Prior to the adoption of the Constitution, the state had their own. PA's then and now guarantees the rightto bear arms. at the time the Constitution was adopted, the Bill of Rights only applied to the federal govenrment. (it was not until much later the Supreme Court started applying it to the states under the 14th.) The Bill of Rights was adopted to make sure the feds did not trample on the individuals' rights so why would they adopt an amendment to deny the right to bear arms and eliminate all those state consitutional rights? They didn't. Also, the founders despised standing armies which is why the House has to pass a budget every 2 years. So, if no standing army, then state militias were assumed to always be there.