Peter Hitchens’ fantasy-based drug policy

A few people have asked me why I got involved in debates with Peter Hitchens, given the slim probability that he would change his opinions. I answered that I wanted to expose the weakness of his argument.
In his two replies to my blog on our debates, this weakness is on open display. Hitchens finishes his second reply by writing in typically hyperbolic style about people who argue for decriminalisation of drug possession. According to him, we are ‘scrabbling away at the last scanty defence we have against a yelling, moronic inferno of self-indulgent chaos’.
So he thinks that criminalisation of possession is a defence against chaos, presumably because it deters drug use. Why does he think this, when I have repeatedly told him about the lack of evidence for this effect? In his first reply, he makes it clear, first, that his argument rests not on fact but on fantasy and, second, that in order to maintain his argument he is ready to discard the best evidence we have on rates of drug use.
On the first point, he writes ‘there is no such place and no such time where policies of the sort I favour are in use or have been in use in the modern era, so we are unable to compare ourselves with it… it strikes me as likely that a strongly enforced law against cannabis possession would deter its use.’ This shows clearly Hitchens’ preference for imagination over evidence. He wants us to use punishments for drug possession that are in excess of those that any western democracy has been prepared to deliver. And this is not because serious studies have shown that increasing punishment actually reduces drug use (they have repeatedly not shown this), but because of what he imagines would be the effect. This is fantasy-based policy making.
On the second point, he is unwilling to accept that rates of cannabis use actually fell after the 2004 introduction of the cannabis warning. These figures come from the Crime Survey for England and Wales (formerly known as the British Crime Survey). This is not a perfect measure, but it is the highest quality study of drug use prevalence in Europe. It is certainly better than the guesswork based on media reports which Hitchens apparently prefers. The reduction in cannabis use has also been found by a different, high quality study; the survey of Smoking, Drinking and Drug Use Among Young People in England. It also shows up in the European School Survey Project on Alcohol and Other Drugs. Admissions to hospital for cannabis related psychosis also fell after 2004.
Hitchens notes that this finding apparently conflicts with reports of the ‘blossoming’ of cannabis production within the UK. This can be explained by the shift of the market, from imported cannabis resin to domestically grown herbal cannabis. Even as the market has shrunk, British police services have detected an increasing number of producers who are willing to meet the demand that remains.
If he is true to form, Hitchens will accuse me of not attending to various points that he has raised. In anticipation, I can only reply that if I were to respond to every accusation, contradiction, exaggeration, distortion, supposition and tendentious insinuation in his writings on this subject, it would try the patience of the most fascinated reader. And I have a day job to do. The point where my opponent is relying on fantasy and denial of the available data in order to support his case seems a good time to let it rest.