This book was written in 1968, and defended as a doctoral dissertation before the Philosophical Faculty at the University of Fribourg (Switzerland) in 1969. It treats of the systematic views of Hegel which led him to give to the princi­ ple of non-contradiction, the principle of double negation, and the principle of excluded middle, meanings which are difficult to understand. The reader will look in vain for the philosophical position of the author. A few words about the intentions which motivated the author to study and clarify Hegel's thought are therefore not out of place. In the early sixties, when occupying myself with the history of Marxist philosophy, I discovered that the representatives of the logical-positivist tra­ dition were not alone in employing a principle of demarcation; that those of the dialectical Marxist tradition were also using such a principle ('self-move­ ment') as a foundation of a scientific philosophy and as a means to delimit unscientific ideas. I aimed at a clear conception of this principle in order to be able to judge whether, and to what extent, it accords with the foundations of the analytical method. In this endeavor I encountered two problems: (1) What is to be understood by 'analytical method' cannot be ascertained un­ equivocally.