The diachronic development of modal verbs has been investigated in a number of works during the last few decades (Traugott 1989, Krug 2000, Fischer 2004, Hansen 2004, Traugott & Dasher 2005, Narrog 2012 and others). However, this research has been largely dominated by the study of Germanic languages: with the exception of some observations made by Holvoet (2007) and Jasionytė-Mikučionienė (2014), the realizations of modality in Lithuanian have not been thoroughly examined from the point of view of their historical development. Thus, the paper aims at filling this gap and providing a thorough account of the diachronic evolution of modal meanings of the two Lithuanian verbs reikėti ‘need' and turėti ‘have to' that function as one of the main means for expressing non-epistemic modality in Lithuanian.

The data for this research is drawn from corpora comprising texts of Old Lithuanian (16th-17th c.c.) and Modern Lithuanian.

In the analysed texts of Old Lithuanian, reikėti ‘need' and turėti ‘have to' predominantly convey participant-external and deontic necessity. However, in the earliest period of the language turėti ‘have to' already shows ambiguity between the meanings of participant-external and epistemic necessity, – it is hypothesized that participant-external necessity may be the basis for the development of the epistemic meaning (cf. the discussion on the issue in van der Auwera & Plungian 1998, Narrog 2012). In Modern Lithuanian, turėti ‘have to' has acquired potential to convey epistemic values, while reikėti ‘need' is less polyfunctional and mostly marks participant-external necessity. It is assumed that the types of the constructions the verbs appear in (personal vs impersonal) play a crucial role for the emergence of their modal meanings. The development of modal meanings of the verbs is analysed within the framework of subjectification proposed by Traugott (1989).