In this light, a conclusion in the Guidebook for Bilingual Parents can be confirmed:
First and second language acquisition differ substantially, probably due to age-related changes of acquisition capacities … Although acquisition remains possible at all ages, some acquisition mechanisms become inaccessible in successive acquisition. Learners intuitively resort to others to replace them (Meisel: 200f).
Even if, like in this conclusion, certain principles of a UG are assumed to exist in some acquisition mechanisms, they might depend on other, external properties such as motivation, focus on study, communicative skills, cultural and age-related influences. Thus, it might yet be possible to reconcile nativist with nurture positions. Taking UG as a biological feature, it seems to be an “endowment” for language acquisition following certain phases in a child’s linguistic development—up to the age of four to five years. L2 principles, on the other hand, point at the abovementioned differences for older language learners. The solution might be to look at the transition from domain-specific mechanisms (nature) to domain-general modules (nurture) that allow for more conscious, effective and time-saving language studies, a quality especially important for CLIL and immersion programs. This transition would be in accordance with constructivist learning theories, observations from the concept of Visible Learning and not least from neurocognitive research, which testifies remarkable plasticity in the cognitive system throughout people’s lives.
Robert Vroman’s FDH tries to account for general characteristics of foreign language learning and his theory can consistently be connected with post-puberty learners, such as in most CLIL strands in schools. L2 acquisition in a classroom setting would resemble the process of general “adult” learning where there is no domain-specific module believed to exist and issues are the role of input, grammatical structures and the transfer of lexical categories. This is particularly important in CLIL programs where the transfer from subject-related concepts from L2 to L1 is one of the guiding learning objectives. Content-based teaching and learning demonstrates that processes of the language faculty—as in UG—are not exclusive to language and that “both native and subsequent languages draw on similar resources in acquisition and processing” (Herschensohn: 260). The “endowment” of the mental module or faculty in language acquisition allegedly declines with age in order to free up neural resources for other operations. Adolescents in CLIL settings would begin to rely instead on problem-solving skills to understand and handle content and consciously acquire L2 lexis and grammatical structures.
3.2 Linking Nature and Nurture
In effect, Vroman’s FDH was able to create a link between the nativist (UG-) position in primary language acquisition and the idea that L2 learning was predominantly influenced by external factors and “nurtured” by educational and societal settings rather than by an innate language “endowment”. This, however, does not completely answer the question how children and adolescents learn to develop their language(s), which boils down to the controversy whether language acquisition is enabled by this “endowment”, the language acquisition faculty, or a result of environmental influences—in other words facilitated by nature or nurture.
According to Chomsky, language acquisition has a biological foundation which would be backed up by the following considerations: sounds are acquired in a certain sequence and are common to all world languages. The Guidebook for Bilingual Parents documents identical developmental phases for all children from the discrimination of sounds, a focus on language properties, different reactions to function and property words and—after two years—a rapid increase in the number of lexical items acquired (Meisel: 37 ff). These processes would occur in all world languages and confirm the existence of an innate mental structure, the domain-specific mechanism of UG.
In contrast to that, behaviorist theory had proposed that a child’s environment was the most important factor in language learning and would include, even be based on imitation, a clear-cut nurture position. Whereas imitation certainly plays a limited role even in second language acquisition, learners do not imitate everything they hear and are selective in what they produce; this could be taken as a hint at an “internal language-monitoring process” (Lanir 2019: n.p.) rather than the nurture aspect of environmental conditioning. Further aspects that cannot be explained by the process of imitation are overgeneralizations like goed, putted, mouses and sheeps (in inflection) and non-existent language structures that children never heard. Language chunks acquired through imitation become locked in a child’s memory and are not assimilated in their language production and thus dysfunctional. At the same time, children produce many more sounds and combinations than they hear and understand much more than they can produce—this phenomenon is also known as Poverty of Stimulus (POS—cf. Riemer: 277). Overall, they are exposed to language performance instead of competence and can even extract linguistic rules from incomplete or faulty language they listen to (cf. ibid.).
These aspects come across as a critical view of behaviorist language theory and an appreciation of the innate position of a UG and domain-specific mental modules. And indeed, despite all recent rejection of Chomsky’s propositions—including his own revocation of UG and resort to paradigms like recursion (cf. Everett 2017)—a study of psychologists claims to have found new support for Chomsky’s “internal grammar” theory:
One of the foundational elements of Chomsky’s work is that we have a grammar in our head, which underlies our processing of language,” explains David Poeppel, the study’s senior researcher and a professor in New York University’s Department of Psychology. “Our neurophysiological findings support this theory: we make sense of strings of words because our brains combine words into constituents in a hierarchical manner—a process that reflects an ‘internal grammar’ mechanism (NYU: 2015 n.p.).
On the other hand, and conceding that a universal grammar is not impossible in principle, linguists like Daniel Everett do not see much evidence for it and maintain that it would not work in any case. In his view, a complex interplay of factors structures the way humans talk and what they talk about. In that he is supported by developmental psychologists, and Michael Tomasello (2008), for instance, agrees that grammatical principles and constructions have no neural foundation but stem from more general cognitive processes and are part of communication in particular linguistic communities, although aspects of language competence might have evolved biologically. Everett, in his book Language: The Cultural Tool (2012), argues that the rules of language are “not innate but spring from necessity and circumstance”:
Language is possible due to a number of cognitive and physical characteristics that are unique to humans but none of which that are unique to language. Coming together they make language possible. But the fundamental building block of language is community. Humans are a social species more than any other, and in order to build a community, which for some reason humans have to do in order to live, we have to solve the communication problem. Language is the tool that was invented to solve that problem. … The lesson is that language is not something mysterious that is outside the bounds of natural selection, or just popped into being through some mutated gene. But that language is a human invention to solve a human problem. Other creatures can't use it for the same reason they can't use a shovel: it was invented by humans, for humans and its success is judged by humans (Everett: 2012 n.p.).
3.3 Anthropology Sheds a New Light
Beyond the linguistic nativist-versus-learning debate, related fields in psychology (Pinker) and literature (Caliban/Ortega) have quite intensely mirrored the nature-versus-nurture controversy, which has a long history reaching even back to the beginnings of anthropology (Boas) in the late 19th century. Building blocks of this controversy will be helpful to consider in some detail because an integrative CLIL methodology not only needs to connect language and content, but also has to specify the various aspect of subject matters to establish content, which in addition to natural and