It's rational to remain ignorant when the cost of education exceeds expected benefit.
Downs's 1957 argument. One vote almost never decides an election, so the cost of becoming informed exceeds the expected benefit — which makes ignorance rational and democratic competence a collective problem.
In practice
- A voter who would need four evenings to compare two manifestos spends those evenings otherwise, and votes anyway.
- A shareholder with 0.001% of a company rationally does not read the annual report, and the aggregate of that rationality is an unmonitored board.