4 Common knowledge

‘Common knowledge’ refers to any piece of information that:

• is widely known within a specific discipline;
• may frequently be found in different academic sources, unreferenced;
• may be attributed to a number of different authors.

This brief definition should help you realise that common knowledge can be subject-specific: concepts and information that are widely known in environmental science, for example, may not be widely known in art history, and vice versa.

Common knowledge also depends on the level of study. If you are new to a subject area, you will have less knowledge and understanding about the topic than if you are an expert. The more experience you develop, the more your subject-specific language will develop – but, at the same time, you will also use more specific evidence from other people’s work to support your own work and ideas.

It should be evident that, in general, there is no need to provide a reference for a piece of factual information that is deemed to be common knowledge. However, deciding whether something is ‘common knowledge’ is a matter of academic judgement!

For example, the dates of the Second World War, the chemical symbol for water, pi to two decimal places or the current prime minister of the UK are all common knowledge in the UK. This is because:

• most people know these things;
• they are easy to verify by referring to a number of different, easily accessible sources (e.g. a dictionary, encyclopedia, asking friends, etc.).

Anything that has to be looked up in a specialist reference book or is attributable to a specific author would not count as common knowledge. You need to consider who you are writing for when you are deciding whether something is ‘common knowledge’ or not. If you are not sure whether something is or is not common knowledge, the best approach is to include a reference to the source where you found the information.