It's been a while since I discussed medical marijuana, even though it's a topic I've been meaning to come back to since I first dubbed medical marijuana to be the equivalent of herbalism and discussed how the potential of cannabinoids to treat cancer has been, thus far, unimpressive, with relatively modest antitumor effects. The reason I refer to medical marijuana as the "new herbalism" is because the arguments made in favor of medical marijuana are very much like arguments for herbalism, including arguments that using the natural plant is superior to using specific purified cannabinoids,…