I do not understand the closure of https://law.stackexchange.com/q/17067/89; law is based on opinion?
Are questions that relate to sentences, phrases, claims, or arguments in a law book necessarily on topic?
No. The fact that the source is a law book is a red herring. You must ask a legal question in order to be on-topic. Ask what the law is. Ask how the law would apply in a hypothetical. Ask for issue spotting in a scenario. Ask for explanation of a legal doctrine or interpretive canon. Ask about criminal procedure. These are legal questions.
Not all questions about the contents of a law book are questions about the law.
For example, I can imagine many questions about Scalia and Garner's Reading Law that would not be on-topic here:
- Why do they equate "beg the question" with "assuming what is to be proved"?
- Why did the Worcester County shopping center forbid leasing to restaurants whose annual sales of sandwiches might be expected to exceed 10% of the restaurant's income?
- What did the authors mean when they said it is inconceivable that a native speaker of English would refer to human deaths as "damage at a place"?
These are all questions about a law book, but they are not on-topic here. They are not legal questions. They are questions about word choices, motivations, and human nature.
To elaborate on K-C's answer, a question about an English expression like "a bridge of rationalization" is, at best, on-topic at English Language and Usage SE, and not here or at Linguistics SE (per the "language specific usage" rule). A question about the semantic principles governing the ambiguity of interpretation of phrases like "a car or truck under 20 feet long" would also be off-topic here, could be okay for English, and is best suited for Linguistics. A question about rules of legal construction that can be invoked in deciding if the law applies to a car over 20 feet long would be only appropriate here, unless you had additional text which suggested that the limit is supposed to apply to cars as well and wanted a formal discourse-analysis account to establish that conclusion (since discourse analysis is an area of linguistics). Although judges typically perform their own intuitive linguistic analysis, so that a technical analysis is usually unnecessary from the legal POV.
A possibly on-topic question related to the original would be "is 'bridge of rationalizations' a common or technical term in law?" (cf. "have standing", "statutory construction", "due diligence", "standard of review"). If, for example, you have sufficient factual grounds for thinking that "standard of review" is in fact a common technical expression in legal writing, then you can proceed to ask what exactly it means. I have personally encountered that expression at least a half-dozen times in court rulings (indeed, vastly over a half-dozen times), so I would be justified in assuming it is a legal term. There not being a recurrent pattern of legal writers using this expression, you should assume that it is not a legal term (just as "biased beliefs", a two-word expression also found in that quote, is not a legal term), and thus you need to shift your interest away from law and towards English stylistics. In the instant case, I assume that you do understand the meaning of "bridge of rationalization", and instead you're looking for "the deeper significance" or "the ephemeral connotations" behind the particular phrase, or perhaps you are asking, "Are there other literary allusions behind the expression?" At any rate, these are not questions about law.
A practical suggestion would be to assume that all questions that you might ask are not actually about legal meaning, they are stylistic questions: but this is a defeasible assumption, so if you can establish that a term has gained extraordinary and non-compositional currency in legal writing, then you might have standing to ask about the status of the phrase. "Why", in that context, is never a good question: "what" could be.