Being human · Arguments, identity and personhood

IB Diploma Programme Philosophy SL (the guide first assessed in 2024). This topic covers the core theme 核心主题, being human, which every SL and HL student studies. It is examined in Section A of Paper 1, where you answer one question on a stimulus 材料 (a short text or an image) by finding a philosophical issue in it and discussing it. Paper 1 lasts 1 hour 45 minutes at SL (50%) and 2 hours 30 minutes at HL (40%); the rest of the paper is essays on the optional themes (topic 02). The core theme's ideas (identity, personhood, freedom, mind) appear in every other part of the course.

In September 1848 an explosion drove an iron rod through the head of Phineas Gage, a railway worker in Vermont. Amazingly, he survived and could walk and talk. But his doctor reported that his friends said he was "no longer Gage": the polite, careful worker had become rude and unreliable. Was he still the same person? If his character changed because his brain changed, is a person just a brain? Could he be blamed for his new behaviour? These are the questions of being human.

Must-know for the core theme:

Philosophy 哲学 works by argument 论证: reasons, called premises 前提, that support a conclusion 结论.

• An argument is valid 有效的 if the conclusion must be true when the premises are true. Validity is about form only.
• An argument is sound 可靠的 if it is valid and its premises are actually true.
• Deductive 演绎的 arguments aim at certainty; inductive 归纳的 arguments move from many cases to a probable conclusion.

Common fallacies 谬误 (errors in reasoning):

Philosophers also use thought experiments 思想实验: imagined cases that test a concept. Read each one twice: once for what it shows, and once for what it assumes.

Worked example. "Every event has a cause. My choices are events. So I am not free." The argument needs a hidden premise: "caused choices are not free". That premise is exactly what compatibilists deny, so the argument does not prove its conclusion against them.

The inference to 'not free' needs a hidden premise, and that premise is what is in dispute

Personal identity 人格同一性 asks what makes you the same person as the child in your old photographs.

Reid's case shows that memory alone fails: identity must carry over (if A = B and B = C, then A = C), but memory does not. Parfit answers that what matters is not strict identity but continuity, which can come in degrees, as Phineas Gage's story suggests.

Personhood 人格 is a moral idea, not a biological one. A human 人类 is a member of our species; a person 人 is a being with certain abilities: consciousness, reason, self-awareness, communication, moral responsibility. The two groups may not match exactly. Some philosophers argue that great apes or future AI might be persons; others ask whether newborn babies or people in a coma meet the criteria. This is why personhood matters in debates on abortion, the end of life, animal rights and artificial intelligence.

The free will 自由意志 problem: if every event has a cause, can any choice be free?

The three positions answer two different questions: is determinism true, and could free will exist if it were?

Harry Frankfurt's "unwilling addict" helps the compatibilist: the addict takes the drug, but wishes he did not want it. He is unfree not because his act was caused, but because he acts on a desire he rejects. Freedom, on this view, means acting on desires you accept.

Dualism 二元论 (associated with René Descartes) says the mind is different from the body: thoughts and feelings are not physical things. Physicalism 物理主义 says everything, including the mind, is physical: a thought is a brain process.

• The knowledge argument 知识论证 (Frank Jackson): Mary is a scientist who knows every physical fact about colour but has lived all her life in a black-and-white room. When she first sees red, does she learn something new? If yes, not all facts are physical.
• Phineas Gage supports physicalism: damage to the brain changed the person.

1. Identify the philosophical issue 哲学问题 in the stimulus and link it to the core theme ("the stimulus raises the question of whether ...").
2. Explain two or three positions with named philosophers.
3. Evaluate: give the strongest objection to each and a reply.
4. Reach a clear conclusion that follows from your arguments.

Worked plan. Stimulus: a news report about a person whose personality changed after a brain injury.

• Issue: does personal identity depend on psychological continuity?
• Positions: the body theory (same person, same body); Parfit's psychological continuity (identity weakens as character changes).
• Objections: the body theory ignores what we care about in a person; Parfit's view makes identity vague.
• Conclusion: the case supports Parfit; the person is partly, not wholly, the same, and we should judge their new behaviour with care.

• Arguments: premises and conclusion; valid and sound; deduction and induction; four fallacies; thought experiments; hidden premises.
• Identity: body, memory and psychological continuity theories with their problem cases (Theseus, Reid's officer, the teleporter).
• Personhood: human versus person; why the idea matters ethically.
• Freedom: hard determinism, libertarianism, compatibilism, and Frankfurt's unwilling addict.
• Mind: dualism, physicalism, Jackson's knowledge argument.
• Section A: issue, positions, objections, conclusion.