IMO, cannabis is almost harmless, both to the individual and to society. The big problem is selfishness; self government can only work with a people who embrace purpose and duty, including the various civic duties that make self government work. So for me the question is whether legalizing cannabis would shift people's lifestyle choice toward, or away from, active, responsible, engaged civic involvement.

I have a negative bias because the potheads that I have encountered seem to be idiots who are stuck in psychological adolescence and who have a fatalistic, "I give up", noninvolved attitude toward all of the evil that they see in society. I don't have any problem at all with a person who spends his time productively, is a contributor, is engaged, and who happens to reach for a joint rather than for a beer to relax after work.