This thesis is an analysis of Sextus Empiricus’ Against the Grammarians – a skeptical treatise on language written almost twenty centuries ago. In addressing this important chapter in the history of linguistic ideas, the study aims more broadly at the understanding of the relationship between language and skepticism. It is thus specially responsive to a contemporary scenario, where the virtues of language to promote understanding and communication are systematically placed under suspicion – in the arts in general, as well as in a significant part of the theoretical reflections in human and social sciences. Assuming that the examination of one of the remotest manifestations of skeptical thought about language may help understanding this contemporary scenario, this research was guided by the following questions: (i) what perspective(s) on language inform(s) Sextus Empiricus’s arguments in Against the Grammarians?; and (ii) what aspects of language fall under skeptical doubt in this treatise? The ancient text was thus interrogated by means of a deliberately anachronic strategy: our analysis took contemporary perspectives of language as points of reference - views that inflamed philosophical debate after the so-called linguistic turn, and can roughly be distributed between a pragmatic and a representationalist perspective. Since the dispute assumes quite different inflections according to the authors one has in mind, we have opted to focus on the manifestation of this debate within the philosophy of L. Wittgenstein, notably by taking as references the opposing voices that come into dialogue in his Philosophical Investigations. A first conclusion of this study is that two proto-images of language coexist within the argumentative web of Against he Grammarians, views that parallel the representationalist and the pragmatic contemporary stances. Another conclusion is that, in this ancient treatise, skeptical doubt falls over the idea that language has an intrinsic order, but not over language’s practical and day-to-day virtues.