I was reading David Instone-Brewer's book on the divorce-remarriage question, and I came across the following quote. He is calling attention to the similarities and dissimilarities between the way Jesus argued and the way his contemporary rabbis argued (as far as we can gather). However I think what he says here deserves attention for reasons outside the divorce-remarriage debate. It is something much more foundational he addresses.
First, he shows the axiomatic legitimacy of linguistic and historical research. Jesus could not have meant what he did not say, and he could not mean what he never meant.
Second, he reminds us that the Scriptures do not speak in code language. It speaks with all the diversity and intelligence of human language, but it is never some language other than human.
Ultimately, he gets at the heart of what inscripturated revelation really is--God speaking to humans through their own written languages so that he can be understood and obeyed.
Therefore, when Jesus used this same phrase in this same debate, it would be extraordinary to conclude that he meant something different. If we concluded this, we would have to declare that Jesus spoke a different language than that of his contemporaries, where words and phrases can mean different things when Jesus uses them. We would then have no basis for working out the meaning of lanything that he has said on any subject because he would be speaking a language that was totally unique, and any person's interpretation of his words would be as valid as anyone else's. However, if Jesus and the Gospel writers were trying to communicate eternal truths to their listeners and readers, they would presumably have used a language that was well known and understood, rather than a "sacred" langugage that had a secret interpretation. Therefore we must assume that when Jesus or the Gospel writers use the same phrase as their contemporaries, in the same context, they mean the same thing (p. 186-187).