I think it's a question of defaults. The null hypothesis is that it won't lead to blight, violence, and widespread addiction for the same reason that most other

I think it's a question of defaults. The null hypothesis is that it won't lead to blight, violence, and widespread addiction for the same reason that most other stuff doesn't. Those fears, as the article puts it, are imaginary (though they were shrilly predicted by legalization's opponents). In other words, the bar here isn't "good evidence that legalization isn't harmful to society" but rather, "a lack of good evidence that it isn't".