bradleycny said:

The correlation between cannabis and schizophrenia is undeniable. Dogmatic defenders of cannabis always argue that schizophrenics self medicate with marijuana and that it causes no psychosis.

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I don't think this is true at all.

The problem with all of these studies is that they spit out correlation and assume causation.

Now, I'm not saying that schizophrenics are massively self-medicating, that seems silly.  But there's a HUGE middle ground.  For example, as the link you posted states, the correlation exists not just between cannabis and schizophrenia, but between the entire range of street drugs and schizophrenia.

So I ask you, which is more likely under Occam's Razor: dozens of different chemicals which all react with different parts of the brain in dozens of different ways all happening to cause schizophrenia OR schizophrenics having a compulsion to try any and all drugs as a condition of the disease?  Were it the case that schizophrenics have a penchant for trying drugs in general (similar to how people with OCD all tend to focud on cleanliness), you would get the exact same results from the studies as you would if cannabis was actually a cause and not a symptom.

The exact same reasoning can apply to their numbers regarding people with a history of mental illness.  Keep in mind that there isn't actually a "6% chance" of you developing schizophrenia, they don't actually know that.  They only know that 6% of population A has schizophrenia versus 60% of population B, and then they attempt to draw conclusions.  However, if a desire to consume drugs (or it could be something else, perhaps a particular weakness to peer pressure) is infact a symptom of schizophrenia, then population B merely exhibited the symptom, and they are not actually in their own category.

Not everyone who gets the flu has a sore throat, if not everyone who has schizophrenia has a penchant for teenage drug use, that wouldn't be unusual either even if it was a major symptom.

If you wanted to develop a responsible study, you'd have to show two things: 1) What the total number of schizophrenics who use drugs looks like over time compared to the total schizophrenic population and 2) What the percentage of the cannabis using population that had schizophrenia did during that same period of time.

None of the medical studies to date have looked at both sides of this question, and so none of them have yet to adequately prove anything.

Then again, maybe I'm just jealous because I study economics and most economists are held to a higher level of statistical analysis than people who research in the "hard" sciences.