‘Convention’ explores the role of conventions in games and society. Conventions may be entirely arbitrary, but are extremely important in society. Humans will invent conventions in situations where no obvious ones exist. Convention is essential in fields such as traffic management, but philosophers such as Hume have courted controversy by suggesting that conventions exist in ethical reasoning as well. Game theory is by nature devoid of ‘values’, and can only point out faulty reasoning. Social dilemmas occur when trying to match individual goals with the common good. Game theory provides a framework for discussion. Selfish actions are always possible in social situations, and trust can be difficult to rely on.