Bobaljik (2012) shows that patterns of suppletion can be used as a diagnostic of morphological structure. Specifically, we can see evidence that certain heads are located inside other heads in complex categories. Bobaljik shows this with a thorough study into suppletion patterns in adjective-comparative-superlative triples, showing that the comparative is universally contained within the superlative as in (1), below (see section 2 for further details). In this paper, we present the results of a survey into pronominal suppletion patterns found with case and number, and show that cross-linguistically robust patterns provide evidence for each category being internally complex.

For case, following the same logic as in Bobaljik (2012), we argue that the representation of oblique cases contains the representation of the ‘dependent’cases (in the sense of Marantz 1991, ie accusative and ergative), and the dependent cases in turn contain the unmarked (nominative, absolutive) cases (cf. Caha 2009). In other words, we may represent the relation among cases on a pronominal base as in (2), paralleling Bobaljik’s proposal for adjectival gradation in (1): 1