to generative grammar (e.g. HPSG (Pollard and Sag 1994), earlier LFG (Bresnan 1982a), and Hale and Keyser 1993)),
thecombinationof stems and affixes into grammatical wordsis taken to be accomplished“in thelexicon”by so-called
lexical rules (section 3.3),“before”the words are“inserted”into syntactic structures. For example, the wordfortunately
is composed in the lexicon by a lexical rule that converts adjectives into adverbs by adding -lyto them; the word
enjoymentis composed in the lexicon by a lexical rule that converts verbs into nouns by adding -mentto them.
However, this treatment neglects an important distinction among word-building rules, between what I will call
productiveandsemiproductivelexical rules. Let us look at these types in turn.
6.2.1 Productive morphology
Productive morphology is totally regular, except where irregular forms block or supplant regular forms through the
“meta-constraint”of morphological blocking discussed in section 3.2.3. A prototypical case is the English present
participle(-ing) form, whichapplieswithout exceptiontoalltheverbsofthelanguage. TheEnglishpast tenseaffix-dis
similarly productive (given the predictable phonetic alternations between /-d/, /-t/, and /-əd/), except that it is
supplanted (blocked) by irregular forms in about 180 verbs.
Productive morphology is not confined to inflectional morphology (i.e. affixes like agreement, tense, and case); it
appears also in derivational morphology. For example, just about any English adjective can be converted into an
adverbbyadding -ly, asidefro m marked exceptionssuchasgood–well, fast–fastand adjectivesthat alreadyend in -lysuch
asfriendly. Similarly, the prefixpre- can be added freely to nouns that denote time periods or events, forming adjectives
such aspre-season, pre-summer, pre-game, pre-puberty, andpre-rehearsal.
In patterns of productive morphology, speakers confronted with a new base for mknow exactly how to for mthe
derived form and exactly what it means, as seen in the much-cited experiment of Berko (1958):
(1) Experimenter:This funny little thing is a wug. Now there are two of them. There are two...
Child:Wugs.Berko shows that by the age offive or so children have mastered the regular plural ending of English and can apply it
to nonsense words likewugthat they have never heard before. Moreover, speakers often create and encounter new
regular forms, without noticing they are doing anything special. For instance, Dutch speakers affix the productive
diminutive suffix-jeto every noun in sight.