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very basic questions

In Uncategorized on March 4, 2010 by wenwenfan

Hi all,

My first exposure to philosophy of science is this class, so I really get confused at some very basic distinctions or terms. I hope you can help me out.

1. model vs. theory

Dan told me that a theory has scientific language and can be tested  while a model has not scientific language. If a model cannot be said to be true or false, just whether it can be applied to explain/predict a certain phenomenon, then how can we judge whether a model is good or bad relative to the target phenomenon?

Weisberg talks about several kinds of representational ideals. It seems that if a model can achieve the desired ideal, then it is good. Then, does it mean that whether a model is good is relative to the time as well? For example, when technology advances, we need to de-idealize Galilean idealization. But is it true with the other idealization, that what is a good minimal idealization now is not a good one in the future? So, there is no best model period?

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6 Responses to “very basic questions”

  1. I think that a model is good provided that relevant features of the model map to relevant features of the phenomenon the model represents. By relevant, I think that what you’re trying to describe is important (e.g. if I want to model the aerodynamics of a car, the color, material, weight, etc. of the model is unimportant). As a result, Weisberg is right to relate a model’s “goodness” to how well it achieves its representational idea.

    Regarding Galilean idealization, you’re right to say that time is relevant, but this is not necessarily so with minimalist idealization. The best minimalist model is the one that will capture the primary causal factors, so if you capture those, you have the “best” minimalist model. If, at time T1, some important causal factor X has not been discovered, but at time T2, it has, then the model at time T2 should be accepted over the model at T1. But, unlike Galilean models, which assume relevant advancements, there is no assumption that X will be discovered. So, you could say that Galilean models are the “best for now”, while minimalist models are “tentatively best” models.

  2. The basic definition of ‘theory’ that I learned in my science classes was, ‘a scientific hypothesis that has stood the test of time.’ A theory does not necessarily have to be a model, but it can be. For example, evolution as the origin of species is considered a theory, but there is no mathematical model that encompasses the entire theory of evolution. Another example would be the theory that space is relative rather than absolute with the Earth in the center.

    Similarly, models do not necessarily represent scientific theories, even in idealized forms. The action figure of Stalinist Superman on my bookshelf is a model of the comic book character of Superman (if he landed in Ukraine rather than Kansas), and has little to do with anything remotely scientific.

    In addition, models can have utility, but not represent any viable scientific theory. Ptolemy’s geocentric model was still used for predictions of phenomena after Copernicus became the scientific theory (his model was more accurate in predictions than Copernicus). Thus it is always potential that a model has nothing to do with science or how we think the phenomena really works. There are models of the universe where the Earth is an inverted sphere and the sun is the center of the universe, but the ‘laws’ governing it are so convoluted so that the theory might conform to phenomena that it is largely discounted.

    So, theories are not models. Theories can often be represented as models. Not all models represent theories. Models can often have no relation to currently valid science.

  3. Dammit!
    “There are models of the universe where the Earth is an inverted sphere and the sun is the center of the universe, but the ‘laws’ governing it are so convoluted so that the theory might conform to phenomena that it is largely discounted.”

    ‘Theory’ here is not being used in the technical sense, and I should have used ‘hypothesis’ or maybe ‘silly idea’.

  4. Jake and Todd,

    Thank you for the comments! The question how to evluate a model and what’s the relation between theory and model seem more difficult to answer since I read the Stanford Encyclopedia’s entry Randy pointed to. According to that entry, even Weisberg’s categorization of three kinds of idealization may not be the correct story (at least not the whole story) about models. (Jake, there is even a sort of model called “analogical model”!). Todd, you are right, there is no straightforward relation between theory and model.

  5. It might also help to read this Morgan and Morrison article that seems to be cited everywhere (“Models as mediating instruments,” from Morgan M, Morrison M (eds) Models as mediators (1999), pp. 10-37.). It will at least give an argument that one could evaluate regarding whether or not models are autonomous from theories.

  6. Thank you, Jenny. I’ll check it out.

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