Kinds of morphological generalisation

There are several kinds of morphological generalisation which need expression in a theory of morphology.

1. Construction generalisations: According to what principles are words constructed?
   1. The ID hierarchy defines the stratification of linguistic units (morphemes, ... , words, ... , sentences, ...). This stratification is sometimes known as a rank scale.
   2. The QLP hierarchy (known in phonology as the Prosodic Hierarchy) defines the hierarchical structure of temporal relations (in speech and the production of writing) and spatial relations (in written inscriptions).

   These construction generalisations correspond to syntagmatic relations, in traditional linguistic terminology: they are concerned with part-whole relations in and between linguistic units.

2. Class generalisations: How can linguistic units (in particular words) be classified according to similarities in distribution and constituency, and in phonetic and semantic interpretation?

   The class generalisations correspond to paradigmatic relations, in traditional linguistic terminology: they are concerned with similarity relations between, shared properties of, or fields of linguistic units. If words share the same syntagmatic relations, then these syntagmatic relations form the basis of a paradigmatic relation.