The aim of this article is to analyse the kind of inference used in the reconstruction of proto-languages. Hypothesis is at the core of this reconstruction process and this, together with the structure of reasoning involved, indicates abductive reasoning. We analyse abductive reasoning, and specify its nuances and particularities. The novelty we introduce is the importance of context as we focus on a form of abduction that goes beyond the context in which the scientific work is being developed by incorporating (...) contexts from other sciences. Therefore, an intercontextual chain of inference can be part of abductive reasoning processes and the resulting hypothesis remains provisional. Several disciplines, such as archaeology, history and linguistics, play a cognitive role in the reconstruction of proto-languages, thus requiring more than one context. We use the case of the reconstruction of proto-Semitic and the unexpected fact of the Ugarit and Ebla discoveries (plus Amorite names). This sample may shed light on the use of abduction to explain certain scientific practices. (shrink)