INTRODUCTION

The recurrent interchangeability or identity of conditional and interrogative markers has been noted in a number of unrelated languages, among them the members of the Uralic family (Beke 1919), Germanic, French and Greek (Havers 1931: 21) and Chinese (Chao 1968: 81–2). The phenomenon is explained on the assumption that conditional protases are the topics of the sentences in which they occur (Haiman 1978; for further discussion, see Akatsuka, Ford and Thompson in this volume). As topics constitute information whose validity is (perhaps only provisionally) agreed upon by all parties to the discourse, it is natural for a speaker to establish their given status by asking for assent or recognition from his interlocutor. In some languages, the semantic equivalence of protasis and topic is directly reflected by the identical morphology and syntax of these two categories: representative examples are Turkish (Lewis 1967: 217), Tagalog (Schachter 1976: 496), Tabasaran (Magometov 1965: 271), Korean (Martin and Lee 1969: 146, 159), Vietnamese (Hoa 1974: 103, 341), Middle Egyptian (Gardiner 1957: 125) and, once again, Chinese (Chao 1968: 81–110).