Introduction: This was posted to twitter on June 11, 2022. It is clearly an argument about the proper interpretation of the Second Amendment of the U.S. Constitution. Many similar arguments have been made online and in other contexts on pretty regular basis.
Key Facts: There are a few facts which might have bearing on the (de-)merits of this argument.
1: The Second Amendment reads as follows: “A well regulated militia, being necessary to the security of a free state, the right to keep and bear arms, shall not be infringed.”
2: Muskets were not the only weapons known to those writing the Second Amendment. They would of course have been familiar with canons. Muzzle-loading rifles had been used for hunting and even saw some use during the American revolution, and experimental forms of semi-automatic weapons such as the Gieardoni air rifle and the Belton flintlock had been developed by this time. Still, muskets were the predominant form of weapon used in warfare. I believe muzzle-loading rifles may have been more useful in hunting, but I am not entirely sure of this.
3: Much of the current discussion of gun control focuses on the prospect of banning assault weapons, or otherwise subjecting them to some form of stricter-than-usual regulation. What constitutes an ‘assault weapon‘ can be a difficult question. The difficulty is of course compounded by the controversial nature of the debate over gun control.
4: James Madison’s first official draft of the Second Amendment was proposed in 1789. The Second Amendment was ratified in 1791.
Text: “The Second Amendment is from 1789. So, technically, the second amendment only applies to muskets.”
Comments: I am using this as a representative sample of a broad range of arguments about the meaning of ‘arms’ by gun control advocates.
Statements: There are two statements in this argument.
 The Second Amendment is from 1789.
 technically, the second amendment only applies to muskets.
Discussion: This argument raises the following issues; Availability Heuristic, Contextualization, Hedges, Indexicality, The Masked Man Fallacy, Micro-Reasoning, Semantics.
Availability Heuristic: It appears that the author assumes that muskets were the only weapons available in 1789, or the only ones who count as far as she is concerned. Either way, it’s a problem. While muskets were certainly the most prevalent weapon used in war, they were not the only weapons available. So, the notion that the Second Amendment can apply only to muskets does not literally work, even as applied to the weapons of the day.
Most likely, this is an expression of the availability heuristic. In other words, the author is letting her sense of the weaponry available at the time be defined entirely by the weapons most talked about in history books and movies (which deal most often with warfare). She may even be aware of some of the author weapons of the era, but they do not stand out in her mind so much as muskets.
Just how much this matters is another question. Experimental semi-automatic weapons were not widely available at the time, and even rifles were not the main weapons of war as of yet. (Also, she may mean to include muzzle-loading rifles in her own use of ‘muskets.’ A distinction between a smooth-bore musket and a muzzle-loading rifle is probably not that common in modern thinking about guns, at least not amongst the general population.
This is probably a trivial mistake. Insofar as the author is most likely trying to distinguish between muzzle-loading weapons available in the founding era from some construction of ‘assault weapons’ today, a significant difference would not be hard to establish. So, if this is a problem, it is probably not a problem critical to her argument.
Contextualization: The issue here arises because of the contextualization behind the Second Amendment. It is a text written in a particular time and place, but it is also a text written with future generations in mind. We also read this text today under the assumption that it must somehow be relevant now. In effect, this is a text with a exceptionally broad context insofar as its authors clearly meant to speak to people not yet born on matters not yet coming to pass. The problem is thus a question about how to manage the logical implications of a text with different practical implications at different times.
Hedges: The term “technically” is a hedge. Its use indicates that the author sees her interpretation as narrow in comparison to conventional meaning. For reasons mentioned below, it is doubtful that her interpretation of the Second Amendment is ‘technically’ correct.
Indexicality: Part of the problem here is a problem of reference and predication. The text of the amendment refers to something by means of a term, ‘arms.’ What that term means in semantic terms, is one thing. What real-world objects may be referenced through that meaning is another. The problem here is a question of what specific things are referenced by means of the term ‘arms?’ The term carries certain notions, but the actual objects reference by those notions have changed over time.
Masked Man fallacy: Probably the biggest problem with this argument is its confusion of reference by intension with reference by extension. The relevant term in question is ‘arms.’ What the author asks us to consider is the fact that this term was used in 1789 to refer to a much narrower category of weapons than we could use it for today. She concludes from this that the term applies only to that narrow range of weapons from 1789 rather than the full range of arms presently on the market for civilian gun ownership. In so doing, she derives a conclusion about intensional meaning of ‘arms’ from the extension of the original reference to muskets.
This seems like the opposite of the usual form of the masked man fallacy. This fallacy treats two terms as equivalent in meaning if they refer to the same actual things even when the equivalence is not known to a given subject (e.g. Lois Lane knows Clark Kent is in New York because she knows Superman is in New York and we know that Superman is really Clark Kent). In the case of this argument by contrast, a broad intension is denied, because of a limited initial extension (to muskets only) in its initial reference whereas there is nothing in the semantics of the term that suggests it must be so limited. Those who wrote, debated and ratified the Second Amendment may not have known about an AR-15, but we have no reason to believe its characteristics would not have qualified as a form of ‘arm.’ The direction of the inference is unusual for an application of the masked man fallacy, but the author is still confounding reference by intension with reference by extension.
Micro-Reasoning: It is probably safe to say that some of the problems mentioned here are directly due to the brevity of the argument.
Semantics: The argument is explicitly about the meaning of the text in question, and many of the problems mentioned here are also a function of questions about meaning.
Evaluation: Insofar as the argument commits the masked man fallacy, or something very close to it, this argument is unsound.
Final Thoughts: There are of course many different variations on this argument, some of which may avoid the problems outlined above. What we know is what was written at the time and what weapons were in use at the time. How those who wrote it might assess the costs and benefits of the Second Amendment today is an entirely different question. It might be fair to suggest that the difference between guns in 1989 and guns today should lead us to recalculate the costs and benefits of the Second Amendment. What doesn’t work is an argument deriving a narrow intention from the general terminology based on a factual comparison between the weaponry of 1789 and that available today. You could say; “things have changed and so we should rethink this.” What you can’t say with reasonable force is that the framers meant for the Second Amendment to apply only to the weapons generally available at the time.