Some say learning should be purely through play in the early years
Leading authors have joined educationalists in a push to get the government to scrap its new literacy targets for England's toddlers.
Former children's laureate Michael Morpurgo and author Philip Pullman have signed a letter to the Times calling for the new milestones to be axed.
It argues that four-year-olds are too young to meet goals such as writing sentences and using punctuation.
Ministers have already agreed to review two of the key goals.
As part of the Early Years Foundation Stage framework - which will apply to all early years settings from September - ministers wanted all five-year-olds to be able to write simple words and make attempts at more complex ones.
They also wanted them to be able to write their own names and begin to use simple sentences, sometimes with punctuation.
But evidence suggests only 46% of five-year-olds can do the first, and some 30% the second.
The campaigners want what they see as "compulsory learning requirements" to be changed to voluntary guidance.
Ministers insist these aims are not "mandatory targets but aspirational milestones".
However, the Early Years Framework does say providers have a duty to ensure that they comply with the learning and development requirements as well as the welfare requirements.
In addition, they must have regard to the statutory guidance and provide good reasons for deviating from it.
The campaigners claim key aspects of the framework have been criticised across the field and that even the government's own advisers have urged reconsideration.
Their letter reads: "Parents should have the right to choose how their pre-school children are cared for and educated.
"Young children should also have the right to be protected from an imposed system which harness their development to prescribed targets, and which may well force them into inappropriate early learning."
Children's minister Beverley Hughes said the EYFS framework was highly flexible and based on the best practice that already exists in the childcare sector.
"However a small number of parents and childcare providers have told us they feel that some specific parts of the EYFS are incompatible with their philosophy.
"I have listened to these views and whilst we believe the EYFS to be compatible with their philosophy, we have agreed that a time-limited exemption process should be possible, so we can monitor the implications of the EYFS in these particular settings and inform our review in 2010.
"The first few years of children's lives are really special because they are learning more and faster than at any other time in their lives.
"Children's experiences in the early years make a difference for years to come, and gaps open very early on between children from richer and poorer backgrounds.
"I believe that every child in this country is entitled to the benefits of learning through play as set out in the EYFS."
But the campaigners say that parts of the learning requirements set some children up for failure and that those who are less academically bright and do not come from middle class homes were particularly at risk.
Other signatories to the letter include Professor Tim Brighouse of the Institute of Education, London; psychoanalyst Professor Susie Orbach and childcare author Dr Penelope Leach.