IB Philosophy 1.5.2 the Nature Versus Nurture Debate Notes

Framing the Debate

1. Topic 1.5.1 examined whether there is such a thing as human nature and whether that nature is flawed or perfectible.
2. This topic narrows the question further: to what extent are our characteristics fixed by biology, and to what extent are they shaped by environment? The nature versus nurture debate is one of the oldest and most consequential questions in philosophy.
3. The IB syllabus frames this topic around a single central question: "How fixed or malleable is human nature?" This question asks whether the traits we associate with being human (intelligence, temperament, moral character, language) are biologically determined or environmentally shaped, and whether the answer differs depending on which trait we examine.
4. On the nature side of the debate, nativists (philosophers who argue that the mind comes pre-equipped with certain ideas or abilities) argue that many human characteristics are innate: built into us by our genes, not learned from experience. This view has roots in Plato, who argued in the Meno that knowledge is not learned but 'recalled' from before we were born, suggesting the mind already contains certain knowledge from the start.
5. In the Meno, Socrates demonstrates this by questioning an uneducated slave boy about geometry. Through a series of carefully directed questions (without providing any answers), the boy arrives at the correct solution to a problem about doubling the area of a square.
6. Plato concludes that the boy must have possessed this knowledge before birth and was merely 'recollecting' it, evidence that at least some knowledge is innate rather than learned.
7. John Locke's tabula rasa thesis (discussed in 1.5.1) holds that if the mind starts as a blank slate, then all differences between people must come from their experiences. This has major implications for education and social policy: inequality between groups would reflect unequal environments, not innate differences, and the right conditions could in principle change anyone's development.
8. B.F. Skinner's behaviourism (introduced fully in 1.5.1) represents the most radical nurture position, arguing that all human behaviour, including language, morality, and emotion, is the product of environmental conditioning through reinforcement and punishment.
9. Skinner's behaviourism was challenged by Noam Chomsky, whose devastating 1959 review of Skinner's Verbal Behavior argued that language acquisition cannot be explained by conditioning alone.
10. Chomsky showed that children produce sentences they have never heard, suggesting an innate language acquisition device (a built-in capacity for learning language) wired into the brain from birth. This argument against Skinner's view seriously weakened the case that environment alone can explain human development.
11. The debate is not merely academic: it shapes how societies respond to social problems.
12. If criminal behaviour is innate, then punishment or genetic intervention seems appropriate; if it is environmentally caused, then social reform is the proper response.
13. The nature-nurture question therefore connects directly to moral responsibility (1.4.3) and to social conditioning (1.6.2).
14. The nature-nurture debate has historically been politically charged: claims about innate racial or gender differences have been used to justify discrimination and oppression.
15. Philosophers must therefore approach this debate with both intellectual rigour and ethical sensitivity, examining the evidence carefully while being alert to the political uses of scientific claims.
16. The overarching Unit 1 question, "What does it mean to be human?", takes on particular urgency in the nature-nurture debate.
17. If human nature is highly malleable, what it means to be human may vary enormously across cultures; if it is relatively fixed, then there are universal constraints on what human beings can become, regardless of their environment.