I think it is is anti-scientific – whether that has a pernicious effect, I don’t know…
I think looking back to my own childhood, the fact that so many of the stories I read allowed the possibility of frogs turning into princes, whether that has a sort of insidious [e]ffect on rationality, I’m not sure. Perhaps it’s something for research.
In fact, Dawkins goes further than simply advocating that children should not read Harry Potter. He thinks identifying children by their religion or even teaching them your religious views, is child abuse:
Do not ever call a child a Muslim child or a Christian child – that is a form of child abuse because a young child is too young to know what its views are about the cosmos or morality [...]
It’s a form of child abuse, even worse than physical child abuse. I wouldn’t want to teach a young child, a terrifyingly young child, about hell when he dies, as it’s as bad as many forms of physical abuse.
It is worth noting that Dawkins also once advocated that legal action be taken against astrologers under trade laws.
Now, I am an atheist. However, on the Harry Potter issue, I am more inclined to agree with the Althouse commenter who writes:
Does he have kids? Does he remember being a kid? Does he approve of the way our culture infantilizes children through and beyond the age of 18?
To which I could add some more — does he understand freedom? Imagination? The simple fact that indulgence in fantasy is a necessary component of growing up?
Also, I am disturbed by his tendency to impose rationalism via coercion. For a very personal take on coercion vs science, read this old entry of mine.