Gilber Ryle captures, I think, the essence of our discussion in the introduction to The Concept of Mind: "The philosophical arguments which constitute this book are intended not to increase what we know about minds, but to rectify the logical geography of the knowledge we already possess."

Pretty much, we are trying to find the home for models, or if they even have a home at all. Once we corner one, then perhaps we can understand how a model makes us, well, understand at all. That plastic solar system model doesn't seem to be doing much sitting on the table. It hasn't been clear to me yet how its supposed mental counterpart could be more effective.

Modern philosophy sees language not as words, but as "forms of life", that is, us going about our business in this or that fashion. Words are like tools that we use amongst ourselves to accomplish, to query, to console, to love, to humor, to chide, and so on. In a word: experience.

Let me make it clear that I am not disagreeing with you in the sense we posters often disagree with each other on these forums. I am not accusing you of anything wrong. Going back to Ryle, at best I am suggesting an alternate logical geography, or organizing things a little differently.

First, notice that you cannot make a direct argument for the model. You are trying to show there is a model here, but all that is on hand here is a clerk bumbling a financial transaction. As an explanatory device, the model here is no better than a creationist who follows everything said by a biologist with, "And God created it to work like that!"

And second, and most importantly, you tried to draw my attention to some model changing, but what actually changes here in this example is the clerk handing back the correct change. Perhaps he also tells you (or thinks privately), "Oh, I see, 20 minus 17 is 3. I won't make that mistake again." And perhaps he always gets that transaction right in the future. There is a wider pattern of action and interaction that has changed. You observe that pattern, which prompts you to ascribe a faulty inner model that the clerk revises as an explanation. That technique works in practice whether there is a model or not. In the latter case, talk of a model avoids having to consciously scrutinize and describe the details of the activity. That's the nature, and advantage, of folk psychology. (A consequence of "model" being your ascription to the clerk is that you have a hard time finding the model when a spoilsport like me comes along and pesters you directly identify the model!)

It's telling that what prompts Len, Ken, and yourself to speak of models are acts of human failure. It shows that if the term "model" refers to anything, it is to those acts and their consequences.

I might say here that theory is a species of human procedure. I have likened a scientific theory to a cookie recipe in other threads. "Do something using simpler portions of the data" describes an economy of procedure, that is, getting the same bang for fewer of the bucks. Newton put the cosmos in reach of the talents of high school students.

Science shows us how to act economically. It discovers and teaches techniques that can be applied to many particulars, perhaps an antibiotic that can treat several types of infection. In that sense, science is of the particular, just groups of them.

That's the spirit. Keep an eye out for metaphor in philosophic arguments. A good deal of modern philosophy tackles philosophic problems by dissolving them through working to get clear about the language and its role.

We are just trying to get clear here on what is actually getting built and how having that built thing helps us in any way. If a plastic model of the solar system is not knowledgable, how does a mental version of it make us so?

Yes, maps are clear-cut instances of models. I am asking for the equivalent in the case of a scientific theory or of the clerk who handed back the wrong change.

While we are on the subject, consider a map for a moment. A map is just ink markings on paper. Ink markings and paper in and of themselves cannot be right or wrong, faithful or faulty, correct? There is a context of environment and of activity that surrounds the map, that makes the map a map of something. The fault exist only in the wider context that includes the map, human map reading and navigating procedure, and Columbus' ships failing to reaching Asia. If you try to narrow down to a single something, a model, then the property of fault vanishes. I suppose some have gone off course because they did not use the projection system of their map appropriately. In that case, either the map or the navigation process could be revised to resolve the fault. Fault is a property of the larger dynamic system.

Newton worked for hours timing pendulums and pestering astronomers for measurements. He kept changing his procedures, his recipes until he could apply them to both pendulums and planets. He placed himself in a dynamic feedback loop with the world in a way nobody ever achieved before. He wasn't building a replica of the world, a model if it, as much as he was finding a way to best take advantage of its affordances. We must act to live well. How to act is the problem scientists solve for us.