So what about depictions of murder?
If depictions of murder could be used into desensitizing children and eliciting sexual behavior, they should also be criminalized. However, since they can't be used to manipulate children into cooperating in their own sexual exploitation, they present no problem.
The problem with child porn is not that it stimulates pedophiles, but that pedophiles use it to stimulate children into cooperating in their own victimization. It is the mental and emotional manipulation of the child by a cunning adult that is as equally harmful and sometimes more harmful than the actual physical harm. It is a vicious thing they do, betraying faith and trust, twisting admiration and affection, scarring children permanently and to the marrow to satisfy their personal sexual desire. Why should we not outlaw photographic, pictorial and digital reproductions of such a vile act of exploitation and violation.
A child's natural right to protection and nurture is greater than the natural rights of freedom, expression and self determination possessed by adults.
The natural right of a child to be free of sexual exploitiation is greater than any adults (individually or culturally) right to view them as sexually exploitable in any medium.