Introduction

This chapter focuses on the participation of unaccusative verbs in the causative–anticausative alternation as a testing ground for the Markedness Differential Hypothesis (MDH). It is argued that the MDH is inadequate and imprecise as an explanatory tool not only for diathesis alternations but also for other language elements which cause learning difficulty in second language acquisition (SLA). I begin with a review of the main claims of the MDH, followed by criticisms it has received in the literature. Later, I turn to the transitivity alternations of unaccusative verbs and discuss reasons why markedness cannot capture the problem of learning difficulty in the acquisition of the structures in question. The paper closes with a discussion of an unusual instantiation of the alternation in Polish involving double inchoative forms of unaccusative verbs, whose seemingly idiosyncratic nature resists explanation by the MDH and requires a more detailed descriptive approach to account for its complexity. I will attempt to show that far from being exposed by markedness, learning difficulty resides in the mastery of morphological marks which cue the selection of the structures involving unaccusative verbs.

Markedness as an explanatory tool

The MDH proposes to account for relative learning difficulty in terms of typological markedness of target language forms. The MDH states that ‘areas of the target language which differ from the native language and are more marked than the native language will be difficult’ (Eckman, 1977: 321). Although it is mainly invoked to explain the acquisition of elements of phonology, markedness has been successfully applied ‘to virtually all kinds of linguistic expressions, including [...] lexical, morphological, and syntactic structures, in a number of sub-domains of linguistics’ (Eckman, 2008). One of the undeniable advantages of the MDH is that it identifies areas of learning difficulty with more precision than its predecessor, the Contrastive Analysis Hypothesis (CAH) proposed by Lado (1957).