This thesis investigates epistemic indefinites (EIs), elements noteworthy for their /ngrammaticalized ignorance implicature, i.e. inability to provide further information about /nthe identity of the expression's referent. This work contributes to the effort of finding /na unified account of the cross-linguistic repertoire of EIs. It comprises a corpus survey /nand a semantic analysis of Slovak voľa- and -si, EI items not studied until now. First, /nthe following hypothesis was tested: the semantic/syntactic functions expressed by an /nindefinite will fall into contiguous areas on an implicational map (Haspelmath 1997). /nThe results of the corpus analysis revealed that the map does not entirely capture the /nSlovak EIs' functional distribution and interpretations. Secondly, the semantic analysis /nwas developed within the alternatives-and-exhaustification framework (Chierchia 2013). /nI show that some of the EIs' behavior can be explained as a consequence of an assumed /nsensitivity to parameters proposed by Chierchia. I situate voľa- and -si with respect to the /nframework’s typology and offer a critical assessment of this theoretical perspective.