People who write for children are people. There are occasions when this can be a hard position to sustain because there are some who think that children aren't people, so people who write for children must be children, too. Because we are people, we come in many different forms. The great comedian Joyce Grenfell was quite entitled to do a monologue in which the children's writer is a patronising, fey, untruthful, money-grubbing person with a particular passion for writing about middle-class children who clamber on cliffs.

I think taxi drivers are entitled to ask me if I have the mind of a child. I can even put up with the Daily Mail "journalist" who rang me up several times to challenge me quite aggressively for earning part of my living by doing performances and workshops in schools. He seemed to think that a book that costs £6 would earn me £6 and was surprised when I told him that it earned me 15p. Perhaps his main source of information about children's writers was Joyce Grenfell. Of course, I was glad to upgrade his knowledge base, along with reminding him that the conversation we were having at that very moment - along with the many other long conversations I have with salaried journalists writing articles about children's books - was earning me nothing.

So when and why are children's authors taken out of the toy cupboard and given an airing? Your rough guide to likely reasons goes like this: 1) The author of a brand-new children's book about some characters called Wifflies is a celebrity once seen in a jungle, on ice or in Buckingham Palace. 2) The author sold a billion books last week. 3) The author's writing has been described by a bishop, Tory MP or private-school head teacher as obscene, left-wing, miserable, atheistic, horrific, violent, gay or feminist. 4) A publishing company has republished an old family favourite but edited out nice old family-favourite expressions such as "nigger". 5) The author is dead, English and classic but (it has just been discovered) had a very, very small penis, was hated by his grandchildren, had an affair with Trotsky and told lies about his incarcerated younger sister "Giddyboots".

Writing for children is looked at regularly, thoughtfully and seriously in the Guardian, the Observer, their websites and the Sunday Times, but irregularly on BBC Radio 2, 3 and 4, and only sporadically (usually as special features) on television. Oddly, bafflingly, absurdly, there never has been any part of any TV programme, daytime or evening, that regularly and often helps parents, carers, relatives and teachers choose books for children of all ages.

But if you fancy being really baffled by attitudes to writing for children, then the world of education is the place to go. As a writer for children, you cannot escape the politics of literacy. Your books enter the politicised worlds of how children learn to read, what kinds of texts pupils read throughout school, what pupils are asked to do with those texts, who is responsible (if anyone) for reading out of school, library provision, and what role writers have (if any) in education. For some of us - especially if we have children of our own - this also draws us into debates about what state education should be and what childhood is.

When my first book for children came out, in 1974, I should have had every reason to know what I was doing. Both my parents were by then teacher-trainers, writers of books for teachers about children's talk and writing, with decades of experience of engaging pupils from four to 18 in literature. In fact, I was surprised by the way in which I was welcomed into the intersecting worlds of children's literature: schools, libraries, children's book groups, publishers' and editors' conferences, teacher-training courses, teachers' conferences and, on occasions, radio and TV appearances. At that very moment, policies on literacy were being thrashed out by people such as my parents alongside teachers in their professional organisations and local-authority advisers and inspectors. This was supported by a massive body of theory based on close observation of how children learn and teachers teach.

It's important here to remember that all this work was rubbished, mocked and caricatured by Tory grandees such as the singularly un-shy Kenneth Baker and then, ten years later, in one fell swoop thrown off the stage by New Labour. Literacy from three to 18 has been put through several ideological mills, which I would typify like this: 1) Mechanistic: children are like pieces of metal on a car production line. You apply short, sharp actions to them. These cause change. The changes are continued until the finished child is produced. 2) Business: teachers' input (the short, sharp actions) can be measured in terms of pupils' output (as represented by test scores). 3) Structuralist: all texts belong to a particular genre and in that genre they have a particular structure. Teaching literacy is about teaching the structure of the genre. 4) Chauvinist: English literature is the greatest in the world and pupils must be taught "major" or "key" representatives of that tradition.

We writers are drawn into this nexus. At arms' length, it might be because our books are reviewed or recommended in teachers' or librarians' journals. At close quarters, it might be because we find ourselves in a classroom or a school hall reading, talking, performing our work. But why? Across the nearly 40 years of my doing this almost every week of those years, I can see that the answer to that question has twisted and turned many times. Or put another way, in some places and in some periods, I - and writers like me - have been welcome and in other places and times we haven't been.

Scene 1 (five years ago). I've arrived in a school, invited by the head to do a performance of my poems to the whole school. In my mind, I think that doing this shows children several things at the same time: it is OK to express and relate personal experience; in sharing this collectively, orally, rhythmically and with participation we create in that moment a co-operating mini community of enjoyment; in being specific about my cultural origins, I invite everyone to be "inter-cultural"; by making the written word oral I offer a bridge to literacy that schools can carry on long after I've gone, through children's own reading and writing - for which I offer many cues and triggers.

However, as I'm walking with many children along the corridor to the hall, I overhear two teachers in front of me complaining: "We've got this poet now, haven't we? This is really interfering with my literacy hour." (Jargon alert: the "literacy hour" was the brainwave invention of the hacks who worked for New Labour, which determined what fragments of literacy (!) would be taught - and how - to every child in every state English primary school, in which year, which term and which week, and for how long.

It was "delivered" through diktat and document, policed by Ofsted, "Sats tests" and school league tables. It engaged the intellectual endeavour of thousands of advisers, inspectors, consultants and academics - many of whom did so against their own beliefs - and the whole blooming lot was junked in the last days of the New Labour regime.)

Scene 2 (three months ago). A teacher tells me that her head teacher has asked that all "real books" be removed from early years' classrooms. (Jargon alert: a "real book" is the kind of book that you see in a bookshop, like Where the Wild Things Are. The books that will be staying in the classrooms of these three-to-six-year-olds are booklets that teach children how to read through "synthetic phonics". When schools buy these schemes - so long as they are the government-approved ones - they will be given subsidies of up to £6,000 per school. Synthetic phonics is a system of teaching children to read using two methods: relating letters (and combinations of letters) to sounds; learning some whole words as whole words, for example "was" or "would", which are not "regular". Visual, contextual and semantic assistance is frowned on or banned. )

Scene 3 (a few weeks ago). I am at the Department for Education because the schools minister Nick Gibb wants to talk to me about "encouraging children to read books". He explains that he's nearly got the phonics in place everywhere. He accepts that we disagree about that, but he now wants to tackle the syndrome of "can read, won't read". My mind rocks back to a parallel universe where I sat in a room at the House of Commons trying but failing to convince a rather truculent Ed Balls and Jim Knight that if they really wanted to "lever up standards" then every piece of research from anywhere in the world points towards getting children to read independently, at home, widely, often and for pleasure (see, in particular, a more recent study: Mariah Evans's work from the University of Nevada, 2010).

Authors and illustrators for children are part of a long history of trying to engage children's interest in anything from factual, ideological, figurative and graphic traditions. Sometimes we separate ideas and feelings, sometimes we combine them. Sometimes we engage in argument and discussion, sometimes in suggestion and metaphor. Sometimes we are concerned with how cultures are represented, sometimes in how knowledge is.

I take all this to be kinds of wisdom. The makers of children's books are people who spend their lives trying to figure out ways to make this wisdom interesting and the results are there in anything from almost wordless board books through to the "young adult" books. In brief, we know what we're doing. What infuriates me - and virtually every other writer for children I meet - is that the past 30 years has seen successive governments waging war on the democratic sharing of this wisdom. One moment they've tried to control the selection, the next the pedagogy about it, the next its removal - whether by replacing it with barking at letters (phonics), an explosion of worksheets and tests based on excerpts (not whole books) or by closing libraries. This has gone on even as minister after minister has unconvincingly blethered on about this or that great author they once read or wished they had.

Sometimes you'll hear me, Philip Pullman, Michael Morpurgo, Malorie Blackman, Beverley Naidoo, Bali Rai, Melvin Burgess, Anne Fine, Alan Gibbons and many other authors expressing their misgivings about some or all of this. Forgive my rather French use of the word, but I think that that's precisely what intellectuals should be doing.

That said, more often than not it's been the persistence, humanity and courage of classroom teachers and school librarians, and their professional organisations, that has held out against this philistinism - as exemplified by the NUT's magnificent "Reading for Pleasure" documents and conferences, the Centre for Literacy in Primary Education's "Power of Reading" courses and materials, along with the work of Booktrust, National Literacy Trust, the Reading Agency, the United Kingdom Literacy Association, the English and Media Centre and many more. Writers for children work with all of them. I repeat: we know what we're doing.

Michael Rosen's most recent book is "Even My Ears Are Smiling" (Bloomsbury, £12.99)