The Synoptic Gospels present numerous events in different sequences. Why?
The Argument from Order
The argument from order is used by students of the Synoptic Problem, but it may also be applicable here. The argument compares the order in which individual pericopes (“stories” for our purposes) are presented in each of the Synoptic Gospels in order to try to determine which author used which as a source.
It’s worth pointing out that if presenting material in a different order is a “chronological contradiction” then there are literally scores of chronological contradictions in the Synoptic Gospels alone. Their passion narratives are more closely aligned (though not perfectly) in terms of what happened after what, but the ministry portions of the Synoptic Gospels differ wildly.
My own study of the argument from order has led me to 4 conclusions that have bearing on the question in the OP:
- None of the Synoptic authors were trying to present the material in a strictly chronological sequence
- Matthew principally organizes his Gospel by topic (like an encyclopedia)
- Luke principally organizes his Gospel by geography (like an atlas)
- Mark borrows from Matthew & Luke, sometimes following the order of one and sometimes the other (like somebody telling stories from memory)
A more extended discussion of these points in the context of the argument from order, with whiteboard drawings of relative order, is found in this video (disclaimer: I made this video).
An answer from our earliest source
That the Synoptic Gospels do not present their material in the same order has been known and discussed for more than 1900 years.
Our earliest written discussion of the subject comes from Papias, Bishop of Hierapolis, writing about the Gospel of Mark in the very early 2nd century, discussing what he had learned in the 1st century from first generation Christians. His words, as recorded by Eusebius:
The Elder used to say: Mark, in his capacity as Peter’s interpreter,
wrote down accurately as many things as he recalled from memory—though
not in an ordered form—of the things either said or done by the Lord.
For he neither heard the Lord nor accompanied him, but later, as I
said, Peter, who used to give his teachings in the form of chreiai,
but had no intention of providing an ordered arrangement of the logia
of the Lord. Consequently Mark did nothing wrong when he wrote down
some individual items just as he related them from memory. For he made
it his one concern not to omit anything he had heard or to falsify
anything. (see HE 3:39, translation by Bauckham)
If we expect the Gospel authors to write in a 21st century style, we will be disappointed. They were not trying to present a day-by-day travel log, but a collection (from what must have been a much larger pool of material) of the teachings and sayings of Jesus they believed were most important for the audiences they had in mind (even Luke, who tells us in his prologue he is writing an orderly account, doesn’t specify what “orderly” means).
The exact sequence of events surrounding the healing of Peter's mother-in-law is not 100% certain. The Synoptic Gospels do not present their material in the same order, because the authors never intended them to do so.