Models are not real.

My department has had two speakers this semester who said some variant of "models are not real." From my physics training, that statement is obvious. There are tons of jokes about physicists stating their ridiculous assumptions before they start to solve a problem. But the reason the assumptions seem outlandish is that they explicitly state the difference between their model and reality. As the complexity of the system grows beyond a hydrogen atom, even articulating those differences quickly becomes impossible. And that is ok. The point of a model is not to be real, it is to be useful.

So how is all this a problem? In engineering we really cannot state all the assumptions we make in our model. Instead we focus on stating assumptions we make that may be different than those other people in our field make. But if an entire field has been making the same invalid assumption, there is no obvious opportunity to identify it.

This is where empirical work and diversity can help. If we find that some observed phenomenon is not captured by our model, we can change the model. If someone who is new to the field asks questions about something we didn't even realize we were assuming, we can change the model. As long as we try to focus on what we want our model to do, we can try to include the important features of reality to get meaningful results.