IB Diploma Programme Global Politics SL (first assessment 2019; 2016 guide). The core is shared by SL and HL, and this topic covers its opening unit in full — UNDERSTANDING POWER AND GLOBAL POLITICS — from the nature of power through sovereignty, legitimacy and interdependence to the source-analysis craft the papers demand. The course's key concepts (POWER, SOVEREIGNTY, LEGITIMACY, INTERDEPENDENCE) frame every answer, and the worked examples are original and reconciled.

Must-know for the core unit:

Power 权力 is the ability to influence outcomes and the behaviour of others — fundamentally RELATIONAL (A has power only over B, in a context), and visible as three FACES: the power to decide (visible), the power to set the agenda (hidden), and the power to shape preferences so the agenda is never questioned (invisible). Hard power 硬实力 compels — military force, sanctions, economic leverage; Soft power 软实力 co-opts — culture, values, the attraction of a model (the concept's coiner counted a country's universities, brands and media among its instruments); SMART power is the deliberate blend. The unit's key move is measuring power AS SITUATED: the US commands the hardest arsenal and the largest soft-power machine, yet could not prevent allies from defecting on specific votes — power is capacity in a context, not a score.

Sovereignty 主权 is supreme authority within a territory — the Westphalian settlement's principle (1648) that no outside authority overrides the state inside its borders. Its components: INTERNAL sovereignty (the state's monopoly of law inside), EXTERNAL sovereignty (recognition by other states), WESTPHALIAN sovereignty (non-intervention). The challenges: FROM ABOVE — global institutions and treaties binding states (trade rules, climate commitments, human- rights courts); FROM BELOW — separatist movements and non-state actors claiming authority inside; FROM WITHIN — failed states whose sovereignty is nominal. Sovereignty is bundled, not binary: states pool it (the EU), lease it (bases treaties) and lose it (sanctions regimes) by degrees.

Legitimacy 合法性 is the recognition that makes authority rightful (the difference between power and AUTHORITY. WEBER's three types still frame the field: TRADITIONAL (custom, monarchy), CHARISMATIC (the leader's personal bond) and LEGAL-RATIONAL (rules and offices, the modern state). Legitimacy rests on consent and is TESTED by performance: regimes delivering prosperity and security keep it, regimes failing amid corruption and inflation lose it — and illegitimate power must pay the hard-power price to stay (the authoritarian's dilemma). Internationally, legitimacy flows from recognition, treaties and institutions: a UNSC mandate converts an intervention from violation to enforcement in world opinion.

Interdependence 相互依存 is mutual dependence: states' outcomes are linked by trade, finance, security alliances and the shared environment — symmetric when dependence is mutual and balanced, asymmetric when one side can bear the relationship's rupture more cheaply (the leverage of sanctions). Interdependence creates both incentives for cooperation (the costs of conflict rise) and vulnerabilities weaponised in rivalry — chokepoints, dollar clearing, chip supply: dependence is power politics by other means.

The papers test source analysis 来源分析: identify the CLAIM (what the source asserts), the EVIDENCE offered (data, example, authority), and the PERSPECTIVE (who speaks, from what position, with what interest) — then weigh how the perspective shapes the claim. The toolkit is the history student's OPVL adapted: origin and purpose explain the source's angle; value and limitation are RELATIVE TO THE QUESTION — an official communiqué is limited on motives and excellent on the position a government wanted recorded. A political source's SILENCES — what it does not mention — are evidence too. For the stimulus-based papers, every answer ties concept to case: define power, sovereignty or legitimacy in a sentence, then apply it to the case's named actors and institutions, and weigh the counter-view — the same argue-weigh-judge spine as every essay in this course.

Worked example. A stimulus reports that a mid-sized state defied a great power's sanctions threat and signed a regional trade initiative anyway. The analysis writes itself in the unit's terms: the initiative's banks and market gave the mid-sized state an asymmetric-interdependence hedge (it could bear the rupture more cheaply than the threatener assumed); the great power's hard power was real but its agenda-setting (second-face) power failed because the regional institution had already reframed defection as sovereignty asserted, not defiance — legitimacy, not capability, decided the outcome.

• Power defined relationally; the three faces; hard/soft/smart with one example each (power).
• Sovereignty's four components (internal, external, Westphalian, and the bundling insight); the three challenge directions with a named case each (sovereignty).
• Weber's three legitimacy types; consent and the performance test; the authoritarian dilemma; international legitimacy via recognition and institutions (legitimacy).
• Interdependence: symmetric vs asymmetric; dependence as leverage; chokepoints and clearing as power politics (interdependence).
• Claim, evidence, perspective on any source; silences as evidence; concept-to-case tie in every answer (sources).

Boundary notes: the stimulus papers reward CONCEPT-CASE discipline — a definition, the named actors, the weighing of a counter-view — and the essay's top band demands synthesis across perspectives. All worked examples are original; the classic study facts cited are the standard record.