"Why has government been instituted at all? Because the passions of man will not conform to the dictates of reason and justice without constraint." What does this quote mean?

The quote gives an explanation for the existence of a democratic government.

Explanation:

This quote is an impassioned argument for the nature of the government and why a modern society requires a democratically chosen government as its fundamental unit.

This statement basically wonders why the government was constituted to look at the permanent need of such institution.

It basically says that the person in society is constrained by the government and in the absence of one they will not always follow their own faculty of justice and reason  and will be wont to falter from their morals.

i would go with the last one