Convention: How Can a Human-Made Rule Create Real Constraints?

A convention is one option adopted together from several that could have worked, allowing people to anticipate one another's actions. Australian traffic keeps left because of convention, not because nature makes the left side intrinsically better. Yet once roads, vehicles and driving habits are organised around that choice, an individual who suddenly keeps right creates a real danger. The origin may be human, but the consequences are not imaginary.

A convention differs from a personal habit, which one person can maintain alone; convention depends on mutual expectations. It is not identical to law either. Some conventions are codified in law, while others persist through shared use. A standard often makes a convention more exact so that different organisations can repeat it reliably.

The concept prevents two mistakes. Human-made does not mean arbitrary and ineffective, while established does not mean impossible to revise. Changing a convention usually requires coordinated transition because the constraint lies not only in written rules, but also in the people and infrastructure already organised around them.