The basic vocabulary argument has been used both in attempts to refute as in attempts to support the Altaic origins of the Japanese language.  Recent etymological studies of Japanese involving basic vocabulary reach contradictory conclusions.  Given this lack of consensus, the lecture deals with the concept of basic vocabulary and the ways in which it can throw light on the Altaic affiliation question for Japanese.  Advancing a more precise methodology, the Altaic etymologies proposed for Japanese basic vocabulary so far, are evaluated.  Sharing a certain amount a basic vocabulary is not a conditio sine qua non for the demonstration of common ancestorship.  The question that can be solved by applying a basic vocabulary test is whether the regular correspondences that relate Japanese to Altaic are more likely to be the result of common ancestorship or whether they are more likely to be the result of mass borrowing.