With the aim of extending and updating Chomsky’s 1965 ‘Language Acquisition Device’ or LAD, Nunes (2002) postulated a function or device which evaluated the evidence of what the child heard, the ‘primary linguistic experience’, in relation to the possible variables, such as where the verb appears in the sentence, whether the subject is always pronounced, whether there are syllables without vowels as their heads, as there are in English little, and so on. In the framework here, these variables are known as ‘parameters’. By the proposal of Nunes (2002), this device was a critical genomic entity. By conceptual necessity, it had to be the last step in modern human evolution. Addressing the issue of multi-factoriality and co-morbidities in disorder, a small congenital defect in the specification of this device would be expected to have global effects. And as the last evolutionary step, this would be expected to be a relatively unstable aspect of modern human cognition. Learnability would be vulnerable and commonly compromised. Necessarily, for obvious biological reasons, this device had to be simple and easy to state. Crucially, such a device explained the finiteness of learnability, as manifest in the  fact that native speakers of English can agree that “The chicken is ready to eat is ambiguous,  while “The chicken is ready for eating” is not.

This was one of the first steps towards what is now known as ‘Biolinguistics’.

But the notion of a dedicated learnability device:

• Implicitly exaggerates the commonality between different instances of disorder,
• Makes it hard to explain the specificities of familial disorders across generations and family locales, other than by the interface with anatomical, neurological, and other physical strucrtures;
• Has little, if anything, to say about the highly uneven and asymmetric distribution of phonological ‘processes’, with, for instance, calculator as KALTALAYTA only occurring towards the end of the acquisition period and only in a small set of words, and working in the opposite polarity from doggie as GOGI (see Cruttenden (1978)) and magnet as MAGNIK.

In other words, the model is just wrong. In my opinion, there is a better account of the

• Multifactoriality, specificities, and asymmetries of disorder;
• And the finiteness of learnability;

by the more nuanced, albeit more complex, hypothesis here. This takes evolution to be a much more extended process than by the model of Robert Berwick and Noam Chomsky (2016). This goes beyond the proposals of Ljiljan Progovac (2015, 2019) and references therein.