Here's a fragment of a common argument in support of displaying the Ten Commandments in courtrooms:

The Ten Commandments are the source of American law
Therefore: The Ten Commandments should be displayed in American courtrooms.

The implicit premiss might be:

If some document is a source of American Law, then that document should be displayed in American courtrooms.

Actually, the implicit premiss should be something more general, but that makes it somewhat harder to formulate. Something like:

If some document is of historical importance to x, then x should post the document.


The argument is extremely weak, and rather obviously so.

First, it isn't clear that the premiss is true. It'd be great to hear from someone who knows about the history of law on this point.

Second, the implicit premiss is false. The mere fact that some document played an important role in the history of the law dosn't mean that we have an obligation to display that document in the courtroom. And, in fact, it doesn't even entail that we are permitted to do so. It is relatively natural and common to display documents of historical importance in relevant places--for example, if an organization has some kind of founding charter, it might make some kind of sense to post a copy of that charter in the office of the organization. The organization, however, has no duty to do so, and would not be remiss if it failed to post a copy of its charter. To post the charter makes some kind of sense because it is relevant and might be of interest to those associated with the organization--basically, it would make an interesting and sensible decoration. A tank commander in the US Army might choose to post a copy of the Gettysburg address in his tank because it would constitute a poignant reminder of an important part of our country's military history. However, there might be regulations about posting stray pieces of paper in the tank under combat conditions (since they might, say, pose some kind of hazard by covering instrumentation). So, though the document is relevant and it makes some sense to post it, there is clearly no obligation to do so, and there might be very good reasons to prohibit its posting. The case of the Ten Commandments is similar. IF the Ten Commandments are, in fact, of historical imporance to American law, then a copy of them might make a natural and interesting bit of decoration. But that isn't enough to generate an obligation to post them. And, furthermore, there are excellent reasons for NOT posting them, since that would be a clear violation of the First Amendment.

Some people dispute that last claim, but (a) they are wrong and (b) that's a different issue. Here I'm only concerned to discuss the weakness of the argument from historical relevance.