..The progressive education movement was inspired by Dewey's writings but was not always strictly loyal to Dewey's intentions. The movement encompassed four significant ideas. Taken together, these ideas undermined the premise that all children should study a solid academic curriculum. Indeed, they raised doubts about the value of a solid academic education for anyone.
First was the idea that education might become a science and that the methods and ends of education could be measured with precision and determined scientifically. This was the basis of the mental testing movement.
Second was the idea that the methods and ends of education could be derived from the innate needs and nature of the child. This was the basis of the child-centered movement.
Third was the idea that the methods and ends of education could be determined by assessing the needs of society and then fitting children for their role in society. This was the basis of the social efficiency movement.
Fourth was the idea that the methods and ends of education could be changed in ways that would reform society. Proponents of this idea expected that the schools could change the social order, either by freeing children's creative spirit or conversely by indoctrinating them for life in a planned society. The first version was the faith of the child-centered movement and the second was the basis of the social reconstruction movement.
It's interesting because while three of these "movements" tend to consider the child as a cog in society of one kind or another, the "child-centered" movement is almost the opposite. As the book points out, "child-centered" IS appropriate if considered properly. The only proper end in the education of an individual is the perfecting of that individual's capacity. Since an individual's potential is only properly fulfilled in a social, civic role, according to Aristotle, the individual's progress benefits society in general.
However, and this is crucial, benefiting society can never be the proper end of education. This would make Society more important than the individuals which make up society. In actuality, society is for the betterment of people; people are not for the betterment of society. So, people ought never to be educated merely to fit some role.
"Child-centered" too often became co-opted by other motives. It often trapped the child into a world of what was directly around it, or what was thought to be directly "relevant" to it. It became the adult's conception of the "child's world", and thus what Charlotte Mason called "twaddle".
Children do not really need "help" doing what they already can do and want to do. They don't need to go to school to learn how to be children, especially to be taught by adults who have only a vague, scientific idea of what a child is. If that is all there is to it, they may as well not go to school. That is where other motives came into the "child-centered" picture and utilitarian motives for schooling came in -- children need to be confined, children need to be taught functional skills, children need to learn the rules, children need to be tracked by their mental gifts or lack of them. At the very least, this necessarily pulls the agenda away from "child-centered" and towards something outside the child. And it's a lesser thing, acknowledging function at the expense of development.
On a deeper level, and I am trying to think this out as I write so it may not come out the way I want it to -- a true existential understanding of what something is essentially involves a a sense of what it is becoming. While contemplating an acorn, you are unlikely to have a proper sense of its essential qualities if you don't happen to have a sense of its potential and "final end".... why it is there and what it can be. If asked then to care for it in an "acorn-centered" way you might even do something like put it in a box with a bunch of other acorns and try to encourage it to behave more like an acorn, more round and compact, and less like the first stage of a seedling. The analogy is not complete but you get the picture. The acorn certainly has different requirements than the oak stripling or seasoned tree, and it is appropriate to acknowledge this and make provisions for this, but not to wrap it up in a perpetual acorn world.
Children are apprentice adults. They have the same qualities that any person has, only in a more impressionable and susceptible form. They desire to become competent adults, as John Holt and Jean Liedloff said. They require some shelter and mediation between them and the world, otherwise there would be no real need for parenting, but they generally don't want to be hedged into an adult's version of the "child world" . If treated so, they find their own escapes.