The Second Amendment to the United States Constitution is plain English, fairly straightforward, and any misunderstanding is either based on the ignorance of language, or an intentional misunderstanding of the history and traditions of Western Civilization.
The Second Amendment to the US Constitution is not some complex paragraph of legal jargon, or historically contemporaneous verbage. “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.” The format is simple: There is an explanation as to what the intent of the amendment, which is to ensure the security of a free state via the means of a militia, known as the prefatory clause. This is followed by the corollary clause, which describes how the amendment is supposed to function in practice. With this is mind, the Second Amendment should be understood as this: The people have the right to keep and bear arms so that if the security of their free (as in libre free, not gratis), state is threatened, they may raise a militia to fight the threat.
Ownership of private arms is not something that the founding fathers of America were not shy or ignorant of. The idea of the modern, professional military force is a relatively modern creation, and really only could be sustained with industrialization. While at the time of the Revolution there were professional fighting forces, they tended to be smaller, elite units that were used for more precision engagements in which the majority of the forces on either side were made up more or less irregular militias. Even the British redcoat army forces stationed in the continental US were only marginally more professional than the American militia’s they engaged in the early stages of the war. American militias had their fair share of combat experience in the Seven Years/French and Indian Wars, and they were well armed to boot, boasting similar rifle and cannon arsenals that the British regular army was equipped with.
The tradition of the militia is also something that is even older than western society, with militia duty being a common responsibility throughout most societies in history. Even the modern reserve/National Guard drill schedule is loosely based off of militia duty and training schedules. As stated above, professional military forces are a fairly new concept. That is not to say that there were not professional military units before industrialization. However, the majority of armed military forces than anyone would encounter would likely be on the level of a self armed and irregularly trained militia unit, with all men likely from the same town or region. For the majority of history, if one wanted to serve in any sort of military force, just about every military unit required those who were joining to provide their own equipment such as weapons, armor, and more or less gear they would use for camping. Arms and armor had to be provided privately, in contrast to the modern military which provides each soldier their rifle, their armor, and their gear. If you were wealthier, and could afford a horse, you were promoted into the cavalry. Even missile ammunition such as arrows were largely required to be privately supplied, and archers would spend whatever time on campaign which they were not tending to camp duties, manufacturing arrows. This is of course is an exceptionally broad description of a large swath of history, but this paragraph is generally true for virtually any time period of history. Of course there will be specific exceptions. However, the majority of military history is the history of men with their own private arms.
There was a practical reason for this: arms manufacturing used to be expensive, and there were no centralized military forces that central governments had. Although this is outside the scope of this musing, centralized government in general was a fairly uncommon occurrence throughout most of history. Most of human history, local governance, and rule by strongmen, local lords, warlords, etc, was the norm. Any fighting force was raised from the population who was armed. In many societies, the change into being a man, and enfranchisement, was the requirement of owning and bearing arms when called upon. It just made sense to have the armed forces made up of men who were armed with their own weaponry. Those who could afford and were willing to bear arms, were the ones called upon to defend or fight. This was the case under feudalism, where feudal duties required vassals to perform services for their lord. Some of these services might be to provide a number of men from the town or village to fight on campaign, or to defend against a foreign threat to the realm. Even in the high Middle Ages, most armies were made up of units that were from the same town or region, with men who drilled and trained together frequently or infrequently. This was true even in modern times, in conflicts such as the American Civil War, and World War 1, where units were made up of men who knew each other. This caused problems in modern warfare, where units that took heavy casualties would devastate the population of young men from wherever they were from. This was even the case for most naval vessels throughout history. Most vessels were privately owned, and any arms onboard were property of the vessel owner.
With all of this history and tradition and practical purposes in mind, let’s consider the situation the American founders found themselves in post Revolutionary War. The war was a fight between a fairly central authority, as the Redcoat army was far more modern in weapons issued and uniformity than most other military forces, the American Continental Army, which was far more irregular and privately armed and funded, and American militias forces, which were wholly irregular. The naval battles were also mostly fought between the British and French Navies, and privateer forces. The only reason the Continental Army and militia forces were not crushed by the British was because of how heavily armed and trained they were with their weapons. While the French navy was the deciding factor in the war, the fact that men on the American continent were able and willing to put up a fight, and hold out long enough for the French Navy to exhaust the British land forces, was a testament to how necessary the private ownership of arms was to the security of a free state and to personal liberty.
To the men who were writing the Constitution, there was a lot of discussion about what would ensure the sovereignty and liberty of the people and the newly formed states. The Articles of Confederation were not written with an explicit Bill of Rights like the Constitution was due to the inherent presumption that individual arms would just be owned by private citizens as they had previously. With the collapse of support for the Articles, and the formation of a Constitution that vested far more power and authority in a central federal government, a serious concern arose that the federal government would eventually bully the people and the states to give up their liberty and sovereignty. While Federalists such as Alexander Hamilton cared more about creating an empire than maintaining liberty, other Federalists agreed with the Anti-Federalists to include specific acknowledgements of natural rights that exist inherently. Hence why the Bill of Rights exists. The Constitution does not grant someone the right to keep or bear arms, it merely acknowledges that any person has the right to defend themselves by any means necessary.
Taken down this line of thinking, it could be understood that anyone could own and bear any sort of arm needed to defend themselves, including the most powerful arms today. That is not to say that if someone wishes to own a Minuteman Mark 3 with a MIRV package, we should just hand out a fully stocked and staffed missile silo. However, I do believe that the purpose of the Second Amendment was to acknowledge a truth that was understood throughout history, and that the only way to defend personal liberty is for individuals to own the means, whether the cost bore on them personally, or through the common ownership with the intent on the defense of a group, region, or nation, was for those people to own the arms necessary to accomplish that. Nation-states today already do that, as with the nations that own nuclear weapons, and use threats of Mutually Assured Destruction to discourage foreign intervention. The United States, Russia, China, the United Kingdom, France, India, Pakistan, Israel, and North Korea will never fall from a foreign army marching on their soil, and they only have to worry about internal issues causing their government’s collapse. Each individual person has as much of a right to defend themselves and their lives as their own government does in order to continue its existence.
And if we do not believe that individual people have the capability of bearing such destructive weapons, why do we allow nation-states, made up of the very same people, the ability to wield and use such weapons under the guise of an entity such as government?