The poverty of the stimulus (POTS) argument is an argument in favour of linguistic nativism, which is the claim that humans are born with a specific adaptation for language that both funds and limits their competence to acquire specific types of natural languages over the course of their cognitive development and linguistic maturation. The basic idea informs the teachings of Socrates, Plato, and the Pythagoreans, pervades the work of the Cartesian linguists and Wilhelm von Humboldt, and surfaces again with the contemporary linguistic theories of Noam Chomsky. The argument is now generally used to support theories of generative grammar. The name was coined by Chomsky in his work Rules and Representations (Chomsky, 1980). The thesis emerged out of several of Chomsky's writings on the issue of language acquisition. The argument has been persuasive within linguistics, forming the empirical backbone for the theory of universal grammar. It is taught to students in most linguistics and psycholinguistics courses. Despite a large body of criticism it remains popular amongst linguists. Linguistics is the scientific study of human language, and someone who engages in this study is called a linguist. ... In the field of psychology, nativism is the view that certain skills or abilities are native or hard wired into the brain at birth. ... Linguistic competence refers to the knowledge of a language system. ... Linguistic typology is the typology that classifies languages by their features. ... The term natural language is used to distinguish languages spoken and signed (by hand signals and facial expressions) by humans for general-purpose communication from constructs such as writing, computer-programming languages or the languages used in the study of formal logic, especially mathematical logic. ... This article is about the ancient Greek philosopher. ... Plato ( Greek: Πλάτων, Plátōn, wide, broad-shouldered) (c. ... The Pythagoreans were an Hellenic organization of astronomers, musicians, mathematicians, and philosophers; who believed that all things are, essentially, numeric. ... // Cartesian Linguistics Introduction Noam Chomskys Cartesian Linguistics: A Chapter in the History of Rationalist Thought, published in 1966, has the purpose of deepening “our understanding of the nature of language and the mental processes and structures that underlies its use and acquisition” (ix). ... Wilhelm von Humboldt Friedrich Wilhelm Christian Karl Ferdinand Freiherr von Humboldt (June 22, 1767 - April 8, 1835), government functionary, foreign diplomat, philosopher, founder of Humboldt Universität in Berlin, friend of Goethe and especially of Schiller, is especially remembered as a German linguist who introduced a knowledge of the Basque... Noam Chomsky; photo credit: John Soares Avram Noam Chomsky (b. ... It has been suggested that this article or section be merged with Generative linguistics. ... This article or section contains information that has not been verified and thus might not be reliable. ... Universal grammar is a theory of linguistics postulating principles of grammar shared by all languages, thought to be innate to humans. ...

Summary of the argument

Though Chomsky reiterated the argument in a variety of different manners, one common structure to the argument can be summed up as follows:

1. There are patterns in all natural languages (i.e. human languages) that cannot be learned by children using positive evidence alone. Positive evidence is the set of grammatical sentences the language learner has access to, that is, by observing the speech of others. Negative evidence, on the other hand, is the evidence available to the language learner about what is not grammatical. For instance, when a parent corrects a child's speech, the child acquires negative evidence.
2. Children are only ever presented with positive evidence for these particular patterns, for example. they only hear others speaking using sentences that are "right", not those that are "wrong".
3. Children do learn the correct grammars for their native languages.

• Conclusion. Therefore, human beings must have some form of innate linguistic capacity which provides additional knowledge to language learners.

Evidence for the argument

The validity of the argument itself is unquestioned. Very few people, if any, would argue that Chomsky's conclusion doesn't follow from his premises. Thus, anyone who accepts the first three propositions must accept the conclusion. Many linguists accept all of the premises and consider there to be quite a bit of evidence for them. This article discusses validity in logic, for the term in the social sciences see validity (psychometric). ...

Several patterns in language have been claimed to be unlearnable from positive evidence alone. One example is the hierarchical nature of languages. The grammars of human languages produce hierarchichal tree structures and some linguists argue that human languages are also capable of infinite recursion (see Context-free grammar). For any given set of sentences generated by a hierarchichal grammar capable of infinite recursion there are an indefinite number of grammars which could have produced the same data. This would make learning any such language impossible. Indeed, a proof by E. Mark Gold showed that any formal language which has hierarchical structure capable of infinite recursion is unlearnable from positive evidence alone. (Of course, this is "unlearnable" in the sense that it is impossible to formulate a procedure which will discover with certainty the correct grammar. It may well be possible to arive at a good approximation of the correct grammar — or even the correct grammar itself — by a mixture of well-tuned heuristics, luck, etc.) Grammar is the study of rules governing the use of language. ... A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. ... The word infinity comes from the Latin infinitas or unboundedness. It refers to several distinct concepts which arise in theology, philosophy, mathematics and everyday life. ... A Sierpinski triangle —a confined recursion of triangles to form a geometric lattice. ... In linguistics and computer science, a context-free grammar (CFG) is a formal grammar in which every production rule is of the form V → w where V is a non-terminal symbol and w is a string consisting of terminals and/or non-terminals. ...

Another example of language pattern claimed to be unlearnable from positive evidence alone is subject-auxiliary inversion in questions, i.e.:

• You are happy.
• Are you happy?

There are two hypotheses the language learner might postulate about how to form questions: (1) The first auxiliary verb in the sentence (here 'are') moves to the beginning of the sentence, or (2) the 'main' auxiliary verb in the sentence moves to the front. In the sentence above, both rules yield the same result since there is only one auxiliary verb. But, you can see the difference in this case:

• Anyone who is interested can see me later.

1. Is anyone who interested can see me later?
2. Can anyone who is interested see me later?

Of course, the result of rule (1) is ungrammatical while the result of rule (2) is grammatical. So, rule (2) is (approximately) what we actually have in English, not rule (1). The claim, then, first is that children don't see sentences as complicated as this one enough to witness a case where the two hypotheses yield different results, and second that just based on the positive evidence of the simple sentences, children could not possibly decide between (1) and (2). Moreover, even sentences such as (1) and (2) are compatible with a number of incorrect rules (such as "front any auxiliary), as noted by Lasnik and Uriagereka (2002). Thus, if rule (2) was not innately known to infants, we would expect half of the adult population to use (1) and half to use (2). Since that doesn't occur, rule (2) must be innately known. (See Pullum 1996, linked below, for the complete account and critique.) Howard Lasnik is Professor of Linguistics at the University of Maryland. ...

The last premise, that children successfully learn language, is considered to be evident in human speech. Though people occasionally make mistakes, human beings rarely speak ungrammatical sentences, and generally do not label them as such when they say them. (Ungrammatical in the descriptive sense, not the prescriptive sense.) In linguistics, prescription is the laying down or prescribing of normative rules for a language. ... In linguistics, prescription is the laying down or prescribing of normative rules of the language. ...

That many linguists accept all four of the premises is testimony to Chomsky's influence in the discipline, and the persuasiveness of the argument. Nonetheless, the APS has many critics, both inside and outside linguistics.

Critiques of the argument

Though recognized as valid, the soundness of the poverty of stimulus argument is widely questioned. Indeed, every one of the three premises of the argument has been questioned at some point in time. A lot of the criticism comes from researchers who study language acquisition and computational linguistics. As well, connectionist researchers have never accepted most of Chomsky's premises, because they are at odds with connectionist beliefs about the structure of cognition. (This article discusses the soundess notion of informal logic. ... This article or section contains information that has not been verified and thus might not be reliable. ... Computational linguistics is an interdisciplinary field dealing with the statistical and logical modeling of natural language from a computational perspective. ... Connectionism is an approach in the fields of artificial intelligence, cognitive science, neuroscience, psychology and philosophy of mind. ...

The first and most common critique, is that positive evidence is actually enough to learn the various patterns which linguists claim are unlearnable by positive evidence alone. A common argument is that the brain's mechanisms of statistical pattern recognition could solve many of the imagined difficulties. For example, researchers using neural networks and other statistical methods have programmed computers to learn rules such as (2) cited above, and have successfully extracted hierarchical structures, all using positive evidence alone. (See Bates & Elman (1996), and Solan et al. (2005) below.) Some linguists remain skeptical as to whether these techniques will ever extract anything other than "toy" grammars. A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ... Pattern recognition is a field within the area of machine learning. ... Simplified view of an artificial neural network A neural network is an interconnected group of biological neurons. ... A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ...

As for the argument based on Gold's proof, it's not clear that human languages are truly capable of infinite recursion. After all, no one has ever witnessed a sentence infinitely long, and psycholinguistic experiments show that people find 4 or more layers of certain kinds of recursion quite confusing (though in some cases, such as "this is the cat that bit the rat that...", embedding does not inhibit processing). Chomsky and his supporters have long argued that these cases are best explained by restrictions on working memory, since this provides a principled explanation for limited recursion in language use. Some critics argue that this removes the falsifiability of the premise, rendering it unscientific. However, even amongst those who are skeptical about mentally represented recursive grammatical knowledge, it has quite generally been assumed that limits on embedding have something to do with "processing". Returning to the big picture, it is questionable whether Gold's research actually bears on question of natural language acquisition at all, since what Gold showed is that there are certain classes of formal languages for which some language in the class cannot be learned given positive evidence alone. It's not at all clear that natural languages fall in such a class, let alone whether they are the ones that are not learnable. (See Johnson 2004). Probably for these reasons, Chomsky himself has never advocated an argument based on Gold's proof. Psycholinguistics or Linguistics of psychology is the study of the psychological and neurological factors that enable humans to acquire, use and understand language. ... In cognitive psychology, working memory is the collection of structures and processes used for temporarily storing and manipulating information. ... This page discusses how a theory or assertion is falsifiable (disprovable opp: verifiable), rather than the non-philosophical use of falsification, meaning counterfeiting. ...

There is also criticism about whether negative evidence is really so rarely encountered by children. Pullum (1996) (linked below) argues that learners probably do get negative evidence of the rule. In addition, if one allows for statistical learning, negative evidence is abundant. Consider that if a language pattern is never encountered, but it's probability of being encountered would be very high were it true, then the language learner might be right in considering absence of the pattern as negative evidence. In Pullum and Scholz (2002) it has been also shown that examples of a number of puportedly rare constructions are reasonably common in available written corpora. Responses to the article have questioned the relevance of this result, given that children learn from spoken language. Pullum and Scholz respond that their corpus analysis is "preliminary", intended to serve as an impetus for further research, rather than a decisive refutation of any particular POS argument. In law a corpus (Latin: body) is a set, a collection of documents and sources. ...

Finally, it has been argued that people may not learn the exact same grammars as each other. If this is the case, then only a weak version of the third premise is true, as there would be no fully "correct" grammar to be learned. In many cases, POS arguments do not in fact depend on the assumption that there is only one correct grammar, but rather that there is only one correct class of grammars. For example, the POS argument from question formation only depends on the assumption that everyone learns a structure-dependent grammar.

References

• Bates, E. and Elman J. (1996). Learning Revisited. Science 274 (5294), 1849-1850.

• Chomsky, N. (1980). Rules and representations. Oxford: Basil Blackwell.

• Chomsky, N. (1988). Language and problems of knowledge. Cambridge, Massachusetts: MIT Press.

• Gold, E. (1967). Language identification in the limit. Information and Control 10, 447-474.

• Johnson, Kent. (2004). Gold's theorem and cognitive science. Philosophy of Science 71, 571-592.

• Marcus, Gary F. (1993). Negative evidence in language acquisition. Cognition 46 (1), 53-85.

• Pullum, Geoffrey K. (1996). Learnability, hyperlearning, and the poverty of the stimulus. In Proceedings of the 22nd Annual Meeting of the Berkely Linguistics Society: General Session and Parasession on the Role of Learnability in Grammatical Theory, ed. J. Johnson, M.L. Juge, and J.L. Moxley, 498-513. Berkeley, California. HTML

• Pullum, Geoffrey K., Scholz, Barbara C. (2002). Empirical assessment of stimulus poverty arguments. The Linguistic Review 19. 9–50. PDF

• Lasnik, Howard and Juan Uriagereka. (2002). On the Poverty of the Challenge. The Linguistic Review 19. 147-150. [1]

• Reich, P. (1969). The finiteness of natural language. Language 45, 831-843.

• Solan, Z., Horn, D., Ruppin, E., and Edelman, S. (2005). Unsupervised learning of natural languages. Proceedings of the National Academy of Sciences 102 (33), 11629-11634.

See also

To meet Wikipedias quality standards, this article or section may require cleanup. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Innatism is a philosophical doctrine introduced by Plato in the socratic dialogue Meno which holds that the mind is born with ideas/knowledge, and that therefore the mind is not a tabula rasa at birth. ... Nature versus nurture is a shorthand expression for debates about the relative importance of an individuals innate qualities (nature) versus personal experiences (nurture) in determining or causing individual differences in physical and behavioral traits. ... Government and binding is a theory of syntax in the tradition of transformational grammar developed by Noam Chomsky (1981, 1982, 1986). ... In the field of psychology, nativism is the view that certain skills or abilities are native or hard wired into the brain at birth. ... Rationalism, also known as the rationalist movement, is a philosophical doctrine that asserts that the truth can best be discovered by reason and factual analysis, rather than faith, dogma or religious teaching. ... Tabula rasa (Latin: scraped tablet, though often translated blank slate) is the notion that individual human beings are born blank (with no built-in mental content), and that their identity is defined entirely by their experiences and sensory perceptions of the outside world. ...

External links

• Essay supporting the poverty of stimulus argument
• Essay critiquing the poverty of stimulus argument
• Essay on Gold's proof, learnability and feedback