A fundamental part of the answer to the question of what is language is the answer to the controversial question of what is linguistic variation. In the first part of this lecture I will review the old and often revisited notion of variation. I will mainly focus on the relevance of the view that variation is linked to (syntactic macro) “parameters” and “microparameters” of UG vs. the idea that variation is more related to “externalization” factors and to the crucial notion of interface, thus giving rise to the possibility of connection between formal approaches to linguistic variation and other non-formal approaches to this topic. In the second part of this lecture, relying on research carried out with Prof. Olga Fernández-Soriano. I will briefly present an analysis of the Spanish evidential dizque that we consider as a true evidential modal operator. We claim that in this case variation relies on the so called ‘dichotomy’ view of evidentials according to which languages may vary crosslinguistically and in dialectal variation with respect to the semantic type of evidentials they allow. I will suggest that a specific evidential can be described as an epistemic modal in a vast area of Spanish whereas in some variants the same element appears to be an illocutionary marker. The point of departure for the proposed account is the syntax/semantics-pragmatics interface.