There is a daycare center (I forget which) that needed to raise some extra money.  They decided they would do this by fining parents for being late to pick up their kids.  After the fine was put in place more and more parents began showing up late to pick up their kids.  The no longer felt a social obligation to pick up their kids, to behave well.  Once they were taxed for being late, they felt that justified their tardiness.

This same loss of social obligation occurs when the government takes our money, calls it a tax, and promises that it will be used for the ‘good of society’.  People don’t let themselves help others when they have already paid to help them.