The innateness hypothesis is an expression coined by Hilary Putnam to refer to a linguistic theory of language acquisition which holds that at least some knowledge about language exists in humans at birth. Putnam used the expression "the innateness hypothesis" to target linguistic nativism and specifically the views of Noam Chomsky. Facts about the complexity of human language systems, the universality of language acquisition, the facility that children demonstrate in acquiring these systems, and the comparative performance of adults in attempting the same task are all commonly invoked in support. However, the validity of Chomsky's approach is still debated. Empiricists advocate that language is entirely learned. Some have criticized Chomsky's work, pinpointing problems with his theories while others have proposed new theories to account for language acquisition (with specific differences in terms of language acquisition per se compared to second language acquisition).
Linguistic nativism is the theory that humans are born with some knowledge of language. One acquires a language not entirely through learning.
Human language is complicated and is said to form one of the most complex areas of human cognition. However, despite its complexity, children are able to accurately acquire a language within a short period of time. Moreover, research has shown that language acquisition among children (including the blind and the deaf) occurs in ordered developmental stages. This highlights the possibility of humans having an innate language acquisition ability. According to Noam Chomsky, "The speed and precision of vocabulary acquisition leaves no real alternative to the conclusion that the child somehow has the concepts available before experience with language and is basically learning labels for concepts that are already a part of his or her conceptual apparatus." Chomsky's view that the human faculty of language is innate is also affirmed by Steven Pinker. Moreover, in his work, The Language Instinct, Pinker argued that language in humans is a biological adaptation—language is hard-wired into our minds by evolution. Furthermore, in contrast to children's ease in language acquisition, having passed the critical age for language acquisition the complexity of a language often makes it challenging for adult learners to pick up a second language. More often than not, unlike children, adults are unable to acquire native-like proficiency. Hence, with this idea in mind, nativists advocate that the fundamentals of language and grammar are innate rather than acquired through learning. The innateness hypothesis supports language nativism and several reasons and concepts have been proposed to support and explain this hypothesis. In his work, Chomsky introduced the idea of a language acquisition device (LAD) to account for the competence of humans in acquiring a language. The universal grammar (UG) that is also often credited to Chomsky was later introduced.
According to Chomsky, humans are born with a set of language learning tools referred to as the LAD. The LAD is an abstract part of the human mind which houses the ability for humans to acquire and produce language. Chomsky expressed that children are able to derive rules of a language through hypothesis testing because they are equipped with a LAD. The LAD then transforms these rules into basic grammar. Hence, according to Chomsky, the LAD explains why children seem to have the innate ability to acquire a language and accounts for why no explicit teaching is required for a child to acquire a language.
In his argument for the existence of a LAD, Chomsky proposed that for a child to acquire a language, sufficient innate language-specific knowledge is needed. These constraints were later termed as universal grammar (UG). In this theory, it is suggested that all humans have a set of limited rules for grammar that are universal to all natural human languages. These rules are genetically wired into our brains and they can be altered in correspondence to the language children are exposed to. In other words, under this theory, language acquisition is seen as a process of filtering through the set of possible grammatical structures in natural languages pre-programmed in one's mind and this is guided by the language input in one's environment. Chomsky later introduced generative grammar. He argued that "properties of a generative grammar arise from an "innate" universal grammar". This theory of generative grammar describes a set of rules that are used to order words correctly in order to form grammatically-sound sentences. It also attempts to describe a speaker's innate grammatical knowledge.
One of the most significant arguments generative grammarians had for language nativism is the poverty of the stimulus argument. Since 1980, the poverty of stimulus became increasingly integrated into the theory of generative grammar. In this argument, Noam Chomsky put forth that the amount of input a child receives during language acquisition is insufficient to account for the linguistic output. To be exact, he said that, "the native speaker has acquired a grammar on the basis of very restricted and degenerate evidence". Similarly, in his paper, Pinker concludes that humans have a system that is more sophisticated than what they are being exposed to.
In their article, Pullum and Scholz summarised the properties of a child's environment. They identified properties of positivity, degeneracy, incompleteness and idiosyncrasy. Under positivity, they assert that children are only exposed to positive linguistic data. Moreover, there is lack in negative data that aids a child in identifying ungrammatical sentences that are unacceptable in the language. It is also claimed that children are unable to acquire a language with positive evidence alone. In addition, under degeneracy, it is stated that children are often exposed to linguistic data that are erroneous. This is supported by Zohari that states that in adult speech, erroneous utterances that include speech slips, ungrammatical sentences, incomplete sentences etc. are often observed. Furthermore, the linguistic data each child is exposed to is different (i.e. idiosyncrasy) and there are many utterances that a child might not have heard (i.e. incompleteness). However, despite the properties mentioned above, children would eventually be able to deliver a linguistic output that is similar to the target language within a relatively short amount of time. In contrast, when placed in certain environments, other organisms are unable to attain the language mastery humans have reached. From the nativists' point of view, all of these highlight that babies are hard-wired with a UG and thus support the innateness hypothesis.
However, it is important to note that the argument that the poverty of stimulus supports the innateness hypothesis remains very controversial. For example, in one of the latest work against the poverty of stimulus argument, Fiona Cowie wrote in her paper that the Poverty of Stimulus argument fails "on both empirical and conceptual grounds to support nativism".
The critical period hypothesis by Linguist Eric Lenneberg states that full native competence in acquiring a language can only be achieved during an optimal period. This hypothesis supports the innateness hypothesis about the biological innateness of linguistic competence. Lenneberg expressed that age plays a salient role in the ability to acquire language. According to him, a child before the age of two will not sufficiently acquire language, while development of full native competence in a language must occur before the onset of puberty. This suggests that language is innate that occurs through development instead of feedback from the environment. As a result, should a child not hear any language during this period, the child would not be able to learn nor be able to speak. This hypothesis is also said to explain why adults do not acquire languages as well as children.
Evidence for the critical period hypothesis can be seen in the case of Genie. When discovered, she was without language. Genie's subsequent language acquisition process was studied, whereby her linguistic performance, cognitive and emotional development was deemed abnormal. Genie was said to have right-hemisphere language, resembling other cases where language was acquired outside of the "critical period". This would lend support to Lenneberg's hypothesis. Moreover, some saw the case of Genie as a support to the innateness hypothesis. When the LAD is not triggered during the critical period, the natural process of language acquisition cannot be reached. However, Genie's case is complex and controversial. It has been argued that it does not support linguistic innateness. Some have asserted that there is at least a possible degree of first language acquisition beyond the critical period. Moreover, the emotional and cognitive deprivation may have also played a part in Genie's linguistic and cognitive difficulties.
The development of the Nicaraguan sign language by students in a school for the deaf also lends evidence to the hypothesis. Initially a pidgin sign language with simple grammar, there were large grammatical differences and variations across signers. Eventually, the pidgin became a full-fledged language (like a creole) as younger signers developed a significantly more grammatically structured and regular system such as specific grammatical structures Often, the differences in abilities between the younger and older students to use sign language are said to suggest evidence for a critical period. The spontaneity of the development of NSL also shows that there is an innate element to the process of language learning.
Nonetheless, the critical period hypothesis in relation to language acquisition is also widely debated. Other research has also indicated that any age effects depend largely on the opportunities for learning, learning situations and how significant the initial exposure is.
Empiricism is the theory that all knowledge is based on experience derived from the senses. Empiricists only study observable behaviour instead of unobservable mental representations, states and processes. They claim that sense and experience is the ultimate source of all concepts and knowledge. On the other hand, linguistic empiricism is a perspective where language is entirely learned. These data-driven theorists also support that children do not have linguistically-specific knowledge at birth. Language and grammar are only learned through exposure and accumulated experience. This is also called the "nurture" perspective as opposed to the "nature" perspective (linguistic nativism).
Against Chomsky's Innateness Hypothesis, philosopher John Locke insisted that our knowledge, including language, cannot be innate. Instead, all ideas are derived from experience. Geoffrey Sampson also showed the same stand by stating that "Our languages are not inborn but are learned wholly with experience." Empiricists have criticised concepts like generative grammar that support linguistic nativism. In fact, some would argue that "language structure" is created through language use. Moreover, they assert that theories like the LAD are unsupported by empirical evidence.
Contrastive analyses about the innateness hypothesis have been done by Jacek Fisiak in 1980. According to Fisiak's analysis, Putnam, Hiż and Goodman criticized Chomsky's innate hypothesis by stating that:
It is hard to explain what it is for someone to have an innate concept since empirical evidence to support this theory is hard to find. In other words, there is no way to falsify the theory unless empirical evidence is found.
Over the years, many theories that are against language innateness have been developed to account for language acquisition. Many have championed that human beings learn language through experience with some leaning towards children being equipped with learning mechanisms while others suggesting that social situations or cognitive capacities can account for language learning.
Bates and Elman summarised a research conducted by Saffran, Aslin and Newport that supports that learning is "a purely inductive, statistically driven process". In the research, it was found that 8 month old infants were able to use simple statistics to identify word boundaries in speech. The results of the research highlight that language acquisition is a process of learning through statistical means. Moreover, it raises the possibility that infants possess experience-dependent mechanisms that allow for word segmentation and acquisition of other aspects of language. As a result, Bates and Elman found that this contradicts the extensive view that human beings are unable and cannot utilize generalized statistical procedures for language acquisition. This is empirical evidence for linguistic empiricism, thereby going against the innateness hypothesis.
Michael Tomasello's findings highlight the significance of a usage-based theory of language acquisition and indicates that there is a relation between cognitive and social skills with linguistic competence. This shows the importance of the role of experience in language acquisition. By empirically studying the developmental stages of child language acquisition, he argues that children have specific cognitive capacities at birth that promote growth in linguistic competence and specific interpersonal abilities that aid language learning. However, he emphasised that this does not prove that language is innate. In addition, his experiments indicate that children's awareness and understanding of the intentional communicative cues displayed by others is a salient social cognitive skill that determines their ability to learn words. Tomasello also stated that young children's initial multi-word productions are very concrete as they are based on specific words and phrases instead of innate and abstract linguistic categories. Hence, this would explain why grammar development is progressive and word-specific.
Geoffrey Sampson also supports that the "richness of the environment" plays a role in language acquisition. For example, Sampson observed that not only human beings but all species are capable of recognizing speech. This ability indicates that a child is equipped with the capacity for normalisation which plays a fundamental role in acquiring the phonology of a language. Therefore, he contends that a child is born with the ability to learn and this is through testing and guessing instead of the innate ability that nativists support.