Perhaps there is an element of being hoisted by my own petard, vis-a-vis “its always been that way” but I’m not basing my argument on that.

The “benefits to society” is a moral, not an empirical claim. I’m arguing that criminalising something you do to yourself is puritan and wrong. There is of course an argument that there would be a passive smoking risk from legalisation of cannabis, but I didn’t hear that argument during the debate and I don’t see it above.

As for “who will pay”? Couldn’t the NHS receive the revenues from a cannabis tax, just like they do from cigarettes?

I also question the link between legalisation and poor life outcomes. At present, there are people who enter a) the criminal underworld and/or b) the criminal justice system, through cannabis. Legalisation would break that link. The psychosis comes from over-use, which would fall in a regulated legal market. And this might be offset by the social benefits of drug-use too. There’s no denying the positive role that pubs and alcohol plays in fostering A Good Time Had By All, and surely cannabis can play a similar role. More tokers, more seminal rock albums, surely!?

On Tom’s point about cannabis use falling in portugal, I think it’s important to remember that the only way we can measure cannabis consumption is by self report so I don’t know how reliable any statistics are. I just think that if you make something legal then it gives the message that it’s acceptable and gives the opportunity to those who perhaps weren’t going to break the law to consume it legally. In addition, those that already do consume it might increase their frequency/amount of consumption now that it’s readily available. It’s also the excess of cannabis that leads to most problems so I don’t think we should be handing it out to people.

In addition, Tom’s point that as medical students we might be biased as we are exposed to more psychotic people and so get a skewed idea of it’s prevalence in relation to cannabis. That’s not what I’m basing my ideas on and is not how medical literature works either. Medical studies are critically appraised to prevent people simply studying only psychotic patients who have consumed cannabis and working a causal relationship from that. Instead, studies have found that cannabis may alter brain functioning in susceptible individuals leading to increased risks of psychosis and psychotic symptoms. Obviously its very difficult to find a direct causal relationship because of so many compounding factors and I think the studies allow for that.

Rob, you say that “The benefits to society would be greater, and we can work out regulatory ways to reduce that risk” where does this information come from?

Finally, I was just thinking about what you (Rob) said the other night that throughout history humans have always consumed mind altering substances and that cannabis is a modern day equivalent. I know you haven’t mentioned it in your blog entry, but surely that contradicts what you wrote in ‘Vegetarianism and Religion’ that you shouldn’t justify something just because ‘ its always been that way’. I know that drugs alter the way you see the world and perhaps that’s good for art and advance, but isn’t it also a bit sad that we have to rely on substances for that and could we not reach the same states of vision via meditation etc?

Just some thoughts

Following decriminalization, Portugal had the lowest rate of lifetime marijuana use in people over 15 in the E.U.: 10%. The most comparable figure in America is in people over 12: 39.8%. Proportionally, more Americans have used cocaine than Portuguese have used marijuana.

The Cato paper reports that between 2001 and 2006 in Portugal, rates of lifetime use of any illegal drug among seventh through ninth graders fell from 14.1% to 10.6%; drug use in older teens also declined”

Also re the medical students: wouldn’t they be biased? If a fraction of the people who use cannabis suffer psychosis as a result this will be the fraction that appears in the medical literature and the fraction that med students are exposed to.

Or they could be right. It could be cannabis is harmful, but prohibition has failed to stop cannabis use, so why continue with an expensive, failed policy?

(it also depresses me that a generation of students are accepting the flaky-at-best, probably-completely-false view that cannabis causes non-trivial harm, but that’s another story for another day)