Continuum fallacy

The continuum fallacy is when you say that because there's no sharp line between two things (e.g. when a heap of sand stops being a heap), the distinction doesn't exist or we can't use it. Not being able to draw a precise boundary doesn't mean there's no difference. We often make useful distinctions even when boundaries are fuzzy. The fallacy is to demand a sharp line and then, when we can't give one, to conclude the distinction is invalid. Many useful concepts have vague boundaries.

Examples

• You can't say when life begins—there's no exact moment—so we can't treat early and late differently.

• There's no exact line between tall and short, so "tall" is meaningless.

• We can't define "child" precisely, so we can't have different rules for children.

• There's no precise moment when night becomes day, so we can't distinguish night and day.

• "Rich" and "poor" have no sharp line, so we can't tax the rich.