The D-I-Y University: Week 3 Day 3 Language

Mel Brooks could just about accept that the adults he met in France could speak French - maybe they went to night classes or something - but how could the little kids do it too?

It's certainly not because they were born with the knowledge. Take a newborn French child to Mel Brooks' New York apartment and in a few years it might well be familiar with New York shtick, but it will know very little about cheeses, subjunctive variations for aller, or the proper lip formation to produce that one sound all English speakers dread, which on vacation we race through elaborate contortions to avoid: the feared past participle of "to have": eu.

Let the kid escape back to France though, and it'll end up speaking good French - albeit with a baffling insistence for le pastrami vous shmuck instead of Camembert - but even if you watch closely, even if you keep a video trained on it and transcribe every word it hears, you'll never find the moment when its parents sit it down and go through the Academie Francaise grammar books which explain, for every contingency, just where that English-humiliating eu is to be dropped in.

It's not just busy French parents. Children never get a full grammar explained to them. All they really hear are fragments: "Do this", "Try that". "Please don't dangle Mommy's computer outside the window again." Yet with the exception of some future professional football players, they all end up speaking the full language, pretty much.

The reason is that the sound fragments don't just fall into a void. Many of the words the adults say, those anxious discussions about where exactly to buy this thing called "pastrami", will still whir past, unable to be recognised. But a few of the words are collected, slipping easily into an amazing contraption we walk around with, loaded inside our head.

A child's brain seems pre-rigged to start re-arranging these first collected words, and send them back out as speech. But how can it possibly know which system of rearrangement will be best? This is where the parents' feedback comes in. A child in the French house will have heard hundreds of rushed phrases, and in most of them, whenever an adjective noun mix could be identified, the adjective was after the noun. The child will naturally try saying rouge after pyjamas when it points to that tattered red thing it's insisting on wearing again. An English immersed child will do the reverse.

If either of them gets it wrong the parents might offer a correction, but that's rarely necessary. Children are incredibly good at clicking the waiting brain switches into place - by the age of three their success rate is rarely under 93 per cent - and once the full panoply of adult switch-settings lock in, even greater feats can be performed. There are probably over 8,000 sentences in today's paper, and even ones you've never read before, ones thatengage in cheap tricks such as referring back to Mel's quest for the pastrami-hungering adoptee to guarantee their uniqueness, are easily enough comprehended by the parsing, sorting and analysing system built up from this implanted language potential.

Philosophers had long argued about innate ideas, but the details of this waiting switching system was only first brought out by Noam Chomsky, starting in the 1950s. It made him a star. The old-style lab psychologists, with their simple rat-and-maze models of behaviour, were wiped from the field. (How could they possibly encompass subjects able to generate an infinite number of fresh sentences?)

Sociolinguists loved the enhanced view of human motivation. When women spontaneously tell stories about themselves, for example, they often describe group action as succeeding; in men's stories, by contrast, it's usually a single hero, acting alone, who triumphs. This sort of analysis can't go far - let the tape recorder run for several hours, and a lot of the male/female language differences disappear - but something like an early switch-setting seems suspiciously involved.

Most importantly, Chomsky's early work made racism impossible. Black English had long been insulted in the US for being so crude as to actually use double negatives - as in Mohammed Ali's explanation to the chiding air hostess, "Superman don't need no seat-belt". (To which she famously replied, reaching forward to buckle him anyway, "Sure, honey chile, but Superman don't need no airplane.") Transferred into French though the negative would be perfectly allowable, simply being the ne ... pas construction for negative concord. And all three languages would seem crude compared to the Kivunjo spoken in one part of Tanzania, with its 14 tenses and seven prefixes, and suffixes, which its native speakers click into without problem - just as Mr Brooks would too, if he had been deposited there young enough for his language switches to be set in Kivunjo mode.

Tomorrow: Economics