It is standard in interpreting Scripture to ask questions like: "What did the Paul hope to accomplish by this passage?" or "What motivated the prophet to write this verse?" or "What must the p been thinking given that he wrote this?" These questions are interesting to ask and the answers seem to illuminate our understanding of Scripture. We investigate secular texts in exactly the same way. It potentially illuminates our understanding of Aristotle's thought to ask why he waited until Met. H.6 to give a solution to the problems of Met. Z.
But there is a crucial difference between the secular case and Scripture: Scripture is authoritative. But, I think, what is authoritative is the text that the human author wrote, rather than the human author's motivations and thinking behind that text. The inferred motivations and thinking of the human author give us insight into what the text means (more strongly, I think that speaker-meaning is the relevant kind of meaning for Scripture, but the point remains even if one denies this), and hence help us know what is being taught. But the human author's motivations and thinking, in and of themselves, are quite fallible, while, in the words of the Vatican II ecumenical council, "everything asserted by the inspired authors or sacred writers must be held to be asserted by the Holy Spirit" (Dei Verbum 11, emphasis added) and hence is true.
Let me argue for the claim that the author's motivations and thinking are not in and of themselves authoritative, though I may need to qualify it. Suppose we infer from internal and external evidence that an author wrote the text to a particular audience with the confident belief that the text would convince the audience of some proposition. Can we conclude that it is authoritatively taught that the audience was in fact convinced of that proposition? Surely not. We gain an insight into the intentions of the author, and this helps us understand what the text means, but the author's motivating belief is not authoritative. Or for an even more obvious example, from the fact that a sacred author writes a sentence s we can typically infer that he thought s was orthographically and grammatically correct and stylistically good Hebrew, Aramaic or Greek. But this claim about grammar and spelling is not authoritative. Scripture is not to be taken as an authoritative examplar of style—that would be like the confusion of apostle and genius that Kierkegaard inveighs against (this is probably a point at which Christian attitudes to Scripture differ from Islamic ones).
It is sometimes possible to infer from the fact that the author wrote a sentence s that asserts the proposition p that there is some other proposition, q, which he also believed. For instance, suppose the author writes with great emphasis that anyone who does A will be doomed for eternity. We might be able infer from the emphasis that the author believes that some people do A, or at least that it is quite possible to do A. This belief, however, is not asserted by the author and need not be authoritative. However, the belief does help us with the interpretation of what the author meant. For instance, suppose we have two ways of interpreting "A": A1 and A2. Suppose, further, that internal and/or external evidence shows that the author probably would not have believed that anybody does A1 but would have thought that some people do A2. This now gives us strong evidence for the claim that the author meant A2 by "A". Thus, probably, we are being authoritatively taught that those who do A2 are doomed for eternity. But it does not follow from this that we are being authoritatively taught that anybody actually does A2, even though our exegesis depended on attributing that belief to the author.
However, the above needs to be qualified. We must avoid the serious theological mistake of limiting the inspiration of Scripture to the inerrance of its assertions—the inerrance of assertions is a consequence of inspiration, but does not exhaust inspiration. There are large chunks of Scripture—much of the Psalms, for instance—where the illocutionary act is not assertion, but, say, prayer. Those parts are inspired as well, but the doctrine of the inerrance of Scriptural assertions says nothing about them. Similarly, even in the parts where assertion is the (primary?) illocutionary act, we should be open to the idea that something more is going on than inerrance. (Besides, inerrance is something basically negative—a preventing of error—while inspiration is a positive thing.) Thus, while what should be open to the idea that it does not exhaust the authority of an assertion of Scripture to say that we need to believe its content.
In particular, this raises the question of whether what is implicated by a text of Scripture is also authoritative. Here I will be entirely speculative. I think we need to distinguish between two kinds of implicatures. The first kind is where we can infer from some hypotheses about the text, such as that it tends to obeys Gricean maxims, that the author believed something, but the author does not intend for us to make that inference. The second is where the author intends for us to make some such inference. In the case where the author does not intend the inference, but we can make it nonetheless because we're clever, the inferred belief is not authoritative. In the case where the author intends for us to make the inference, we still need to distinguish between cases. The author may just want us to infer an autobiographical fact about him, that he happens to believe p. (For instance, maybe by a particular way of phrasing a question, the author wants to indicate to the reader which theological faction in Jerusalem he belongs to, and membership in the theological faction may be defined by believing p.) In that case, p need not be authoritatively taught. But the author may intend for us to learn that p from the text. In that case, p is authoritatively taught. Though maybe then p was in fact asserted?
In any case, in untangling these issues there is material for someone who is both interested in Biblical exegesis and philosophy of language for years of fruitful research. I am hoping that these reflections also show the necessity of a deep familiarity (greater than my passing acquaintance) with contemporary analytic philosophy of language to serious work on the theology of biblical inspiration.