The adjacent Layer-I papers (I3.1 major-selection, I3.2 labour-market, I3.3 family integration) each presuppose a meta-skill that the chooser is rarely taught explicitly: how to make a decision under genuine uncertainty when expectedvalue optimisation is not available. This paper synthesises the decision-research literature to provide that meta-skill foundation for Vietnamese learners aged 14–19. Three structurally different decision regimes are distinguished — risk (probabilities approximately known; expected-value optimisation is sound), uncertainty (probabilities unknown; heuristics plus reversibility-aware framing dominate), and genuine ignorance (no model of outcomes; option-creating and minimum-regret are the only defensible moves) — following Knight 1921 and the modern reception of his risk-uncertainty distinction 1, 2. The paper presents the Kahneman-Gigerenzer dialectic honestly: Kahneman 2011 and the Tversky-Kahneman 1979 prospect-theory programme established the heuristics-and-biases tradition that dominates popular discourse 3, 4, 5, while Gigerenzer 2007 / 2008 and Klein 1998 / 2008 documented that fast-and-frugal heuristics frequently outperform optimisation under realistic information conditions 6, 7, 8, 9, 10. The replication-crisis evidence is presented without sanitisation: a meaningful fraction of the popularised everyone is biased canon has weakened or failed replication 11, 12, 13, 14, and guidance content built on the strong form of the canon is inheriting an over-claim. Adolescent-specific findings from Reyna-Farley 2006 and Steinberg 2007 / 2008 establish that adolescent decision-making is a developmentally distinct mode in which the gist-versus-verbatim balance and the reward-sensitivity / cognitive-control gap are load-bearing 15, 16, 17, 18. The cross-cultural evidence 19, 20 places Vietnamese adolescents in a high uncertaintyavoidance, collectivist-leaning context that systematically modifies how the Anglo-American decision-research prescriptions transfer. The paper's central operational contribution is a reversibility-aware framing — irreversible / partially-reversible / reversible — argued to be the load-bearing axis for an adolescent without strong probability calibration. The deliverable is a ranked operational skill set of ten practices ranked by evidence strength, deployability without instruments, and Vietnamesecontext fit. Worked examples cover major-selection, romanticpartner choice, financial decisions, opportunity acceptance, and relationship termination. Per the elix-researches no-cohort scope 21, no empirical validation with Vietnamese adolescents is in plan.
That Le (Tue,) studied this question.