The human brain is hard-wired to learn and use human language. Any child can easily learn any language – no matter how difficult it is. And then use it flawlessly – without having any understanding of it at all.
Why this is so has been baffling. But the discovery of an universal grammar, by Noam Chomsky, was a breakthrough. It showed, for one thing, that we do not think like computers – but in an entirely different way. We use parameters.
Languages are strange: they are both similar and different at the same time. And how they are similar and different depends on the settings of a limited set of these parameters. They describe the rules that are used to make any language. The rules do not resemble any language – any more than a recipe for a cake resembles a cake.
The problems with language were much like that in chemistry: what was the underlying order behind all the elements? Eventually the periodic table of the elements was deduced – after a long struggle. Then everything made sense.
Linguists are now going through a similar struggle. They have lots of clues: they have analyzed thousands of languages, and some parameters have become apparent – only some kinds of languages exist, there is not in infinite variety of them. But how the parameters all fit together is a matter of heated debate – but at least there is agreement on what needs to be agreed on.
I must repeat an important point here: computers cannot do this kind of work. We have become used to thinking that computers can do anything – after all, anything can be digitized! But language skills are an entirely different matter – they require a different kind of logic. The implications of just why this is so is one of life’s mysteries.
I cannot explain how parameters work in this posting, but one day’s lesson in a linguistic course would be adequate. Or there is an excellent book The Atoms of Language - which will carefully hold you by the hand.