As copies multiplied, so did the textual discrepancies. A scribe may intentionally have altered the text for any of a number of reasons, or perhaps a transcriptional error has come into play. In order to judge a particular reading, one must first construct its history. These two principles provide the larger framework, but other principles enable us to make reasonable judgments in specific cases. First, there is external evidence .
External evidence has to do with the various manuscripts themselves.
The date of a particular reading is important. In this case, it is not primarily the age of the manuscript that matters, but our ability to trace particular readings to types of texts with strong and ancient pedigrees. Some later mss. The geographical distribution of a reading is significant, though often difficult to discern for beginning readers. The text-type of a manuscript source can be significant.