The empirical record across independent disciplines confirms the structural prediction that any system carrying propositions must instantiate the same three structural features. Cross-linguistic typology finds the same structural skeleton across thousands of unrelated languages. Greenberg (1963) identified word-order universals that correlate with how languages mark argument structure. Comrie (1989) and Croft (2003) documented recurring patterns in how languages encode tense, aspect, modality, and grammatical relations. Where surface features vary — some languages are head-initial, others head-final; some mark case morphologically, others syntactically; some grammaticalize evidentiality, others handle it lexically — the deep structural features recur. The variation is on what structure already affords; structure itself is what makes the variation intelligible as variation within the same kind.

Non-human communicative systems instantiate the same three structural features on their own terms. The waggle dance of honeybees encodes spatial information (direction and distance to food) through a temporally ordered sequence of body movements that causally influences receiving bees who then fly along the encoded vector (Frisch 1967; Seeley 1995). Cetacean signature whistles identify individuals and coordinate group behavior across distances in a medium where vision is useless (Janik and Slater 1998; King and Janik 2013). Vervet monkeys use distinct alarm calls for distinct predators, and conspecifics respond with predator-appropriate behavior (Seyfarth, Cheney, and Marler 1980). In each case the system has distinguishable signs, temporal ordering, and causal transmission, because nothing else could do the coordinating work these species need done.

The Chomsky/Tomasello debate about whether grammatical constraints are innate or emergent from communicative practice (Chomsky 1965; Tomasello 2003; Goldberg 2006) is a live dispute about the proximate source of human linguistic universals. The structural account is neutral on it. Wherever the specific constraints originate, the deeper requirement is located in what any communicative system must be — distinguishable signs, sequential ordering, causal transmission. Whether human brains come pre-equipped with those requirements or discover them again each generation through use, they obtain either way.

A particularly sharp confirmation comes from spontaneous language genesis. When speakers without a shared language are thrown together, they generate pidgins, which their children convert into fully grammatical creoles (Bickerton 1981, 1984). Deaf children in Nicaragua, brought together in schools in the 1970s and 1980s without a pre-existing sign language, spontaneously generated Nicaraguan Sign Language — and the children generated a grammar more complex than their first teachers used (Kegl, Senghas, and Coppola 1999; Senghas, Kita, and Özyürek 2004). The grammatical features that emerged were not taught and not copied from any existing language. They emerged because anyone who needs to be understood by anyone else will, sooner or later, invent the features being understood requires — even when nothing outside them supplies those features. This is the structural answer to what linguists call the poverty-of-the-stimulus argument (the claim that children's linguistic input is too sparse to determine the grammar they end up with): the grammar children converge on is not being derived from insufficient input because it is not being derived at all — it is what propositional coordination structurally requires, and minds generate it whenever coordination is at stake.


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← [8.10.3 What is Predicted](<8.10.3 What is Predicted.md>) | [8.10.5 What is Concluded](<8.10.5 What is Concluded.md>) →
