The process of learning to talk is a journey of a special sort – with a rather subtly defined end-point – being able to agree about what things mean. People brought up in an English-speaking environment mostly end up agreeing that:

• There is no difference in meaning between “You believe that it’s true?” and “You believe it’s true?”
• “The rabbit is ready to eat” means two things, one good for the rabbit, one not.
• “Mightn’t the ball that won the match that the bookie keeps talking about have been being examined by the umpire?” is meaningful (even if it clunks more than somewhat).

For any language, agreement on such points is possible in principle.  Some children will hear examples of at least the separate elements of all of the necessary contrasts. But others may not. Hence the logical problem of language acquisition. So the expectation is problematic. How is there a meeting of minds? How does the agreement happen?

Although development does not recapitulate evolution, there is often a relation. And in this case I propose, on acquisition evidence, that there is a strong relation, that the progress towards agreement can only be based on a particular sequence in the evolution of speech and language, and that the core of the essential apparatus for speech and language. known as Universal Grammar, is known by most children by the age of three. But as Carol Chomsky (1969) showed, there are subtle aspects of the grammar which are still normally in process at eight, not finally mastered until ten, and sometimes not mastered at all. Nunes (2002) shows that for most children, the final stages of speech acquisition are still in process at eight. And Nunes (2022) confirms Carol Chomsky’s result with observational diary data, construed in a current theoretical framework.

In all cultures, this seemingly extraordinary feat of acquisition is accomplished effortlessly and reliably over this approximate time scale of around ten years. By the mental structure which makes this possible, human beings are different from any other animal.

First, during the second half of the first year, the child babbles, rehearsing the forms of speech and language with no detectable meanings or intentions. Then the child starts producing what Martin Braine (1962) called ‘holophrases’ – expressions which sound like they might contain more than one word – but not occurring on their own – like OZAH, as an expression of apparent curiosity, possibly modeled on “What’s that?”. Then gradually the elements become more distinct, as in “Mummy bye” or “Daddy bye”, with no clear structural relation between the elements, Then, typically sometime between 18 and 21 months, elements more recognisable as words start to be put together. The child says something like “MM BAH” as he or she is being put into the bath, with two contrasting elements relating to a significant entity in the child’s universe, in this case bath, and a plausible version of the preposition in, in a primitive prototype of a phrase. Then between a week and three months after saying something like “In bath” most naturally interpreted as a simple ‘declarative’, as such structures are known, the child either asks a question like “Where Daddy?” or answers a fully formed corresponding question by an adult like “Where’s Daddy?” by an appropriate and plausible reference to place, possibly by a single word. But not in the opposite order. In other words, two word declaratives precede one word answers to questions, even though the one word answer might seem simpler. This is the lowermost point which can be characterised in terms of the sort of relation, outlined by the Framework here. From this point, acquisition can be plotted by an eight-step path towards the essentials of the end-state. But there is no schedule, other than a very approximate one. Each child has his or her own ideas about this.