Step 1: Realist Tradition Overview.
In political realism, the key guide to statecraft is National Interest, which emphasizes the importance of a state's power, security, and survival in the international system.
Step 2: Analysis of options.
- (A) National Interest: Realist theory emphasizes that a state's actions are driven primarily by its national interest, which revolves around survival, security, and economic power.
- (B) Universal brotherhood: This concept aligns more with idealism and does not fit within the realist tradition, which is more pragmatic and focused on self-interest.
- (C) Moral Principles: While moral considerations may influence policy, realism is largely based on pragmatic considerations rather than moral principles.
- (D) Cross-border flows and common values: This focuses on cooperation and shared values, which are more aligned with liberal theories rather than the realist approach.
Step 3: Conclusion.
The correct answer is (A) National Interest, as realism prioritizes the national interest as the fundamental driver of state actions.