Don't equate smoking marijuana to beating another human being. I've never even tried it, for the record, but I don't see anything wrong with getting high if you want to, as long as you don't cause harm to others.
Anyway, back to topic. The point is that Singapore has one of the lowest crime rates in the world [2], that doesn't come ouf of nowhere and is bought with very strict laws. Actually i was trying to make a point to not equate your own understanding of legality with another. We are all bound by certain laws and what we take for granted may sound very strange to others. For example, i find it very, very strange that, in the U.S., people are allowed to carry guns. Can't get it in my head. But well...
[1] http://io9.com/5859291/krokodil-russias-designer-drug-that-w... [2] https://en.wikipedia.org/wiki/Crime_in_Singapore
That seems to be a side-effect of prohibition though, not the drugs themselves. It was the same when alcohol was illegal in the US. If the drugs weren't illegal, would this still be the case?