After several years of loud and clear rejection, the idea of a public cognitive deficit insistently reappears in the agenda of Science Communication and Public Understanding of Science studies. This essay addresses two different kinds of reason - practical and epistemic - converging at that point. In the first part, it will be argued that the hypothesis of the lack of knowledge among laypeople and its controversial relationships with their interests and attitudes towards science prevails because it is an intuitive and optimistic way to frame the gap between science and society and, therefore, to cope with its causes and consequences. In the second part, a deeper level of reasons will be examined, in order to show that the persistence of the idea has its roots in the objective epistemic asymmetry between scientists and the public, the scope of which is not always properly judged. To recognize this asymmetry as a previous condition for their interactions may help to surpass the byzantine debate: deficit yes or no and open up original questions for the field, summarized in the closing remarks.