Decriminalizing possession doesn't do anything to help the violence associated with the drug trade though, does it? I thought that was one of the main reasons for the "legalize completely" argument.

Yes it does, by dramatically reducing rates of addiction and drug use. Take away vast swathes of the market for illegal drugs and the violence associated with it subsides. At least that’s what has happened in Portugal. Now that Norway is following suit, in the years to come we will have another case study to look at.

Different thing.

There aren't black markets for things that aren't illegal. Often, the gang murders we thing of are "turf wars" where one gang is competing with another gang for the same sales territory.

So legalizing drug trade likely decreases drug gangs, which likely decreases murders. People might still die from drug use, but that becomes a separate problem.

We dont know if this is true,because no developed country has decriminalised the drug trade. It seems to me that doing that would increase drug use and the associated public health and social problems. I’m much more in favour of decriminalising use but keeping the trade itself illegal, as in Portugal. That enables attacking the problem from both directions at the same time. Restrict availability through cracking down on dealers, while also removing the market through treatment and rehabilitation.

We have alcohol in the U.S. as an example; It was made illegal; so gangs moved into the import business and made more money than they had before - gangs had turf wars bigger than they had had before.

Moonshiners started making it, and sometimes it created poison.

The police were corrupted where corruptible or killed when they didn't go the gangs ways.

The rich had parties and skirted the enforcement of the law.