In a free society, many conflicting harms are settled through the institution of private property rights. Private property rights have to do with rights belonging to the person deemed owner of property to keep, acquire, use and dispose of property as he deems fit so long as he does not violate similar rights of another.
Let's say that you are offended, possibly harmed, by bars that play vulgar rap music and permit smoking. If you could use government to outlaw rap music and smoking in bars, you would be benefited and people who enjoyed rap music and smoking would be harmed. Again, there is no scientific or intelligent way to determine whose harm is more important.
In a free society, the question of who has the right to harm whom, by permitting rap music and smoking, is answered by the property rights question: Who owns the bar? In a socialistic society, such conflicting harms are resolved through government intimidation and coercion.