Luke's Use Of Sources

Critics of the gospels and Acts often object that the authors didn't cite any or enough sources. When they report something about John the Baptist, Jesus, or Paul, for example, they don't tell us where they got that information. Much could be said about Matthew, Mark, and John, but my focus here will be on Luke and Acts. Luke's lack of source citation is often contrasted to the citation of sources in the best ancient works of historiography. The suggestion is often made that Luke's not telling us where he got the information he's reporting diminishes his trustworthiness to a large degree.

I'm going to cite some of Craig Keener's material on this subject. But, first, I want to make some observations of my own.

If Luke fell short of the best ancient historiographic practices, it doesn't follow that anything he said was wrong, much less that he was wrong to the degree that critics often suggest. He need not follow the best historiographic practice in order to follow adequate practice, and he need not follow the best practice in all contexts in order to do so in some.

Furthermore, we commonly accept unsourced material in modern contexts. A scientist or historian writes an editorial for a newspaper or journal without citing any sources. A news report consists of an anchor reporting an alleged recent event without any citation of sources in the process. The widow of a deceased politician, while being interviewed about her husband who died decades earlier, speaks about him without citing any sources. In our everyday lives, we often do something like refer to who the current president of the United States is or what was on television the previous night without citing any sources. And so on. Often, one of the reasons why we accept what people tell us is their general credibility or the general credibility of some other source they're affiliated with, even if no sources are cited in direct support of the particular claim that's being made. We believe a news anchor based largely on his affiliation with a generally credible news organization, for example. Ironically, the critics who object to a lack of source citation in the gospels and Acts often don't cite any sources in the process, nor do they follow the best historiographic (or other relevant) standards while raising their objections. Yet, they think what they're saying is credible.

Luke's initial audience probably knew a lot about him, especially given how he addresses Theophilus at the start of Luke and Acts. He would have had credibility as a known and trusted individual. In addition to whatever qualities he had in terms of his ethical conduct, his profession as a doctor, and such, he also was known as a close associate of Paul and somebody who had been in contact with James, for example (Acts 21:18). He was an eyewitness of some of what he reported (the "we" material in Acts). Luke is discussing events that had occurred during the lifetime of his contemporaries. When he used Mark's gospel as a source, informed readers would have known that he was thereby indirectly relying on the testimony of Peter. And so forth. Luke had a lot of credibility without citing any further sources. Yes, more source citation would have added credibility to his work and would have benefited readers like us, living thousands of years later. But Luke doesn't need maximal credibility, or even credibility that's more than sufficient, in order to have sufficient credibility.

Andrew Wallace-Hadrill refers to ancient historians as "habitually shoddy" at citing sources (Suetonius [London, England: Bristol Classical Press, 2004], 64). As he goes on to say later on the same page, "Silence is no argument for ignorance." An absence of citation doesn't prove a lack of sources, and an absence of detail doesn't prove ignorance of detail. See, also, pages 21 and 176 in the same book. Steve Mason notes that the Jewish historian Josephus usually doesn't identify his sources (Josephus, Judea, And Christian Origins [Peabody, Massachusetts: Hendrickson Publishers, 2009], 11). He also notes that it was common for ancient writers to leave details out of their writings when they could assume knowledge of those details on the part of their audience (50). He cites the comment of an ancient source, Demetrius, who wrote that "It is a slur on your hearer to tell him everything as though he were a simpleton." (50) See, also, Ronald Mellor, Tacitus (New York, New York: Routledge, 2009), 33-34, 116; Steve Mason, Josephus And The New Testament (Peabody, Massachusetts: Hendrickson Publishers, 2005), 95; Richard Bauckham, Jesus And The Eyewitnesses (Grand Rapids, Michigan: Eerdmans, 2006), n. 35 on 304.

It's not as though source citation is all we have to go by in evaluating Luke's credibility. See, for example, what I wrote in an earlier post about how archeology and other historical sources confirm the accuracy of what Luke wrote.

Keener writes:

Although Luke is less apt to name his sources than most extant ancient historians (who tended to be elite historians), he clearly had sources available (e.g., Luke 1:1-2; Acts 16:10)….

Historians usually mentioned these sources only when they conflicted or the author disagreed or was unsure about their reliability or about which sources were best. Such conflicts arose more often when they were treating events of the more remote past than when they were treating the present. Luke (like the other Gospel authors) does not identify specific sources (except perhaps "we" in Acts 16:10-28:16), probably in part because he discusses events of a recent generation on which sources have not yet diverged greatly. A historian might also more generally refer readers interested in more detail to "other historians" (e.g., Vell. Paterc. 2.48.5), not unlike Luke's oblique reference to other authors in Luke 1:1. The Gospel writers' reticence to name sources might also follow some Jewish conventions on this point; in some early Jewish works we can identify the sources only because they are extant. The more popular audience that the Gospel writers anticipated may be a more important factor in their failure to name sources; popular works of various genres were less likely to cite sources, even when they clearly depended on them….

Luke has more information available than he recounts, and sometimes this information is already known to his ideal audience (see, e.g., Luke 1:4). Thus he sometimes recounts a matter as if his audience already knows it, when in fact he has not mentioned it (e.g., Acts 9:39; 17:6)….

Likewise, Luke's usually fairly consistent style cannot count against his use of sources any more than Josephus's rewriting biblical narratives in his own style should lead us to think that he did not follow biblical accounts. Historians typically rewrote sources in their own style….

Luke's adaptation of Mark generally sticks close to Mark's stories and (with very rare exceptions) even his sequence. If this is representative of his use of written sources, Luke may stay closer to his sources than Josephus stays to the Bible in his Antiquities.

(Acts: An Exegetical Commentary, Volume I [Grand Rapids, Michigan: Baker Academic, 2012], 170-2, 176, 178, 192)

Luke tells us of his awareness of many sources without going into detail about them (Luke 1:1). He uses Mark's gospel without telling us he's doing so. When he begins narrating events to which he was an eyewitness, in the second half of Acts, he doesn't make much of an issue of it, but instead starts using terms like "we" without further elaboration. Luke had many sources, including some highly credible ones, even though he doesn't explicitly cite sources. Given what we know of Luke and his sources, we'd expect him to be credible. The historical record confirms his credibility, as I discussed in an earlier post.