SUMMARY
The author treats the processes that lead to the establishment of a prehistorical dialect area, in other words, a connection between two or more proto-related languages in a known or unknown geographical territory. The dialectology of linguistic families must, as every inductive inquiry, frequently allow a certain degree of vagueness if it is to come to any conclusions. However, the discrepancy between a good and bad interpretation of linguistic material can be significant. This is demonstrated by the analysis of examples that linguists have adduced in support of a prehistorical ancient Balkan-Baltic-Slavic dialect areal. By examining the argumentation theory, the author reveals typical fallacies and questionable methods in the process of reaching conclusions. These are: 1) the attempt to interpret material from a poorly attested language (the linguistic laws are unknown, etymologies unverifiable); 2) comparison of roots (because of the small number of elements and the typically simple structures, there is high probability that the similarity is coincidental); 3) circular reasoning, in which the author explains a fact with an unproven premise; examples where the author is led to a decision among variant readings by a preferred outcome; 4) drawing equivalencies among various types of proper nouns and appellatives without consideration of the methodological problems surrounding them; 5) ignorance of facts concerning a linguistic phenomenon that exists outside of the areal under consideration, as well as failure to consider the full weight of the evidence; 6) uncritical appropriation of findings from other disciplines and the transfer of these findings to comparative linguistics; 7) the explanation of poorly attested material with further poorly attested material; 8) explanation failing to follow logically from the material. With the aid of some of the procedures adduced we can prove the existence of dialect areals that are known never to have existed in reality. Regardless of the fact that the dialectology of linguistic families has existed from the beginnings of comparative linguistic as its constitutive part, it is clear that the methodology of this field of inquiry has yet to be thought through completely. Many hasty and unacceptable conclusions can be avoided by keeping in mind the questionable procedures and fallacies in the discovery of dialect areals adduced in this article.