The document discusses how to choose an underlying form for morphemes. There are two main considerations: 1) the underlying form should be the allomorph that occurs in the most environments, and 2) it should be the hardest to derive by rule. For the English plural morpheme, the underlying form is argued to be /-z/ because it occurs in the most environments and can be derived from an epenthesis rule inserting /i/, making /-s/ the simplest rule. The underlying form should reduce the number and complexity of rules needed to describe the language.

1. How to pick an underlying form
BY : ZAHRA AAMIR

2. • Underlying form is expressed in terms of phonemes.
• The underlying form of morphemes is often written as {-s},representing the
underlying form( with phoneme /s/ ) of the plural morpheme.
A property of a morpheme or the abstract form that the morpheme
is postulated to have before any phonological rules have applied to it.
Underlying form

3.  There are two basic considerations in choosing an
underlying form for a particular morpheme :
1- The underlying form should be the allomorph that occurs in the
largest number of environments.
2- The underlying form should be the allomorph that is most difficult
to derive by a rule.

4. Data on English Plural

5. • The allomorph |-z| appears after vowels and fricative, plosive, lateral,
and approximant consonants.
• There are more different kinds of situations in which the |-z| allomorph
appears than any of the others .
• These patterns represent both assimilation and structure preservation.
• The voiceless allomorph (|-s|) only appears after voiceless sounds.

6. • The|-z| allomorph can be thought of as the result of an insertion, or
epenthesis, rule that inserts an i vowel in order to preserve normal
English word structure.
• Epenthesis means the addition of a sound to a word in order to make
pronunciation easier.
• The words would end in sequences of consonants that never appear
at the ends of words in English
• English speakers would say these sequences are “hard to pronounce”
(though they may be totally natural in other languages).

7. The final form of the morphophonemic rules for the regular
PLURAL is :
|-s| ,|-z |, |-iz |
The best underlying form is the one
that occurs in the largest number of
environments ,and /or that results in
the simplest rules.

8.  Linguists are always interested in reducing the number
and complexity of the grammatical rules they posit for
language.
 The assumption is that if two rules will both work, the
simpler one is more likely to accurately represent the
mental processes involved.

9.  Conclusion
Spelling is not evidence for or against morphophonemic analyses. The fact that
the plural morpheme is spelled with an s letter in English writing has nothing to
do with what the underlying form should be. Sometimes spelling can suggest
hypotheses, since spelling often represents pronunciations at earlier stages of
the language, and underlying forms are generally historically older than the
allomorphs. However, spelling itself does not constitute evidence for
morphophonemic analyses.