A model is a mental or formal representation of a system which is used to anticipate its future behaviour.
Modelling is a universal activity. All of us, scientists or not, construct models to help us understand the world around us and to guide our planning and decision-making. When we store information from the past and use it to predict the behaviour of the future, we are modelling.
Every living creature on the planet stores information from the past and from it extracts regularities. These regularities are a model of the environment which that creature uses to anticipate the future.
CSIRO ecosystems scientist Fabio Boschetti explains: ‘Whether it is a tree responding to shortening day length by dropping its leaves and preparing its metabolism for winter – in advance of winter – or a naked Pleistocene ape storing food in advance of winter for the same reasons, both are using models.’
In his 2008 address on social simulations at the Santa Fe Institute, Joshua Epstein elaborates: ‘Anyone who ventures a projection, or imagines how a social dynamic – an epidemic, war, or migration – would unfold is running some model…’When you close your eyes and imagine an epidemic spreading, or any other social dynamic, you are running some model or other. It is just an implicit model that you haven’t written down.’
There are a number of reasons to construct models, including:
- Prediction – To create predictive scenarios that allow us to prepare for the future;
- Understanding – To illuminate the workings of the system being modelled;
- Training – To teach skills and attitudes useful for dealing with complex systems.