Unless a case can be made based on first principles, the case for marijuana legalization should fail on pragmatic grounds if it can be shown that legalization and the resulting increased access and use would impose significant new harms and risks on society. The medical evidence indicates that to be the case in the form of the mental illness associated with marijuana use.
For example, in 2013, in Association between cannabis use, psychosis, and schizotypal personality disorder: findings from the National Epidemiologic Survey of Alcohol and Related Conditions, the authors of a major study reported that:
The results indicate that the risk of both psychosis and SPD [schizotypal personality disorder] increases with greater use of cannabis, in a dose-dependent manner. Compared to non-users, greater cannabis use showed significantly elevated risk of having been diagnosed with SPIE [self-reported history of psychotic illness or episode] and elevated risk of all SPD symptoms, even after adjusting for sociodemographic characteristics.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4108251/
Similarly, in 2014, in Prognosis of schizophrenia in persons with and without a history of cannabis use, the authors reported that:
In addition to our previous findings of an increased risk of schizophrenia in subjects with history of cannabis use, we now show that schizophrenia patients with a history of cannabis use also have a poorer prognosis, as indicated by longer hospital episodes and more readmissions. Thus, it is of public health as well as clinical importance that, as well as increasing risk of schizophrenia, cannabis may also lead to an illness that is more severe than in non-users of this drug.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4108251/
I note that although marijuana use is apparently responsible for a greater risk of and severity of mental illness, that does not commonly amount to a certainty or probability of mental illness in otherwise healthy individuals. The cumulative effect for society though is for increased marijuana use to impose an increased burden of mental illness.
Do not take my word for any of this. Read my sources and do your own review of the medical evidence. I submit though that, unless you can refute my demonstration with evidence of a similar quality, I have won the point: marijuana legalization must logically be expected to lead to more cases of schizophrenia and an increase in their severity and burden. Within a few years, the experience of the states that have legalized marijuana will offer more definitive proof on this point.
False.
because neither of us recommend that schizophrenics drink alcohol
Who recommends that schizophrenics use marijuana? You continue to fail to establish a distinction.
or that the current mostly permissive legal status of alcohol be changed.
I recommend that laws on mind altering substances consistently reflect the reality of those substances, which pot-illegal-alcohol-legal manifestly does not.
Unless a case can be made based on first principles, the case for marijuana legalization should fail on pragmatic grounds if it can be shown that legalization and the resulting increased access and use would impose significant new harms and risks on society.
It follows from that pragmatism that maintaining the current mostly permissive legal status of alcohol fails if it can be shown that legality and the resulting increased (as compared to making illegal) access and use would continue to impose significant harms and risks on society. You continue to fail to establish a distinction between the proper legal statuses of alcohol and marijuana.
The medical evidence indicates that to be the case in the form of the mental illness associated with marijuana use.
I remind you: "Alcohol use disorder (AUD) is the most common co-occurring disorder in people with schizophrenia." - https://pubs.niaaa.nih.gov/publications/arh26-2/99-102.pdf. You continue to fail to establish a distinction between the proper legal statuses of alcohol and marijuana.
I further remind you that alcohol is more addictive than marijuana, more violence-increasing, and the only one of the two that can lead to fatal overdose.