What is the purpose of government under capitalism?

Under capitalism, a proper government’s fundamental responsibility is to protect the rights of the individual, by banning the initiation of physical force, thus making all relations between men voluntary, i.e., free from the threat of violence and fraud.

As no individual in his private capacity, as a citizen, may initiate force against others, neither may the individual in his public role as a state official start force either.

In a just society, force may only be morally used to defend or retaliate against those who start the use of force.

A proper government is permitted to use force to retaliate against a thief who has initiated force against someone (by robbing them). A proper government is not allowed to copy the means of private criminals by starting force against its citizens, no matter how “noble” the alleged goal.

Under capitalism, the government’s job is not to force people to act rationally (morally) and regulate their behavior but to use its monopoly on the use of physical force to protect and retaliate against those who start the use of force (and its corollary fraud). The government’s job is not to regulate behavior (determine what people should positively do) but to protect the individual against those who initiate physical force (to leave people free to choose what they wish to do).