This book emphasizes the comparative study of theoretical as well as hypothetical issues of structural realism of international relations theory vis-Ã-vis those of systemic geopolitical analysis. Are they scientific fields evolved in parallel, common philosophical and cognitive roots? Could they be used as complementary theoretical tools or their relation is disjunctive and contrapuntal? When decoding the core hypotheses of structural realism and systemic geopolitical analysis, an effort takes place for the sake of the central scientific aim; i.e. the untainted descriptive analysis without ontologically groundless claims. The debate on interstate relations and the framework, on which these are structured, is long-term with its philosophical background detected at the juxtaposition between those referring to "sein" and the others expressing the "sollen". This research struggles to explain the converging and diverging points of view between the neorealist approach of international relations theory and the systemic geopolitical analysis.