons, Charles Darwin wrote, “Man has an instinctive tendency to speak as we see in the babble of our young children while no child has an instinctive tendency to bake, brew or write.” Language is an intricate talent and it’s not surprising that the science of language should be a complex discipline. It includes the study of how language itself works including: grammar, the assembly of words, phrases and sentences; phonology, the study of sound; semantics, the study of meaning; and pragmatics, the study of the use of language in conversation. Scientists interested in language also study how it is processed in real time, a field called psycholinguistics; how is it acquired by children, the study of language acquisition. And how it is computed in the brain, the discipline called neurolinguistics. Now, before we begin, it’s important to not to confuse language with three other things that are closely related to language. One of them is written language. Unlike spoken language, which is found in all human cultures throughout history, writing was invented a very small number of times in human history, about 5,000 years ago. And alphabetic writing where each mark on the page stands for a vowel or a consonant, appears to have been invented only once in all of human history by the Canaanites about 3,700 years ago. And as Darwin pointed out, children have no instinctive tendency to write, but have to learn it through construction and schooling. A second thing not to confuse language with is proper grammar. Linguists distinguish between descriptive grammar - the rules, that characterize how people to speak - and prescriptive grammar - rules that characterize how people ought to speak if they are writing careful written prose. A dirty secret from linguistics is that not only are these not the same kinds of rules, but many of the prescriptive rules of language make no sense whatsoever. Take one of the most famous of these rules, the rule not to split infinitives. According to this rule, Captain Kirk made a grievous grammatical error when he said that the mission of the Enterprise was “to boldly go where no man has gone before.” He should have said, according to these editors, “to go boldly where no man has gone before,” which immediately clashes with the rhythm and structure of ordinary English. In fact, this prescriptive rule was based on a clumsy analogy with Latin where you can’t splint an infinitive because it’s a single word, as in facary[ph] to do. Julius Caesar couldn’t have split an infinitive if he wanted to. That rule was translated literally over into English where it really should not apply. Another famous prescriptive rule is that, one should never use a so-called double negative. Mick Jagger should not have sung, “I can’t get no satisfaction,” he really should have sung, “I can’t get any satisfaction.” Now, this is often promoted as a rule of logical speaking, but “can’t” and “any” is just as much of a double negative as “can’t” and “no.” The only reason that “can’t get any satisfaction” is deemed correct and “can’t get no satisfaction” is deemed ungrammatical is that the dialect of English spoken in the south of England in the 17th century used “can’t” “any” rather than “can’t” “no.” If the capital of England had been in the north of the country instead of the south of the country, then “can’t get no,” would have been correct and “can’t get any,” would have been deemed incorrect. There’s nothing special about a language that happens to be chosen as the standard for a given country. In fact, if you compare the rules of languages and so-called dialects, each one is complex in different ways. Take for example, African-American vernacular English, also called Black English or Ebonics. There is a construction in African-American where you can say, “He be workin,” which is not an error or bastardization or a corruption of Standard English, but in fact conveys a subtle distinction, one that’s different than simply, “He workin.” “He be workin,” means that he is employed; he has a job, “He workin,” means that he happens to be working at the moment that you and I are speaking. Now, this is a tense difference that can be made in African-American English that is not made in Standard English, one of many examples in which the dialects have their own set of rules that is just as sophisticated and complex as the one in the standard language. Now, a third thing, not to confuse language with is thought. Many people report that they think in language, but commune of psychologists have shown that there are many kinds of thought that don’t actually take place in the form of sentences. (1.) Babies (and other mammals) communicate without speech For example, we know from ingenious experiments that non-linguistic creatures, such as babies before they’ve learned to speak, or other kinds of animals, have sophisticated kinds of cognition, they register cause and effect and objects and the intentions of other people, all without the benefit of speech. (2.) Types of thinking go on without language--visual thinking We also know that even in creatures that do have language, namely adults, a lot of thinking goes on in forms other than language, for example, visual imagery. If you look at the top two three-dimensional figures in this display, and I would ask you, do they have the same shape or a different shape? People don’t solve that problem by describing those strings of cubes in words, but rather by taking an image of one and mentally rotating it into the orientation of the other, a form of non-linguistic thinking. (3.) We use tacit knowledge to understand language and remember the gist For that matter, even when you understand language, what you come away with is not in itself the actual language that you hear. Another important finding in cognitive psychology is that long-term memory for verbal material records the gist or the meaning or the content of the words rather than the exact form of the words. For example, I like to think that you retain some memory of what I have been saying for the last 10 minutes. But I suspect that if I were to ask you to reproduce any sentence that I have uttered, you would be incapable of doing so. What sticks in memory is far more abstract than the actual sentences, something that we can call meaning or content or semantics. In fact, when it even comes to understanding a sentence, the actual words are the tip of a vast iceberg of a very rapid, unconscious, non-linguistic processing that’s necessary even to make sense of the language itself. And I’ll illustrate this with a classic bit of poetry, the lines from the shampoo bottle. “Wet hair, lather, rinse, repeat.” Now, in understanding that very simple snatch of language, you have to know, for example, that when you repeat, you don’t wet your hair a second time because its already wet, and when you get to the end of it and you see “repeat,” you don’t keep repeating over and over in infinite loop, repeat here means, “repeat just once.” Now this tacit knowledge of what the writers **** of language had in mind is necessary to understand language, but it, itself, is not language. (4.) If language is thinking, then where did it come from? Finally, if language were really thought, it would raise the question of where language would come from if it were incapable of thinking without language. After all, the English language was not designed by some committee of Martians who came down to Earth and gave it to us. Rather, language is a grassroots phenomenon. It’s the original wiki, which aggregates the contributions of hundreds of thousands of people who invent jargon and slang and new constructions, some of them get accumulated into the language as people seek out new ways of expressing their thoughts, and that’s how we get a language in the first place. Now, this not to deny that language can affect thought and linguistics has long been interested in what has sometimes been called, the linguistic relativity hypothesis or the Sapir-Whorf Hypothesis (note correct spelling, named after the two linguists who first formulated it, namely that language can affect thought. There’s a lot of controversy over the status of the linguistic relativity hypothesis, but no one believes that language is the same thing as thought and that all of our mental life consists of reciting sentences. Now that we have set aside what language is not, let’s turn to what language is beginning with the question of how language works. In a nutshell, you can divide language into three topics. There are the words that are the basic components of sentences that are stored in a part of long-term memory that we can call the mental lexicon or the mental dictionary. There are rules, the recipes or algorithms that we use to assemble bits of language into more complex stretches of language including syntax, the rules that allow us to assemble words into phrases and sentences; Morphology, the rules that allow us to assemble bits of words, like prefixes and suffixes into complex words; Phonology, the rules that allow us to combine vowels and consonants into the smallest words. And then all of this knowledge of language has to connect to the world through interfaces that allow us to understand language coming from others to produce language that others can understand us, the language interfaces. Let’s start with words. The basic principle of a word was identified by the Swiss linguist, Ferdinand de Saussure, more than 100 years ago when he called attention to the arbitrariness of the sign. Take for example the word, “duck.” The word, “duck” doesn’t look like a duck or walk like a duck or quack like a duck, but I can use it to get you to think the thought of a duck because all of us at some point in our lives have memorized that brute force association between that sound and that meaning, which means that it has to be stored in memory in some format, in a very simplified form and an entry in the mental lexicon might look something like this. There is a symbol for the word itself, there is some kind of specification of its sound and there’s some kind of specification of its meaning. Now, one of the remarkable facts about the mental lexicon is how capacious it is. Using dictionary sampling techniques where you say, take the top left-hand word on every 20th page of the dictionary, give it to people in a multiple choice test, correct for guessing, and multiply by the size of the dictionary, you can estimate that a typical high school graduate has a vocabulary of around 60,000 words, which works out to a rate of learning of about one new word every two hours starting from the age of one. When you think that every one of these words is arbitrary as a telephone number of a date in history, you’re reminded about the remarkable capacity of human long-term memory to store the meanings and sounds of words. But of course, we don’t just blurt out individual words, we combine them into phrases and sentences. And that brings up the second major component of language; namely, grammar. Now the modern study of grammar is inseparable to the contributions of one linguist, the famous scholar, Noam Chomsky, who set the agenda for the field of linguistics for the last 60 years. To begin with, Chomsky noted that the main puzzle that we have to explain in understanding language is creativity or as linguists often call it productivity, the ability to produce and understand new sentences. Except for a small number of clichéd formulas, just about any sentence that you produce or understand is a brand new combination produced for the first time perhaps in your life, perhaps even in the history of the species. We have to explain how people are capable of doing it. It shows that when we know a language, we haven’t just memorized a very long list of sentences, but rather have internalized a grammar or algorithm or recipe for combining elements into brand new assemblies. For that reason, Chomsky has insisted that linguistics is really properly a branch of psychology and is a window into the human mind. A second insight is that languages have a syntax which can’t be identified with their meaning. Now, the only quotation that I know of, of a linguist that has actually made it into Bartlett’s Familiar Quotations, is the following sentence from Chomsky, from 1956, “Colorless, green ideas sleep furiously.” Well, what’s the point of that sentence? The point is that it is very close to meaningless. On the other hand, any English speaker can instantly recognize that it conforms to the patterns of English syntax. Compare, for example, “furiously sleep ideas dream colorless,” which is also meaningless, but we perceive as a word salad. A third insight is that syntax doesn’t consist of a string of word by word associations as in stimulus response theories in psychology where producing a word is a response which you then hear and it becomes a stimulus to producing the next word, and so on. Again, the sentence, “colorless green ideas sleep furiously,” can help make this point. Because if you look at the word by word transition probabilities in that sentence, for example, colorless and then green; how often have you heard colorless and green in succession. Probably zero times. Green and ideas, those two words never occur together, ideas and sleep, sleep and furiously. Every one of the transition probabilities is very close to zero, nonetheless, the sentence as a whole can be perceived as a well-formed English sentence. Language in general has long distance dependencies. The word in one position in a sentence can dictate the choice of the word several positions downstream. For example, if you begin a sentence with “either,” somewhere down the line, there has to be an “or.” If you have an “if,” generally, you expect somewhere down the line there to be a “then.” There’s a story about a child who says to his father, “Daddy, why did you bring that book that I don’t want to be read to out of, up for?” Where you have a set of nested or embedded long distance dependencies. Indeed, one of the applications of linguistics to the study of good prose style is that sentences can be rendered difficult to understand if they have too many long distance dependencies because that could put a strain on the short-term memory of the reader or listener while trying to understand them. Rather than a set of word by word associations, sentences are assembled in a hierarchical structure that looks like an upside down tree. Let me give you an example of how that works in the case of English. One of the basic rules of English is that a sentence consists of a noun phrase, the subject, followed by a verb phrase, the predicate. A second rule in turn expands the verb phrase. A very phrase consists of a verb followed by a noun phrase, the object, followed by a sentence, the complement as, “I told him that it was sunny outside.” Now, why do linguists insist that language must be composed out of phrase structural rules? (1.) Rules allow for open-ended creativity Well for one thing, that helps explain the main phenomenon that we want to explain, mainly the open-ended creativity of language. (2.) Rules allow for expression of unfamiliar meaning It allows us to express unfamiliar meanings. There’s a cliché in journalism for example, that when a dog bites a man, that isn’t news, but when a man bites a dog, that is news. The beauty of grammar is that it allows us to convey news by assembling into familiar word in brand new combinations. Also, because of the way phrase structure rules work, they produce a vast number of possible combinations.