Zhu Bajie is a famous monster in Chinese mythology, half man and half pig. Can he be a fashion model too? See the declarative sentence, “she is a woman” and “she is a model”, in which “is a” has different meanings: the former means that she is essentially a woman; the latter means that she is played a role which is called model, exactly, just when she is working for, or some one taking her as. Talk about this topic since just see Marco Brambilla’s pretty essay Reason and meaning of (top) models. His main point is to explain that “you cannot avoid modeling”, I do agree that; some similar opinion is expressed in such Models Make Us Running on the World.
Marco used an beautiful top fashion model as an example, this is also used to be one of a few typical examples I repeatedly thought about and like to use to explain the idea of Model as Use, defined model as below:
we call an entity model while it plays the role in the situation where the entity has and provides a set of properties directly or indirectly as the substitute for a thing else.
I prefer give some different saying than Marco, for a fashion model, first, one is a model just when she/he is severed as a model, and the “certain properties” may be the devil figure and may also be fat appropriately :-), it is depended on the ideal object (the target been modeled) imaged by the users with their purposes; anyone can in fact potentially be served as a model, not because she/he is handsome but can provider the properties. This is even said by Marx W. Wartofsky, “anything can be a model of anything else!”
One maybe say that it is not necessary to such depth and detailed definition of model for most study and practice of software applications; I generally agree, too. But it may be the point for understanding some deep issues and to obtain more benefit from models and modeling, such some Model Muddle on Computing, as well as the difference between modeling and programming and there is an interesting discussion at Why programming is much harder than modeling? by Jean Bizivin, or some subtle topics in metamodeling.