Convention (norm)

A convention is a set of agreed, stipulated or generally accepted rules, norms, standards or criteria, often taking the form of a custom.

Certain types of rules or customs may become law, and regulatory legislation may be introduced to formalise or enforce the convention (eg. laws which determine which side of the road vehicles must be driven). In a social context, a convention may retain the character of an "unwritten" law of custom (eg. the manner in which people greet each other, such as by shaking each other's hands).

In physical sciences, numerical values (such as constants, quantities, or scales of measurement) are called conventional if they do not represent a measured property of nature, but originate in a convention, for example an average of many measurements, agreed between the scientists working with these values.

General
A convention is a rule or a selection from among two or more alternatives, where the rule or alternative is agreed upon among participants. Often the word refers to unwritten customs shared throughout a community. For instance, it is conventional in many societies that strangers being introduced shake hands. Some conventions are explicitly legislated; for example, it is conventional in America and Germany that motorists drive on the right side of the road, whereas in England and Barbados they drive on the left. The extent to which justice is conventional (as opposed to natural or objective) is historically an important debate among philosophers.

The nature of conventions has raised long-lasting philosophical discussion. Quine, Davidson and David Lewis published influential writings on the subject. Lewis's account of convention received an extended critique in Margaret Gilbert's On Social Facts. Another view of convention comes from Ruth Millikan's Language: A Biological Model (2005), once more against Lewis.

Customary or social conventions
In every field of art, science, or other human endeavor, there are conventions that may simply be expectations (strangers being introduced shake hands, paintings are rectangular) or stock devices (a comedy ends with a marriage, but a cowboy film can end with the hero riding off into the sunset). There are generic conventions which are very closely tied to a particular artistic genre, and may even help to define what that genre is. Terms such as fan conventions and science fiction conventions could be interpreted in this manner, but more often refer to the meaning of "convention" as a gathering or the physical location of a gathering.

Government
In government, convention is a set of unwritten rules which the participants in the government are expected to follow. These rules can be ignored only if justification is clear, or can be provided. Otherwise, consequences are sure to follow. Consequences may include ignoring some other convention that has until now been followed. According to the traditional doctrine (Dicey), conventions cannot be enforced in courts, because they are non-legal sets of rules. Convention is particularly important in the United Kingdom and other governments using the Westminster System of government (e g Canada and Australia) where many of the rules of government are unwritten.

International law
The term convention is also used in international law to refer to certain formal statements of principle such as the Convention on the Rights of the Child. Conventions are adopted by international bodies such as the International Labour Organization and the United Nations. Conventions so adopted usually apply only to countries that ratify them, and do not automatically apply to member states of such bodies. These conventions are generally seen as having the force of international treaties for the ratifying countries.