Introduction
One of the most pervasive questions in New Testament academics is the Synoptic Problem. This is the puzzle of how the various gospels may be connected to each other as literary documents. In particular, the Problem is named for the three ‘synoptic’ gospels—Mark, Matthew, Luke—because it is immediately evident to most readers that these three are unique in sharing the same material, frequently word-for-word. For example, we have the ‘Olivet Discourse’, an apocalyptic prophecy found only in Mark 13, Matt 24, and Luke 21. Additionally, Matthew and Luke share a large amount of material nowhere found in Mark.
Aside from the three synoptic gospels, we have other texts which contribute to the ‘problem’. The Gospel of John, while immensely different in form, has some material which is oddly similar to what we find in the synoptics. Luke and John each contain stories about a man named Lazarus, whose resurrection is a topic of discussion. However, where Luke has this Lazarus found in a fictional illustration Jesus tells to make a point, John has Lazarus as a real person whom Jesus raises from death. There is the Didache, a manual apparently intended for Christian converts, which has several passages also found in Matthew and Luke. The Gospel of Peter, written in the same time frame as some of the latest New Testament books, overlaps with Matthew in certain ways. Marcion, a Christian leader from the second century and eventually declared a heretic, used a gospel very similar to Luke which yet lacked certain key sections. And there is the Gospel of Thomas, a collection of teachings from Jesus, many of which are found in Mark, Matthew, and Luke.
Two-Source Hypothesis
For the majority of modern biblical studies history, it has been accepted that none of the gospels were written by their namesake authors. Most or all of them originated anonymously, and their traditional names were attached in the second half of the second century CE. The Gospel of Mark was the first gospel written. We think we can detect the written and oral traditions its author adapted, and we can now easily observe how Matthew and Luke each edited, expanded, and rearranged Mark’s content. Yet the major concern of the Synoptic Problem is whether Matthew and Luke did this independently of each other, or if one knew the other. How else can we explain the material uniquely found in Matthew and Luke, but not Mark? The solution was to hypothesize a now-lost document as a source also used independently by Matthew and Luke, which scholars label Q (from German quelle, ‘source’).
Yet, some of Q’s contents seem to be found in Mark, as well as Thomas and the Didache. This has led to blunt suggestions that Thomas and Didache merely borrowed from the synoptic gospels, while Mark must have, yet again independently, received some items from the Q tradition. The Gospel of Peter was created from embellishing the Gospel of Matthew. Marcion, in turn, was accused by his critics in the second century CE as simply using a version of the Gospel of Luke, from which he deleted and altered passages he didn’t like. John, meanwhile, was crafted off in a different corner, mostly undisturbed by these other connections.
Competing Theories
Despite the apparent simplicity of the popular theories, they have failed to convince every scholar due to perceived shortcomings. Matthew and Luke independently using Mark and Q is doubted because the former two gospels sometimes make changes to their sources in identical ways. This has been taken to demonstrate one knew and used the other. What we call ‘Q’ may only be where Matthew copied from Luke, or vice versa.
On the other hand, Marcion contains enough dissimilarities to Luke that cannot be properly explained if Marcion is simply a cropped version of Luke. For those who suspect Luke used Matthew, the theory is called the Farrer Hypothesis. The reverse, that Matthew used Luke, is called the Wilke Hypothesis. Each of these is partly compatible with the theory of a ‘proto-Luke’, the suggestion that a post-Markan gospel was used by Luke and Marcion.
Some suggest Mark used one or more letters of Paul in crafting his gospel. Going further, John is believed by some to contain strong hints the author knew some or all of the three synoptic gospels, including some verbatim strings of text. (Or, perhaps, John was written first, and the other gospels are dependent.) There are also strong arguments that the Didache largely predates the synoptics and may have been used by Matthew and/or Luke, and that Thomas originated independently of the synoptic gospels, only later being edited into harmony with the other three. The Gospel of Peter is still thought to have used Matthew.
No matter what solutions turn out to be true, we are left with a rather messy web of how all these texts may relate to one another. The matter is which theories best explain the evidence. I sometimes take a look into solutions to the Synoptic Problem, though I admit I often find the complexities frustrating enough to avoid the topic altogether. For the moment, here is the textual genealogy I find either the most convincing or the most worth investigating.
