Actually, no you wouldn't. You'd be able to answer why Alexandra Gelber, Assistant Deputy Chief of the Child Exploitation and Obscenity Section,
thinks violence/violent imagery is different than sexual abuse/sexual imagery. The only citations are to law (both statutory and case law) but in a memo arguing for the justification of the law, citing the law is begging the question. She does make reference to a number of specific cases, but one could just as easily pick out examples of violent acts being committed by people exposed to violent imagery. In order to refute the analogy, you must show why the two situations are different; Ms. Gelber makes an effort to connect sexual images of children with sexual abuse of children but fails to
show (rather than state) how that differs from the case with violence.
Consider the passage you quoted.
"no one who watches Saw believes that the images of violence are actually happening"
Actually, you do believe it, at least for the duration of the film; the concept is known as "suspension of disbelief". Rationally, you know better, but your mind takes a temporary lapse of its senses for the sake of enjoyment. That doesn't change the fact that the violence is realistic enough to pass for the real thing.
"where in child pornography images, real children are actually being abused."
What about animated images or self-taken images? There is plenty of content produced that involves no actual depiction of children, nonetheless the abuse of children. Yet the law seems to state and the courts seem to think, for the most part, possession of images not depicting abuse constitutes the same offense as possession of the genuine article.
"Furthermore, what is the point of any pornography if not to stoke the fires of sexual desire"
I could just as easily say: what is the point of any pornography if not to satisfy sexual desire? Since I too am providing no citations for my claim, one cannot objectively state which of our two statements holds more water.
I appreciate the contribution to the discussion, but ultimately what we have (as is often the case in such matters, to be fair) is a dispute between opinions, lacking any hard evidence for either position. Remember that the position is about child pornography/pedophilia in general, so you can't just cite specific offenders; exceptional cases do not a trend make. Statistics are needed here, but obviously they're going to be hard to come by.
Also, even if we take Ms. Gelber's argument at face value, it essentially boils down to: images of child pornography are very highly correlated with acts of child abuse. If that is true, then I would certainly say it, coupled with the necessary accusations, justifies a police investigation and the issuance of a warrant. However, I do not believe that makes a compelling argument for the act in and of itself to be illegal. Sexual abuse of minors is the crime; possession of its depiction is, at best, a minor offense (invasion of a child's privacy).