Mark Shea wrote: "I'm of the opinion (perfectly acceptable, though not, of course, mandatory for Catholics) that Tobit is a work of fiction." I suppose people may differ over what is "perfectly acceptable." In Denzinger's "Sources of Catholic Dogma" the "Decree of Damasus" supposedly from a Council of Rome of 382 lists the book (consistently referred to as Tobias in Denzinger) within the list of "histories" together with Job, Esther, Esdras A & B, Judith, and 1 & 2 Maccabees. (p. 34) Likewise in a letter to Exuperius, Innocent I categories the book within the "histories" category, additionally including 1 & 2 Chronicles in the same category. (p. 42) Trent, Session IV, does not explicitly state whether Tobit is historical, but places it amongst the historical works, after Nehemiah, but before Judith, Esther, and Job.
Likewise John Paul II refers to it as historical:
1. The Liturgy of Lauds has gathered among its Canticles a fragment of a hymn, that is placed as a seal on the history narrated in the biblical Book of Tobit: to which we listened a few moments ago. The rather long and solemn hymn is an expression typical of Judaic prayer and spirituality, which draws on other texts in the Bible.(General Audience, August 13, 2003)
Where is any tradition that it is fiction?
Yes, the version of the Bible approved by the U.S. Council of Bishops (NABRE) in its notes does identify the book as historical fiction, but then again it also says the same thing about Judith and Esther: "The inspired author of the book used the literary form of religious novel (as in Esther and Judith) for the purpose of instruction and edification. The seemingly historical data, names of kings, cities, etc., are used as vivid details not only to create interest and charm, but also to illustrate the negative side of the theory of retribution: the wicked are indeed punished." (source) But who before the 20th century believed such a thing?
Luther himself was on the fence about the matter (as quoted by Fitzmyer in Tobit (Commentaries on Early Jewish Literature), p. 31). Who before Luther appreciated that the book might be fiction?
Mark Shea stated: "The clues in the text strongly suggest this, as when Tobit is named as the uncle of Ahiqar, a figure out of ancient mideast folklore." On the one hand, we may believe that Ahiqar (and the work, "The Story of Ahiqar") is fictional. On the other hand, it is not clear that the author of Tobit or that author's immediate audience were aware of the fact that Ahiqar was fictional.
Indeed, Roman Catholic historian Joseph A. Fitzmyer, in his commentary on Tobit, asserts that Ahiqar "may well have been a historical figure" (p. 37). So, while Shea may be right that the person is a character in middle eastern folklore, folklore grows up around historical figures (the cherry tree story about George Washington comes to mind - or the story of the Assumption of Mary).
Mark Shea continued: "If you want to get a feel for how that sounded to the original audience, imagine telling a tale to an English speaker that announces its hero as the uncle of Jack the Giant Killer. Your audience instantly knows from such a cue what sort of story it is hearing and interprets it accordingly." What is missing is any documentation at all from Mr. Shea that anyone at all had that perception of the Story of Ahiqar during the inter-testamental period when Tobit was written. While the Story of Ahiqar (as it has come down to us in various fragments) may have epic qualities, it's not like "Jack and the Beanstalk" in terms of making reference to magic, for example. Indeed, clearly Fitzmyer (who is an actual historian) doesn't think that Ahiqar is a virtual Jack the Giant slayer.
Mark Shea continued:
That said, I guess I see no reason why God could not inspire a folk tale that begins "Once upon a time". Jesus told fictional stories all the time. There was not really a Prodigal Son. There was not really an unjust judge, or a man who found a pearl of great price, or Good Samaritan. What's wrong with an Old Testament author doing likewise and obeying the conventions of a good "entertaining angels unaware' yarn in order to show virtue triumphing over evil through patient endurance?One obvious difference between Tobit and Jesus' parables is that Jesus' parables are - you know - described as parables. Tobit, on the other hand, is provided with lots of supposedly historical details that are actually garbled and erroneous (not just claiming that the main character is a relative of fictional Ahiqar, but a number of other issues).
Mark Shea again: "Not, I repeat, that you have to think Tobit is fiction. Lots of people in antiquity took it for a factual story. I don't think it matters." First, if it's a "factual story" then it matters if one of the main characters claims to be related to a fictional character or if the book is riddled with (other) historical inaccuracies (and it is). As Fitzmyer concedes, "the vast majority of modern commentators" acknowledge it is not historical, even though there were some attempts to defend its historicity at the beginning of the 20th century (p. 31). The reason that they acknowledge it, is that the book has so many historical blunders (depending on which recension you follow).
Second, who in antiquity did not take it for a factual story? Can Shea name even one? Even the authors who allegorized it did not argue that it was allegory as distinct from history.
Mark Shea yet again: "And the people who took it for a factual story don't seem to have spent a lot of time worrying about it." This might be significant if anyone at all had "worried" about it. Shea doesn't (probably because he cannot) point to any author before the Reformation who "worried" about whether Tobit was a purportedly historical work or whether it was an historical novel.
Rather, as noted above, the few "sources of Catholic dogma" that address the matter unanimously describe it as historical. And we could add to that the writings of people like Origen who treated the work as historical in his Letter to Africanus, at section 13 (link).
Mark Shea once more: "The Fathers of the Church who comment on Tobit are not, as is their custom, super-concerned with whether it is factual." What "Fathers" does Shea have in mind? Who besides Bede the Venerable (who died in the 8th century) provided a commentary on Tobit? Who before the 15th century took any serious in the book besides Bede and Ambrose?
As Geoffrey David Miller explains in “Marriage in the Book of Tobit” (p. 14):
Christians have read the Book of Tobit for centuries, but scholarly interest in the book is a relatively recent phenomenon. Ambrose of Milan (339-97) wrote a commentary on Tobit in the fourth century entitled De Tobia, but it was a condemnation of usury rather than an analysis of the story. The eighth-century commentary of Bede (673-735) focused on the actual story of Tobit but only in a superficial manner, offering a mere summary of the book while Christologizing it (For example, Tobiah’s victory over the fish in 6:3-4 represents Christ’s victory over Satan).Mark Shea again: "What they are interested in is what God is saying to us through the story and so they mine it for its moral teaching (primarily) and (secondarily) for its allegorical meaning concerning Christ." Which, as far as it goes, is true, with Ambrose being an example of the former, and Bede being an example of the latter.
After a quotation from Reardon (who uses the term "historical" in describing the work, repeatedly, without ever acknowledging that Tobit is historically inaccurate, either in that article or the follow-up) that we can pass over for now, Shea concludes:
As to why the Pope keeps it in the Bible, it's not the Pope's Bible to fiddle with. The Pope is bound by apostolic tradition. The apostles accepted and used the canon of books found in the Septuagint (including Tobit). So the Pope accepted it as Scripture because the apostles taught him to. Once the canon of Scripture is defined, the Pope has no authority to contradict what the Holy Spirit has spoken through Holy Church. Nor do we. Scripture is not there to affirm our aesthetic choices, but to reveal divine truth to us on God's terms, not ours. The healthy approach to Tobit is therefore to let it challenge you, rather than for you to ignore it. Why not try a decent commentary on Tobit that draws on the Catholic tradition to see what the great saints and thinkers of the Church have mined from it?
First, the "canon of the Septuagint" depends on what century you look at. Suffice to observe that Trent did not adopt Septuagint Esdras A (see discussion here) or a variety of other "Septuagint" books, such as 3 and 4 Maccabees or 1 Enoch.
Second, the idea that the Apostles used Tobit (as Scripture) is not historically supportable. The historical evidence is that the Jews of the 1st century did not view Tobit as Scripture, just as the Jews of the patristic era did not(see Origen's letter to Africanus, linked above, for evidence of that from the first half of the 3rd century), and just as modern Jews do not. We have Josephus' testimony regarding what 1st century Jews accepted as authoritative.
Third, the same "tradition" that supposedly passed down to Trent that Tobit is canonical also passed down that it was historical (as shown above). Moreover, Trent did not depart from the arrangement of Florence and left Tobit and Judith amongst the historical works.
Finally, if Tobit were inspired Scripture, Mark Shea's last few lines might make some sense. The problem is that Tobit is not Scripture. It's an uninspired work of historical fiction that was passed off for centuries as though it were an historical work. While it may have some useful teachings, so may the Story of Ahiqar - so may many other uninspired writings.
P.S. It's interesting to note that a statistically insignificant sample of readers at Catholic Answers Forums voted by a simple majority (14 out of 27) that Tobit is entirely true (link).