What is the 4 source theory

- The four-source theory is the theory that the 3 Synoptic Gospels in the Triple Tradition was written with four different sources - The two earlier sources were Mark (Luke and Matthew both contain a large portion of content that is similar or identical to Mark’s), and ‘Q source’ – material that sits within the ‘Double Tradition’, and is common to both Luke and Matthew but is not found in Mark. - Matthew and Luke also contained their own unique information (the Single Tradition)