Tangent: I am literally unable to understand why possession of digital child pornography images is, in and of itself, a crime. I'm surprised that this is regarded as a radical position. A digitised image is an arrangement of bits on a platter or a wire. It doesn't hurt anyone.

Laws that criminalise consumption of child pornography on the theory that it aids and abets its production by routing material financial support to the source date back to a time when almost all child pornography was obtained in consideration of payment, usually by mail order. That time is long past. Free porn abounds on the Internet, and anyone stupid enough to pay for illegal porn probably deserves to get arrested. There is several orders of magnitude--literally--more child porn today than could have possibly been imagined in the wildest dreams of postal inspectors in the 1980s.

As for the idea that there is a case for criminalisation of child pornography possession or transmission based on some statistical link between child pornography and actual child molestation, that directly contravenes millenia of legal thought. In other words, it should not matter at all whether there is any scientific basis for the allegation of such a correlation or not; it's beside the point. It doesn't matter if 99% of child molesters have child pornography. That shouldn't affect the underlying principle. And the underlying principle is this:

You can't punish someone for something they could--conceivably, in some hypothetical set of circumstances--do, but have not actually done.

I really find the idea that possessing a file is a crime, let alone a rather non-trivial one, to be literally unintelligible. It is one of the most incomprehensible things about contemporary life to me. I don't understand how it's possible given the intellectual pedigree of Western jurisprudence.

Ignoring images created without using a real child, the trading of actual images is illegal for the same reason that drugs are illegal - to remove the demand. The thought goes, if there is no demand then people will stop creating images with kids.

Unlike the drugs trade, I doubt there are significant numbers of child abusers who are in it for the money. It seems like an incredibly risky business compared to other illegal activities, like drug running. And customer acquisition must be incredibly expensive. Also, as any digital file, a single image can be viewed again and again in the way that 1g of heroine can not. The supply of new images could completely stop and the back catalogue would be enough for customers.

In other words, I don't think this is a market problem so I don't see market solutions having any justification (or indeed effect).

Are you suggesting that the production of child porn is a charitable enterprise?

Except that demand destruction increases demand for substitutes, and one of the substitutes for viewing the existing child porn is abusing children to make more. There's another theory that watching child porn is a thoughtcrime that makes pedophiles more rather than less likely to go abuse children, but we've seen just the opposite with adults—rape and sexual assault stats decline as legal, adult porn becomes more prevalent. The whole mess reeks of the politician's fallacy (we must do something! this is something!) with little regard for the actual consequences, especially when they've started prosecuting teenagers over pictures of themselves.

Further, the definition of "child porn" now includes cartoon images, statements written by adults of a textual nature, and stories or other creations- by adults- depicting children.

Not to mention, many pictures our parents took of us as infants might count, as that is bad enough.

"Child Porn" has been stretched to include things that do not involve any actual children in any way, shape or form.

As for your last statement, contradictions cannot exist. I think that the presumed rationality of the "justice system" is in error.

And furthermore, I know of no Constitutionally valid principle under which the government can enact legislation for the sole purpose of preventing you from "thinking bad thoughts" or something of that ilk. So, it must hinge on showing actual harm to children. Downloading bits from the Internet does not harm children. You could argue that paying for them does, but that's not simple possession.

I just don't get it. I'd like to think I have a pretty broad mind. I'm not a radical or overly idealistic Libertarian. I am capable of comprehending abstractions, extrapolations, generalisations, and juridical pragmatism in the public interest. Still, the rationality of this eludes me completely.

I would also love a good answer. I think most people just don't think that deeply about it. When I questioned about this (as my camera was being confiscated), people were outraged at the thought of legalising child porn. And when pressed further, they will only say its morally wrong (and threatened to turn me to the police! - to which I backed down of course).

The best I can come up with is that legislators fear it will lead to copycats. Its been shown that people who hear about a suicide are more likely to both commit suicide and do it in the same manner. See http://en.wikipedia.org/wiki/Copycat_suicide. "Examples of celebrities whose suicides have inspired suicide clusters include the Japanese musicians Yukiko Okada and Hide and Marilyn Monroe, whose death was followed by an increase of 200 more suicides than average for that August month". And if you consider that copycat suicides may not have happened without the trigger suicide, the thought that copycat child abuse may not happen without a trigger child abuse is not a wild leap. And the trigger child abuse can be that harmless few bits.

I'd feel fine about losing some freedom to stop that child abuse trigger. There are all sorts of reasons why some information is protected from the public, and when that information can cause public harm but not be in any public interest the case to ban it is very strong. Child porn may be equivalent to that sort of may be "harmful and not in public interest" category which gets it perma-banned.

tl;dr maybe to stop copycats