There are eighteen and only eighteen fundamental ways in which three documents, among which there exists some kind of direct literary dependence, may be related to each other. While it is possible to conceive of an infinite number of variations of the eighteen basic relations by positing additional hypothetical document, these eighteen should be given first consideration. Only six out of the eighteen basic hypothetical arrangements are viable. There are agreements of any two against the other, so one gospel must know both of the others, and one of the others must know the other one. There are isolable and objectively definable categories of literary phenomena which have played a prominent role in the history of the Synoptic Problem which properly understood are more readily explicable when Mark is placed third than when either Matthew or Luke is placed third.
Farmer refers to the phenomena in the three following headings.
The phenomena of agreement and disagreement in the respective order and content of material in each of the Synoptic Gospels constitute a category of literary phenomenon which is more readily explicable on a hypothesis which places Mark third with Matthew and Luke before him than on any alternative hypothesis. This is the pattern of Mark's alternating agreement in order between Matthew and Luke. See the parallel synoptic table for the pattern. The Minor Agreements of Matthew and Luke against Mark constitute a second category of literary phenomena which is readily explicable on a hypothesis where Mark is the regarded as third with Matthew and Luke before him than on any alternative hypothesis. There exists a positive correlation between agreement in order and agreement in wording among the Synoptic Gospels which is most readily explicable on the hypothesis that Mark was written after Matthew and Luke and is the result of a redactional procedure in which Mark made use of both Matthew and Luke.