Many phonologists in the middle part of the 20th century had a strong interest in developing techniques for discovering the phonemes of unknown languages, and in some cases setting up writing systems for these languages. The major work of Kenneth Pike on the subject has the title Phonemics: a technique for reducing languages to writing. The minimal pair was an essential tool in the discovery process, arrived at by substitution or commutation tests. Modern phonology is much less interested in such issues, and the minimal pair is consequently considered to be of little theoretical importance.
As an example for English vowels, the pair "let" + "lit" can be used to demonstrate that the phones [ɛ] (in let) and [ɪ] (in lit) do in fact represent distinct phonemes /ɛ/ and /ɪ/. An example for English consonants is the minimal pair of "pat" + "bat". The following table shows other pairs demonstrating the existence of various distinct phonemes in English. All the possible minimal pairs for any language may be set out in the same way.
|word 1||word 2||IPA 1||IPA 2||note|
Phonemic differentiation may vary between different dialects of a language, so that a particular minimal pair in one accent is a pair of homophones in another. This does not necessarily mean that one of the phonemes is absent in the homonym accent; merely that it is not contrastive in the same range of contexts.