What kind of speaker data does studying a language phonologically involve examining?
Part of the phonological study of a language therefore involves looking at data (phonetic transcriptions of the speech of native speakers) and trying to deduce what the underlying phonemes are and what the sound inventory of the language is. The presence or absence of minimal pairs, as mentioned above, is a frequently used criterion for deciding whether two sounds should be assigned to the same phoneme. However, other considerations often need to be taken into account as well.
Brooke Foss Westcott (1825–1901) and Fenton J. A. Hort (1828–1892) published an edition of the New Testament in Greek in 1881. They proposed nine critical rules, including a version of Bengel's rule, "The reading is less likely to be original that shows a disposition to smooth away difficulties." They also argued that "Readings are approved or rejected by reason of the quality, and not the number, of their supporting witnesses", and that "The reading is to be preferred that most fitly explains the existence of the others."