The problem of demarcation may take on many forms. A philosopher may ask what is typical of “true knowledge”, or whether science provides it, and if it does, what the reasons are. Thus he faces a demanding task of specifying the particularity of science as such because he has to find necessary as well as sufficient conditions of distinguishing between science and non-science. Add the urge to distinguish between meaningful and meaningless language expressions, and you get the ambition typical for the 20th century logical empiricism. The primary aim of the paper is to sum up a critical rationalist’s criticisms of demarcation criteria proposed by logical empiricism. The secondary aim is to link the criticisms, which are roughly known in our country, with the better known opinions of W. V. Quine and D. Davidson on three dogmas of empiricism.