''Madam, how dare you distort, desecrate and defile the English language...''

Jean Aitchison documents the furious reaction to her Reith lectures on language.

Madam, How dare you distort, desecrate and defile the English language as you did in your recent Reith lecture . . ." ran a letter in my postbag - one of many responses to my recent BBC Reith lectures on Radio 4. Some of the letters and comments I received were angry, others supportive: "Jean Aitchison has hit on precisely the right combination of novelty and controversy," said Robert Hanks in The Independent.

The Reith lectures were inaugurated in 1948 in honour of Lord Reith, director general of the BBC from 19 to 1938. The topics change. The first set was given by Bertrand Russell, and last year's by the architect Sir Richard Rogers. This year, it was the turn of language.

With my first lecture, I unwittingly banged the linguistic funny bone of Radio 4 regulars. The response amazed me. My pleasure at those who enjoyed the lectures was mixed with astonishment at those who ranted at me. All quite puzzling to someone who works at Oxford, where lecturers receive mainly "goal-directed attention". Students are attentive if they perceive a lecture to be directly usable in examinations, and are, at most, politely interested if not.

Perhaps I should have been prepared: "What Aitchison has embarked upon, she may not realise, is the linguistic equivalent of delivering an anti-war speech in the Pentagon," said Mark Lawson in The Guardian. For Hanks, my lecture was "all perfectly sensible advice, but handing it out to Radio 4 audiences is like trying to set the Inquisition right on theology". "Professor Jean Aitchison should bring a few million pedants swinging out of their trees," said Harold Jackson in The Guardian. And so it transpired.

"A woman wot hates English as it is writ" flamed the headline in the Daily Mail over an article in which Paul Johnson alleged that my ideas were "a frontal assault on the rules of the English language". "Mind your language, professor" was the Evening Standard headline, where A. N. Wilson announced that "What the professor says is half-baked, half true, and misses the essential point".

The angry buzz was well summarised by Philip Howard in The Times: "The Reith lecturer has poked her stick into a hornets' nest. Out buzz the crusties swollen with venom, stinging Jean Aitchison for permissiveness about language . . ." Howard used to write an informative column on words himself, and he sprang to my defence: "Who are these prescriptivists . . . ? they are white, middle-class, middle-browed males, middle-aged temperamentally if not temporally . . . They . . . find themselves in a new world, surrounded by new ideas, new words, new grammar . . . Their problem is not the decay of English, but the male menopause".

My lecture plan for the series was straightforward. "The language web" was the title, because webs can both enable and ensnare, and also because they have a preordained overall pattern. First, I discussed the cobweb of false worries that surrounds language. I then suggested how language evolved in the human species, how children acquire it, and how educated English speakers remember 50,000 or more words. Finally, I stressed that people are right to be concerned about language, though not in the ways traditionally assumed. But sweeping away the cobwebs was wishful thinking. The buzzing hornets fell into several categories.

"One-word worriers" were the most straightforward, people perturbed by my presumed misuse of a particular word, such as my pronunciation of kilOmetre: "I was saddened to hear you use that unattractive Americanism KilOmetre . . . why not (correctly) kIlometre?" "I was astonished . . . to hear you pronounce kilometre as kilOmeter. Surely, even if it is argued that language has no rights or wrongs, but merely usage, there IS sense and nonsense. The pronunciation kilOmeter is in the latter category, kIlometre in the former." Current usage suggests that both pronunciations are common. John Wells, professor of phonetics at London University reported views on some disputed usages in his authoritative Longman Pronunciation Dictionary. He notes that 52 per cent preferred the traditional kIlometre, and 48 per cent the newer kilOmetre. Clearly, two opposing influences are at work: measurements such as centimetre, millimetre, have stress on the first syllable, favouring kIlometre, but words ending in -ometer as thermometer, barometer, have stress on the second syllable, favouring kilOmetre, the pronunciation which is found in American English. Yet competing alternatives are a sign that a change may be underway. Old established forms are not automatically "right", and the language often selects for itself the variant which fits in best with current language patterns.

A second set of complaints came from the "cloth ears brigade", those who had simply not heard what I said. "The speech patterns you endorse are the direct result of downright bone idleness in the speech of the cockneys," claimed one letter writer - even though the most noticeable cockney speech feature, the glottal stop, requires considerable muscular tension, and could not be due to laziness, as I had pointed out. "Professor Aitchison . . . misses the point that we only master language by learning its shapes, patterns, and yes, rules", huffed A. N. Wilson of the Evening Standard. Yet he himself has missed the point I made by failing to comprehend the distinction between genuine rules, those used subconsciously, and artificially imposed prescriptions, such as a pedantic ban on split infinitives.

A third group of disapprovers were "gap leapers", those who leapt from a dislike of something I had said to a wider disapproval of my presumed life-style. "I find it a matter of deep regret that a person of your standing should support dirty talk on the media," ranted one letter-writer - apparently fired up by my statement that swearing is on the increase. The letter continued: "If you habitually hobnob with hippies, lesbians, drug users, Communists, etc, you may become used to it . . . I suggest you change your friends and keep better company." Yet I do not know any hippies, and have no idea whether my friends come into the other categories listed - though I would be surprised if they were drug-users, they are far too clear-headed. My mind is always boggling, according to Paul Johnson in the Daily Mail, and yes, he does make my mind boggle. It maxi-boggles when he claims that my linguistic views hand over a leftwing political message. My professional views about language have nothing to do with politics.

The "collapse of civilization" group is the most pessimistic. They adopt the "For want of a nail" scenario, where a lost nail led to a lost kingdom. Lack of care is presumed to lead to language collapse: "Clawing our way painfully and slowly from Neanderthal grunting, to Chaucer, Shakespeare, Dickens and Lord Reith, we shall descend swiftly to Neanderthal grunting again. What a waste!" someone lamented, even though I had stressed that language neatened its own patterns, and kept itself in check.

My first reaction to the furore was delight that so many people responded with interest to talks about language. My second reaction was puzzlement. Why did my lectures arouse such strong feelings? Why were so many listeners unwilling to believe what I said? After all, I have lectured on linguistics for more than a quarter of a century, and written several books on the topic - so I must know more about it than many people.

My lectures, it appears, challenged some deeply entrenched ideas about language - and such views are difficult to alter, whatever the evidence. Attitude change has long been a major interest of social psychologists. A source of authority can be persuasive, they note, but less so if the message contradicts strong beliefs. "It is not sufficient to lead the horse to the water; one must also push his head under water to get him to drink," a psychologist noted in the 1960s. But in the 1990s, it has become clear that even immersion does not necessarily force the horse to drink: it might simply kick till you let it go. This seems to be true of information about language.

I wonder if views will have changed by the time language comes round again as a Reith lecture topic? When it does, one of my correspondents from abroad is eager to deliver them: "The British intelligentsia can rest assured that the quality and standard of my lectures and their mode of delivery would be better than any Englishman's," his letter claimed. He hoped the BBC would "relish the noble idea of allowing me to teach English to the English . . . where a rot has palpably set in".

But as a final note, I waited impatiently for reactions to my second lecture, on the origin of language, the topic of my new book. The first letter firmly disillusioned me: "May I suggest that the simplest explanation of the origin of language is the biblical one - that God made men in His own image and likeness? As He is . . . a God who communicates, so He has made the human race able to communicate in verbal language." Well, where do I go from here?

Jean Aitchison is Rupert Murdoch professor of language and communication at Oxford University. Her book, The seeds of speech: Language origin and evolution is published in April and the Reith lectures later this year, both by Cambridge University Press.