4 A. Linear Stages Theory — "development as a ladder"

• Rostow's five stages (also your Sociology Unit 5): traditional society → preconditions for take-off → take-off → drive to maturity → age of high mass-consumption. Development = climbing the ladder; the constraint is capital.• Harrod–Domar model — the algebra of the same idea: growth rate g = s/v (savings ratio ÷ capital–output ratio). Raise savings (or make investment efficient) and growth follows; the rationale for aid ("fill the savings gap") and for infrastructure-first planning.• Critique: history is not a ladder all must climb in order; Rostow's take-off dates barely survive scrutiny; and savings are necessary, not sufficient — institutions, human capital and demand matter (China's g = s/v alone would have failed to predict 1978–2018).