IGCSE WJEC Politics: Formula & Theorem Rapid Reference Handbook | IGCSE WJEC 政治：公式定理速查手册

📚 IGCSE WJEC Politics: Formula & Theorem Rapid Reference Handbook | IGCSE WJEC 政治：公式定理速查手册

In IGCSE WJEC Politics, you do not use mathematical formulas in the same way as in physics or chemistry, but the subject is full of recurring ‘laws’, ‘theorems’ and models that explain how power, elections and institutions behave. This rapid reference handbook condenses the most important political ‘formulas’ into one revision-ready guide. Each entry states the core idea, a simplified expression where possible, and a WJEC-style example to help you apply it in exam answers.

在 IGCSE WJEC 政治中，虽然不像物理或化学那样使用数学公式，但课程中充满了反复出现的 “定律” “定理” 和模型，用以解释权力、选举和制度如何运作。本速查手册将最重要的政治 “公式” 浓缩为一份便于复习的指南。每一条目都给出核心观点、尽可能简化的表达式，以及 WJEC 风格的示例，帮助你在考试答案中加以应用。

1. Duverger’s Law | 迪韦尔热定律

Duverger’s law states that single-member plurality electoral systems tend to produce two-party competition, while proportional representation tends to produce multi-party systems. The ‘formula’ is a probabilistic tendency, not an iron rule, because it depends on social cleavages and regional parties.

迪韦尔热定律指出，单议席简单多数选举制度倾向于产生两党竞争，而比例代表制倾向于产生多党制。这个 “公式” 是一种概率性趋势，而不是铁律，因为它还取决于社会分歧和地区性政党。

Single-member plurality + winner-take-all → two-party competition

For WJEC, apply this to the UK Westminster Parliament, where First Past the Post has historically favoured Labour and Conservative dominance, while the Welsh Senedd’s Additional Member System allows parties such as Plaid Cymru and the Liberal Democrats to win more seats.

在 WJEC 考试中，可以将这一定律应用于英国威斯敏斯特议会：简单多数制历来有利于工党和保守党占据主导地位，而威尔士议会的附加成员制使威尔士党和自由民主党等政党能够赢得更多席位。

2. Median Voter Theorem | 中间选民定理

The median voter theorem predicts that in a two-party majoritarian election, parties will move their policies towards the centre to capture the median voter, because that is where the majority of votes are located.

中间选民定理预测，在两党多数决选举中，政党会将政策向中间靠拢，以争取中间选民，因为多数选票都集中在那里。

Party policy → median voter position (for maximum votes)

In practice, parties also face pressure from activists and core supporters, so they rarely become identical. The theorem helps explain why major UK parties often sound similar on economic competence, law and order, and public services during election campaigns.

在实践中，政党还面临来自活动人士和核心支持者的压力，因此它们很少变得完全一致。该定理有助于解释为什么英国主要政党在竞选期间往往在经济能力、法律与秩序以及公共服务方面口径相似。

3. Separation of Powers | 权力分立定理

The separation of powers theorem states that liberty is best protected when the legislative, executive and judicial functions are placed in different hands. If one person or body controls all three, power becomes arbitrary and dangerous.

权力分立定理认为，当立法、行政和司法职能由不同的人或机构掌握时，自由才能得到最好的保护。如果一个人或机构控制全部三项权力，权力就会变得专断而危险。

Liberty ↑ when Legislative ≠ Executive ≠ Judiciary

In the UK, the executive is drawn from Parliament, so there is a partial fusion of powers, but judicial independence has been strengthened by the Constitutional Reform Act 2005 and the creation of the Supreme Court. Comparing the UK with the US presidential system is a common WJEC essay task.

在英国，行政机关产生自议会，因此存在部分权力融合，但《2005年宪法改革法》和最高法院的设立加强了司法独立。比较英国与美国总统制是 WJEC 常见的论文题目。

4. Checks and Balances | 制衡公式

Checks and balances are the mechanisms that allow each branch of government to limit the power of the others. The formula is not a physical equation but a set of institutional veto points and scrutiny procedures.

制衡是允许政府各部门限制其他部门权力的机制。这个公式不是物理方程，而是一套制度性的否决点和审查程序。

Power A ↔ Power B ↔ Power C, each with veto or scrutiny over the others

Examples include parliamentary questions, select committee inquiries, votes of no confidence, judicial review, and the power of the House of Lords to delay legislation. These checks prevent any single institution from acting without accountability.

例子包括议会质询、

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