> The Second Amendment is widely seen as quite unusual, because it has a justification clause as well as an operative clause. Professor Volokh points out that this structure was actually quite commonplace in American constitutions of the Framing era: State Bills of Rights contained justification clauses for many of the rights they secured. Looking at these state provisions, he suggests, can shed light on how the similarly structured Second Amendment should be interpreted. In particular, the provisions show that constitutional rights will often -- and for good reason -- be written in ways that are to some extent overinclusive and to some extent underinclusive with respect to their stated justifications.
In short, the clause is there as a justification/motivation, and not a precondition, for the right to bear arms.
If the First Amendment had been written as "A well-educated legislature being essential to the governance of a free state, the right of the people to keep and read books shall not be infringed", you would argue, what, exactly?
That only the legislature had the right to books?
That only "well-educated" people had the right to books?
No, you wouldn't. Neither would anyone else, because that would be a tortured interpretation of the language.