What evidence supports the theory that Matthew and Luke used Mark as a source for their gospels?

There are numerous instances where Matthew and Luke contain identical wording that is also found in Mark. This verbatim agreement suggests that one or both of the authors had access to Mark's Gospel when writing their own accounts.

The Synoptic Problem is a fascinating topic that explores the relationship between the three Synoptic Gospels - Matthew, Mark, and Luke. One of the proposed solutions to this problem is the theory that Matthew and Luke used Mark as a source for their Gospels. This theory is supported by several pieces of evidence that highlight the similarities and differences between the three Gospels.

One of the primary pieces of evidence supporting the theory that Matthew and Luke used Mark as a source is the verbatim agreement between the three Gospels. There are numerous instances where Matthew and Luke contain identical wording that is also found in Mark. This verbatim agreement suggests that one or both of the authors had access to Mark's Gospel when writing their own accounts.

In addition to verbatim agreement, the order of the material in Mark is often followed by Matthew and Luke. This order is not always preserved, but when it is, it suggests a direct influence of Mark on the other two Gospels. The presence of the "triple tradition" - material that is present in all three Synoptic Gospels - further supports the idea that Matthew and Luke used Mark as a source. The triple tradition includes many of Jesus' teachings and parables, as well as some narrative material, and its presence in all three Gospels indicates a literary relationship between them.

Another piece of evidence that supports the theory that Matthew and Luke used Mark as a source is the phenomenon of "editorial fatigue." This occurs when an author inadvertently repeats or contradicts themselves due to working with multiple sources. In the case of Matthew and Luke, there are instances where the editing of Mark's material seems to result in fatigue, as they overlook details introduced in Mark but change elements later on in their own accounts. This suggests that they were indeed working with Mark and making changes to the text as they wrote their own Gospels.

Some scholars also point to the differences between the Gospels as evidence for Markan priority. The idea is that Matthew and Luke made revisions and additions to Mark's Gospel, which would explain why there are instances where they differ from each other and from Mark. The theory of Markan priority provides a compelling explanation for these differences and similarities.