in my humble opinion -

1) protect the rights of the individual to life, liberty, and property from the majority
2) prevent and prosecute fraud in the marketplace, initiated violence (as opposed to defensive violence), and infringement on the rights of other individuals
3) establish and maintain an environment where the individual can pursue success (or failure) as an individual without undue aid (or burden) from the government that is not equally applied to all individuals

the purpose is not:

1) redistribute wealth
2) protect the individual from themselves
3) regulate beyond what is necessary to prevent infringement upon other's rights
4) enforce 'morals'
5) plan or control economic forces beyond preventing and prosecuting fraud
6) provide any material to any citizen beyond material that is provided to all citizens