In defence of underlying representations: Latin rhotacism, French liaison, Romanian palatalization

The surface realization of a linguistic expression can often be
predicted from the form of paradigmatically related items that are not contained
within it: in Latin, the nominative singular of a noun can often be
inferred from the genitive; in French, the final consonant of a prenominal
masculine adjective in liaison can typically be predicted from the feminine;
in Romanian, the plural form of a noun determines whether its stem will
exhibit palatalization before the derivational suffix /-ist/. Such instances of
phonological paradigmatic dependence without containment have been
claimed to challenge cyclic models of the morphosyntax-phonology interface.
In this article, however, they are shown to be established indirectly through
the acquisition of underlying representations. This approach correctly predicts
that phonological paradigmatic dependencies are never systematically
extended to new items if they involve suppletive allomorphy rather than
regular alternation, whilst those surface phonological properties of derivatives
that are under strict phonotactic control evade paradigmatic dependence on
the inflectional forms of their bases. Theories relying on surface-to-surface
computation fail to recover these empirical predictions because they are
inherently nonmodular, positing generalizations that promiscuously mix phonological, morphosyntactic, and lexical information. Underlying representations, therefore, remain indispensable as a means of establishing a necessary modular demarcation between regular phonology and suppletive allomorphy.