A model is an abstract representation of reality in some form (for example, mathematical, physical, symbolic, graphical, or descriptive), designed to capture certain aspects of that reality and to provide answers to the questions under study.
By "model" we mean a material or mentally conceived object that, in the process of investigation, stands in for the original object while preserving certain features that are essential to the given research. The process of constructing and using a model is called modeling.
A model is needed in order to:
- understand how a specific object is organized: its structure, internal relationships, fundamental properties, laws of development, self-development, and interaction with the environment;
- learn to control the object or process, and to determine the best methods of control given specified goals and criteria;
- forecast both direct and indirect consequences.
When speaking of scientific modeling, it is worth clarifying the meaning of the terms "model" and "theory." In contemporary scientific literature, these concepts are interpreted in various ways, and the boundary between them is blurred. The following interpretations are currently accepted in the methodology of science:
- A model is a tool oriented primarily toward investigating the behavior and properties of a specific object, with the aim of controlling it or predicting its properties.
- A theory is a more abstract instrument than a model, whose primary purpose is to explain the behavior or properties not of a single specific object but of an entire class of objects. One could say that a theory contains a finite or even infinite collection of specific models.
When constructing a specific model, the laws and equations of the corresponding theory are used. A model answers the questions "How?" and "Why?" for a particular object, while a theory answers them for an entire family of objects that share similar properties. It should be noted, however, that when developing models of complex processes and phenomena, it is often necessary to draw on concepts and relationships from several theories belonging to different branches, disciplines, and even fields of knowledge.
Models can be constructed in the imagination — mentally, by means of thought — and such models are called abstract. Alternatively, models can be created from real objects and processes, in which case they are called real, material, or sometimes physical models. In a sense, an intermediate position is occupied by real models with abstract content — symbolic (sign-based) models. The concept of a model does not pertain to the object alone; in certain respects it encompasses: the subject organizing the modeling effort and the task for which the modeling is undertaken (both through the goal); the original object being modeled; the means from which the model is created; and the environment in which the model is to function.
"By a model we shall mean simplified — or, if you will, packaged — knowledge that carries quite specific, limited information about a subject (phenomenon), reflecting certain of its properties. A model can be regarded as a special form of encoding information. Unlike ordinary encoding, in which all the source information is known and we merely translate it into another language, a model — whatever language it may use — also encodes information that people did not yet know. One could say that a model contains potential knowledge which a person, by investigating the model, can acquire, render explicit, and put to practical use in everyday life" (N. N. Moiseev).