A paradigm is an organization of related forms. But the organization is independent of any particular item or set of items that participate in the paradigm. To have a paradigm, a language must have two distinct "inventories": First, it must have a set of "syntactic features", such as [±tense], [1/2/3 person], [±plural]. These features define a matrix of "syntactic categories". Second, it must have a set of "morphological subcategories" (MSC) - that is, word-sets that are morphologically distinct from each other. Finally, there must be some relation between the matrix of syntactic categories and the MSCs - each syntactic category is filled from one of the MSCs.
- Williams (2004), Pag. 227