The Faculty of Language: Narrow and Broad (FLN/FLB) Distinction

Origins of the Distinction

The distinction between the Faculty of Language in the Broad sense (FLB) and the Faculty of Language in the Narrow sense (FLN) was introduced by Marc Hauser, Noam Chomsky, and W. Tecumseh Fitch in their seminal 2002 paper, “The Faculty of Language: What Is It, Who Has It, and How Did It Evolve?” Published in Science, this paper sought to clarify the debate surrounding the evolution of language by proposing a specific framework for analyzing its constituent parts. Prior to this, discussions on language evolution often conflated various linguistic abilities, making it difficult to pinpoint which capacities were truly novel in humans and which had homologous or analogous counterparts in other species.

Hauser, Chomsky, and Fitch (2002) aimed to provide a more precise conceptual tool for researchers, arguing that a clearer definition of "language" was necessary to make progress in understanding its evolutionary trajectory. They posited that the human language faculty is not a monolithic entity but rather a complex system composed of multiple interacting components, some of which are shared with other animals and some of which are unique to humans.

The FLB and FLN Framework

The Faculty of Language in the Broad sense (FLB) encompasses all the sensory-motor, conceptual-intentional, and computational mechanisms that contribute to language. Crucially, FLB includes capacities that are shared with other animals, such as general cognitive abilities like memory, attention, and categorization, as well as specific sensory-motor systems involved in speech production and perception. For example, the ability to learn and produce complex vocalizations, while highly developed in humans, has parallels in birdsong and cetacean communication. Similarly, mechanisms for associating sounds with meanings, or for understanding intentions, are observed in various non-human species.

In contrast, the Faculty of Language in the Narrow sense (FLN) is defined as the abstract computational system that is unique to humans and is responsible for recursion. Recursion, in this context, refers to the ability to generate an infinite range of expressions from a finite set of elements, by embedding structures within other structures (e.g., "John said that Mary believes that Peter thinks..."). Hauser, Chomsky, and Fitch (2002) argued that FLN is the only component of the language faculty that is truly unique to humans and that it constitutes the "core" of language. They suggested that while other species might possess elements of FLB, none demonstrate the recursive computational capacity characteristic of FLN.

This framework implies that the evolutionary emergence of language in humans might not have involved the de novo evolution of an entirely new set of cognitive abilities. Instead, it could have resulted from a relatively small, perhaps even single, evolutionary change—the development of recursion—which then integrated with pre-existing cognitive and sensory-motor systems shared with other animals. This perspective shifts the focus of evolutionary inquiry from a broad search for all language-related capacities to a more targeted investigation of the origins of recursion.

Responses and Critiques

The FLN/FLB distinction generated significant discussion and debate within linguistics, cognitive science, and evolutionary biology. Some researchers embraced the framework for its clarity and its potential to guide empirical research, particularly in comparative cognition. It encouraged detailed comparisons of cognitive abilities, such as numerical competence, spatial reasoning, and social intelligence, across species to determine which elements of FLB are truly shared and which are uniquely human specializations.

However, the distinction also faced substantial criticism. One major point of contention revolved around the claim that recursion is the only unique component of human language (Jackendoff & Pinker, 2005). Critics argued that other aspects of language, such as complex compositional semantics (the ability to combine meanings systematically) or the human capacity for theory of mind (understanding others' intentions and beliefs), might also be uniquely human and integral to language, yet are not adequately captured by the narrow definition of FLN as solely recursion. For instance, Pinker and Jackendoff (2005) suggested that the FLN might be too restrictive and overlooks other critical adaptations for language, such as the mechanisms for mapping sounds to meanings and for organizing words into phrases.

Another line of critique questioned the empirical evidence for recursion being exclusively human (Everett, 2005). Some researchers have pointed to potential recursive-like structures in other domains of animal cognition, such as navigation or social hierarchies, or argued that the absence of observed recursion in animal communication does not definitively prove its absence as a cognitive capacity. Furthermore, the very definition and measurement of recursion in non-human animals proved challenging, leading to ongoing debates about what constitutes evidence for or against it.

Others have argued that the emphasis on a single, core faculty (FLN) might oversimplify the complex, multi-component nature of language evolution. They propose that language likely arose from a gradual co-evolution of multiple cognitive and social capacities, rather than a single 'big bang' event centered around recursion (e.g., Deacon, 1997; Tomasello, 2008). These perspectives suggest that social learning, cultural transmission, and the development of complex intentional communication systems might be just as crucial as recursion in explaining the emergence of human language.

Open Questions

Despite the debates, the FLN/FLB distinction has undeniably shaped the discourse on language evolution. It continues to prompt research into:

• The nature of recursion: Is it a domain-general cognitive ability or a language-specific one? What are its neural underpinnings?
• Comparative cognition: Which cognitive capacities traditionally associated with language are present in other species, and in what forms? How do these capacities differ quantitatively and qualitatively from human abilities?
• The role of other unique human traits: Beyond recursion, what other cognitive or social adaptations were necessary for the emergence of full human language? This includes investigations into theory of mind, shared intentionality, and advanced vocal learning.
• The evolutionary timeline: Did FLN emerge suddenly or gradually? What selective pressures might have favored its development?

The FLN/FLB framework remains a significant reference point, providing a structured way to approach the complex question of how human language evolved, even as researchers continue to refine and challenge its specific claims.