The main aim of the school1 sometimes called logical positivism, and later rather called neo-positivism, was without doubt to free philosophy from metaphysics. It is all the more astonishing to find that neither the definition nor the historical investigation of the concept "metaphysics' has ever been undertaken seriously in this school. Ayer for instance, in his famous anti-metaphysical work, "Language, Truth, and Logic",² says, " We are not now concerned with the historical question how much of what has traditionally passed for philosophy is actually metaphysical. " What must be noticed here is that his lack of interest in this historical question is an essential and fundamental trait of this school rather than a temporal reservation. But I wonder what significance there is in denying metaphysics without giving an explicit definition to the term " metaphysics. " Although Ayer stated in that context that he would offer a definition later, this promise has, to all appearances, not been fulfilled. If, however, this definition may be suggested in such sentences as "We may accordingly define a metaphysical sentence as a sentence which purports to express a genuine proposition, but does, in fact, express neither a tautology nor an empirical hypothesis",³ or " Being metaphysical, it is neither true nor false but literally senseless,"¹ we must conclude that this is neither a definition, nor an empirical summary, but a sheer slander of metaphysics.²