Optional themes; prescribed text · Ethical reasoning and textual interpretation

IB Diploma Programme Philosophy SL (the guide first assessed in 2024). Besides the core theme, schools choose optional themes 选修主题 from seven: aesthetics, epistemology, ethics, philosophy of religion, philosophy of science, political philosophy and social philosophy. SL students study one theme and HL students two. You write one essay on each theme in Section B of Paper 1. Every student also studies one prescribed text 指定文本 from the IB's list, examined in Paper 2 (1 hour; 25% at SL, 20% at HL).

A runaway train is heading towards five workers on the track. You can pull a lever and send it onto a side track, where it will kill one worker instead. Should you pull it? Most people say yes. Now imagine you are on a bridge, and the only way to stop the train is to push a large man onto the track. Most people say no, although the numbers are the same. The philosopher Philippa Foot described the first version in 1967, and it has been argued about ever since. Why do our answers change? Each ethical theory gives a different explanation.

Must-know for the themes and the text:

The trolley cases three ways. A utilitarian pulls the lever and pushes the man: five lives outweigh one. A Kantian may pull the lever (the death is a side effect) but not push (that uses the man only as a means). A virtue ethicist asks what a good person could live with, and may say that pushing someone to his death is something a decent person would not do. An essay that compares all three, and then judges which explains our intuitions best, shows the analysis examiners reward.

Epistemology 认识论 asks what knowledge is and how we get it. A traditional answer: knowledge 知识 is justified true belief 有理由的真信念. In 1963 Edmund Gettier showed cases where a person has a justified true belief that is true only by luck. A simple example (from Bertrand Russell): you look at a clock that says 3:00 and believe it is 3:00. It is 3:00, but the clock stopped exactly twelve hours ago. Your belief is true and justified, but is it knowledge?

A Section B essay discusses one question in depth:

1. Define the key terms and state your answer.
2. Explain two or three positions with named philosophers.
3. Test each with an example or thought experiment, and give the strongest objection.
4. Reach a conclusion that weighs the positions.

Read your text as an argument, not a story. Use four steps:

Worked example: John Stuart Mill, On Liberty (1859). If your school studies a different text, use the same four steps.

• Context: Victorian Britain; Mill feared that public opinion, not only governments, could crush individual freedom.
• Claim: the harm principle 伤害原则: "the only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others."
• Argument: free discussion helps us find the truth, because even a wrong opinion may contain part of the truth and forces us to defend our beliefs.
• Critique: what counts as "harm"? Offence, or harm to oneself (such as drug use), may also affect others. Mill can reply that he means clear harm to others' interests, but where to draw the line remains debated.

Each Paper 2 question has two parts: (a) explain an idea from the text (10 marks), then (b) evaluate or discuss it (15 marks). The IB's own examples include Plato's Republic and the Tao Te Ching 道德经.

Worked plan. A sample question from the IB: (a) Explain the view of the state found in the Tao Te Ching. (b) Evaluate the claim that the view of the state found in the Tao Te Ching assumes an overly positive view of human nature.

• (a) The best ruler acts through non-action 无为: he interferes as little as possible, so that people hardly notice him (chapter 17). More laws create more crime (chapter 57), and governing a large state is like cooking a small fish: stir it too much and it falls apart (chapter 60).
• (b) For the claim: the text seems to trust that people left alone will live simply and peacefully; Hobbes, who thought life without a strong state would be "nasty, brutish, and short", would disagree. Against the claim: the text does not say people are good, only that heavy government creates the desires and conflicts it then tries to control. Judgement: the view is less naive than it looks, but it fits small, simple communities better than large modern states.

• The seven optional themes; one at SL, two at HL; Paper 1 Section B.
• Ethics: the three theories with their problems; the trolley cases three ways.
• Epistemology: justified true belief; Gettier; the stopped clock; rationalism, empiricism, scepticism.
• The key question and two positions for each other theme.
• The theme essay plan.
• The prescribed text: context, claims, arguments, critique; Mill's harm principle as a worked example.
• Paper 2: (a) explain, 10 marks; (b) evaluate, 15 marks; the worked Tao Te Ching plan.