Despite the agglutinative tendency encountered in the grammars of Toba and Pilagá (both Guaykuruan languages), verbs do not exhibit tense and mood categories. We argue that "irrealis" is signaled by the 'distal' markers ga' in Pilagá and ka in Toba. We show that signaling is at the pragmatic level of coding, and not yet at the syntactic level. 'Distal' deictics occur attached to demonstratives and proforms, nouns, and interrogative words in declarative and nondeclarative speech acts. They apply to any nominal participant perceived as 'absent' or 'unknown'. From the stance of both the speaker and the hearer, ga' and ka may pragmatically code that the event in question has not been realized, is hypothetical, or is a future projection. In addition, we hypothesize a diachronic path for development of negative existential constructions in these languages and a possible relationship between the 'distal' markers, "negation," and "irrealis."