I shifted to look at two macaws flying and squawking overhead. Then I looked back at the log. It was closer to us now. Strange, I thought, the log is floating toward the bank, perpendicular to the current.
Then as it got closer, I saw that it really was undulating. Suddenly it came straight toward my end of the boat. This was no log. This was the largest anaconda I had ever seen. Its head was larger than mine. Its body was much thicker than mine and over thirty feet long. It opened its mouth wide and swam toward me. I swerved sharply, throwing my family to the side hard, and I managed to hit the snake with the propeller of my 15-horsepower outboard motor as it dove under the boat.Thud. A solid hit. I thought I had hit it in the head, but I wasn’t sure.
The snake disappeared. Then a second later the entire snake’s body stood up out of the water, towering above the boat, but receding behind us as we pressed forward, at about ten miles per hour. I looked at the entire length of the snake’s whitish underbelly as it fell backward with a loud, large splash into the Madeira River.
I didn’t know anacondas could to that, I thought. That damned thing could have jumped in the boat with us!
I was just staring. Shannon looked up now from her comic and said “Wow!”
This experience of mistaken perception taught me what psychologists have long known: perception is learned. We perceive the world, both as theoreticians and as citizens of the universe, according to our experiences and expectations, not always, perhaps even never, according to how the world actually is.
As I became more fluent in Pirahã, I began to harbor a suspicion that the people were keeping their speech simple for my sake. When they spoke to me, the sentences seemed short, with only one verb each. So I decided that it would be worth listening more carefully to how they spoke to one another, rather than basing my conclusions on how they spoke to me. My best opportunity, I knew, would come from Báígipóhoái, Xahoábisi’s wife. Each morning she talked loudly, beginning around five o’clock, sitting up in her hut in the dark, with Xahoábisi getting the fire going strong, only a few feet from my bedroom. She spoke to the entire village about what she had dreamed. She asked people by name what they were going to do that day. She told men leaving in canoes what kind of fish to catch, where the best places to fish were, how foreigners could be best avoided, and on and on. She was the village crier and gossip rolled into one. She was enjoyable to listen to. There was a certain artistry to her discourse, with her deep voice, the range of intonation in her talk (from very low to very high and back down again), the stylistically different way she pronounced her words—as if breath were going into her lungs and mouth rather than coming out. If ever there was a speaker that was speaking Pirahã for Pirahãs and not for me, the linguist, Báígi was it. Important for me, as I recorded then transcribed her sentences, they were structured identically to the sentences spoken to me by Kóhoi and other teachers—just one verb each.
This was especially challenging, since in my analysis of Pirahã grammar, I tried hard to collect examples where one phrase or sentence occurred inside another, as any linguist would, since such structures are supposed to reveal the grammar better than the simple sentences I was collecting. I began by looking for sentences like The man who caught the fish is in the house, where a sentence-like relative clause (who caught the fish) occurs within a noun phrase (The man . . .), which occurs within another sentence (The man is in the house). At the time, I believed that relative clauses existed in all languages.
In trying to figure out whether or not Pirahã had relative clauses, I decided to ask Kóhoi one day to tellme if I was “talking pretty”when I said, “The man came into the house. He was tall.” These are two simple sentences. In English, though, we would prefer to put the second sentence inside the former, to get a relative clause—“The man who was tall came into the house.” When I asked the Pirahã men whether my speech was pretty or not, usually they would say yes, to avoid rudeness. But then, if I had in fact expressed myself poorly, they would repeat the sentence I had mangled back to me in correct Pirahã, without ever telling me I was wrong. I was therefore hoping when I asked this particular question that Kóhoi would utter a corrective sentence and say something like “The man who is tall came into the house.” But, no, Kóhoi just said I was speaking pretty and repeated the phrases after me just as I had said them originally, something that the Pirahãs rarely do if the grammar is incorrect.
I experimented with various sentences using several different Pirahã teachers. All would either answer that I was speaking pretty or say “Xaió!” (Correct!)
So in a draft section of my Pirahã grammar about relative clauses I wrote that there were none in the language. But then one day Kóhoi was making a fishing arrow and needed a nail for the tip.
He spoke to his son, Paitá: “Ko Paitá, tapoá xigaboopaáti. Xoogiai hi goo tapoá xoáboi. Xaisigíai” (Hey Paitá, bring back some nails. Dan bought those very nails. They are the same).
I heard this and it stopped me in my tracks. I realized that these phrases were functioning together like a single sentence with a relative clause and that they could even be translated as such a sentence in En glish, but that their form was significantly different. They were three separate sentences, not one sentence with another sentence inside of it as in English. This Pirahã construction therefore lacked a relative clause in the sense that linguists usually mean. Crucially, the last sentence, Xaisigíai (They are the same), equated the word nails from the first two sentences. In English we would say, “Bring back the nails that Dan bought” (I have italicized the relative clause portion). I was thus seeing the separate clauses interpreted together even though they were not part of the same sentence. So there was a way of producing something like a relative clause in meaning, even if there were no relative clauses proper.
A sentence to most linguists is the expression in words of a proposition, an unspoken unit of meaning that represents a single thought, such as I ate, John saw Bill, or a single state, such as The ball is red, I have a hammer, and so on. Most languages not only have simple sentences like these, though, but they also have a way of putting one sentence or one phrase inside of another. This matrioshka-doll characteristic is known as recursion by computer scientists, linguists, psychologists, and philosophers. This issue is currently setting linguistics, philosophy of language, anthropology, and psychology ablaze, in a debate on the potential significance of Pirahã’s grammar for the understanding of humans and their languages.
In this respect, the evidence I was collecting was beginning to build support for two ideas I later came to hold about Pirahã sentence structure. The first was that Pirahã sentences lacked recursion. The second idea was that recursion wasn’t all that important—apparently, whatever you could say with recursion in one language, you could say without it in another. Linguists have long believed, though not always using the same terminology, that recursion is very important in language. And so I knew that any evidence that Pirahã could bring to bear on the issue would be important.
Chomsky was one of the first to ask how humans could produce so many sentences, an unbounded number, with only finite brains. There must be some tool available to allow us to make, as the common linguistics saying goes, “infinite use of finite means” (though I don’t think any linguist could really provide a coherent story of what that expression really means in scientific terms). Chomsky claimed that the fundamental tool that underlies all of this creativity of human language is recursion.
Recursion has traditionally been defined as the ability to put one item inside another of the same type (for the more mathematically inclined, it is a function with a procedure or a subroutine whose implementation references itself). A visual form of recursion occurs when you hold a mirror up to a mirror and see an infinite regress of mirrors in the reflection. And an auditory form of recursion is feedback, the squeal from an amplifier picking up and continuing to amplify its own output over and over.
These are the standard definitions of re
cursion. In syntax, again, this would translate into putting one unit inside another unit of the same type. Take a phrase like John’s brother’s son, which contains the noun phrases John, his brother, and his son. And a sentence like I said that you are ugly contains the sentence you are ugly.
In 2002, in the journal Science, Marc Hauser, Noam Chomsky, and Tecumseh Fitch placed a great burden on recursion by labeling it the unique component of human language. They claimed that recursion is the key to the creativity of language, in that as a grammar possesses this formal device, it can produce an infinite number of sentences of unbounded length.
However, as word has reached the scientific world of my claim that Pirahã lacks recursion in the mathematical, matrioshka-doll sense, a curious thing has happened. The definition of recursion has changed among some followers of Chomsky. In a sense this is an example of something the philosopher Richmond Thomason used to say to people who changed their mind on some subjects: “If at first you don’t succeed, redefine success.”
The newest definition of recursion to emerge from Chomsky’s school makes recursion a form of compositionality. Simply put, it says that you can put parts together to make something new and you can do that endlessly. Under this novel notion of recursion, which is not accepted by any mathematical linguists or computer scientists that I know of, if I can put words together to form a sentence, that is recursion, and if I can put sentences together to form a story, that is recursion.
My own reaction to this is that it errs by conflating reasoning with language. People clearly can put sentences together and then interpret them as a whole story. But this is the same ability crime scene investigators use when they interpret apparently disparate bits of evidence and assemble them into a story of how the crime was committed. This is not language, it is reasoning. Yet the major appeal of Chomskyan theory for most scientists is that it has separated reasoning and language, and in particular that Chomsky has distinguished the structure of stories from the structure of sentences and phrases. He has claimed many times that stories and sentences are put together by very different principles. So failing to draw that distinction in this new notion of recursion is, ironically, inconsistent with Chomsky’s own theory but consistent with mine.
If I am right about Pirahã lacking recursion, Chomsky and other researchers have some head scratching to do. They need to suggest how a language without recursion can fit into a theory in which recursion is the crucial component of language.
One answer that Chomsky and others have given to my claim that Pirahã lacks recursion is that recursion is a tool that’s made available by the brain, but it doesn’t have to be used. But then that’s very difficult to reconcile with the idea that it’s an essential property of human language, because if recursion doesn’t have to appear in one given language, then, in principle, it doesn’t have to appear in any language. This places them in the unenviable position of claiming that the unique property of human language does not actually have to be found in any human language.
It is not that hard, really, to tell whether recursion does any work in figuring out the grammar of a specific language. Quite simply, the question is twofold. First, can the grammar you write without recursion handle the language you are studying more simply than a grammar with recursion? Second, what kinds of phrases would you expect to find if the grammar did in fact have recursion? A language without recursion will look different from a language that has recursion. The main way is that it will not have phrases inside other phrases. If you find a phrase within a phrase, the language has recursion, period. If you don’t, it might not, though more data will be needed. The first question, then, is whether there are phrases within phrases in Pirahã. The answer is that there are not, following the standard argumentation used in theoretical linguistics to establish this: it lacks the pitch marking, words, or sentence size of a language with recursion.
The grammars of the world’s languages employ various markers to indicate that a given structure is recursive, that is, that one phrase is inside another. Such marking is not required, but it is very common. Some of these markers are independent words. In English, we say things like I said that he was coming. In this sentence, the phrase he was coming is located inside the phrase I said . . . ; He was coming is the content of what was said. In English, that is a frequently used “complementizer” for marking recursion. If we look at the relative clause complex that Kóhoi gave me, we see three independent sentences, interpreted jointly, without a shred of evidence that one sentence is inside another.
Another common marker of recursion is intonation, the use of pitch to mark different meaning and structural relations between sentences and their parts. The verb phrases of main clauses, for example, often get a higher pitch in English than the verb phrases of subordinate clauses. For example, in the most common pronunciation of the sentence The man that you saw yesterday is here, is here gets a higher pitch than saw yesterday. This is because saw yesterday is the subordinate, or embedded verb, phrase and is here is the main verb phrase. But Robert Van Valin and I, in a three-year National Science Foundation project dedicated to the study of intonation and its relation to syntax in five Amazonian languages, found no evidence that Pirahã uses intonation as an alternative marker of recursion. Now, Pirahã intonation does group sets of sentences together in paragraphs and stories, but this is not recursion in the grammar proper, at least not according to the entire history of Chomskyan grammar (though many linguists disagree with Chomsky and do place stories in the grammar—I have no quarrel at all with these other schools of linguistics in this sense). It is recursion in reasoning. In fact, many specialists on the role of intonation in human speech believe that it would be naive to try to link intonation directly to the structure of sentences rather than to the meanings of sentences and how they are used in stories. If this is correct, then intonation has nothing conclusive to say about whether a language has recursion or not.
Confusing language and reasoning is something that we have already seen to be a serious mistake. It is easy to confuse the two because reasoning involves many of the cognitive operations that some linguists associate with language, including recursion. Herbert Simon’s classic 1962 article, “The Architecture of Complexity,” gives a fascinating example of recursion outside of language. Simon’s example even shows how recursion can help your business! His example is worth citing in full:
There once was [sic] two watchmakers, named Hora and Tempus, who manufactured very fine watches. Both of them were highly regarded, and the phones in their workshops rang frequently. New customers were constantly calling them. However, Hora prospered while Tempus became poorer and poorer and finally lost his shop. What was the reason?
The watches the men made consisted of about 1,000 parts each. Tempus had so constructed his that if he had one partially assembled and had to put it down—to answer the phone, say—it immediately fell to pieces and had to be reassembled from the elements. The better the customers liked his watches the more they phoned him and the more difficult it became for him to find enough uninterrupted time to finish a watch.
The watches Hora handled were no less complex than those of Tempus, but he had designed them so that he could put together subassemblies of about ten elements each. Ten of these subassemblies, again, could be put together into a larger subassembly and a system of ten of the latter constituted the whole watch. Hence, when Hora had to put down a partly assembled watch in order to answer the phone, he lost only a small part of his work, and he assembled his watches in only a fraction of the man-hours it took Tempus.
This watchmaking example has nothing to do with language. So by this example, and many others, we know that human reasoning is recursive. In fact we know that many things in the world apart from humans are recursive (even atoms manifest recursivelike hierarchies in their construction from subatomic particles). Familiar Russian matrioshka dolls illustrate another type of recursion, known as nesting, where one doll is placed inside another of the same typ
e, and that pair into another of the same type, and so on.
An important inference from the presence of recursion is this: if a language has recursion then there should be no longest sentence in the language. For example, in English any sentence that someone utters can be made longer. The cat that ate the rat is well can be extended to The cat that ate the rat that ate the cheese is well, and so on.
Crucially, none of these diverse types of evidence for recursion is found in Pirahã. The story about the panther that Kaaboogí told me is typical. No evidence along any of these dimensions is found in that or other Pirahã texts for recursion in the grammar.
Most interesting, perhaps, for illustrating my point against recursion, is a sentence like the following, because there is no obvious way to make it longer in Pirahã: Xahoapióxio xigihí toioxaagá hi kabatií xogií xi mahaháíhiigí xiboítopí piohoaó, hoíhio (Another day an old man slowly butchered big tapirs by the side of the water, two of them). Anything else added to this, like the word brown in big brown tapirs, would render the sentence ungrammatical. Phrases can have a single modifier (phrases that are found in natural stories—I do have some artificial examples where I was able to get some Pirahãs to place more modifiers in the phrase, but they didn’t like it and never use more than one in a phrase in natural stories). A second one can occasionally be inserted at the end of the sentence as an afterthought—like the two of them at the end of this sentence. If this is correct, then Pirahã is finite and cannot be recursive.
I should rule out one final bit of potential evidence for recursion in Pirahã that has been suggested to me by several linguists. The first linguist to do so was Professor Ian Roberts, the head of linguistics at Cambridge University, during a debate with me on the BBC’s radio program Material World. He claimed that Pirahã must have recursion if it can add or repeat words or phrases after sentences, because, as he put it, “Iteration is a form of recursion.” Logically this is correct. Putting one phrase inside another at the end of a sentence is mathematically identical to repeating elements after a phrase or sentence. If I say, “John says that he is coming,” the sentence that he is coming is placed inside the sentence John says . . . at the end. This is known as “tail recursion.”Mathematically or logically this is equivalent to saying, “John runs, he does,” where the sentence he does is just a sentence repeated after another sentence. Pirahã can, indeed must, have one sentence follow another sentence, as in “Kóxoí soxóá kahapii. Hi xaoxai hiaba” (Kóxoí already left. He is not here). But if mere repetition, iteration, of one sentence after another satisfies Hauser, Chomsky, and Fitch’s definition of recursion (as some of their followers tell me it would), then it is found in species other than Homo sapiens.
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