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Hmm, medical scientists experiment on rats and then make medical predictions about humans based on analogy from rats to humans. At least, I classify this as an

Hmm, medical scientists experiment on rats and then make medical predictions about humans based on analogy from rats to humans. At least, I classify this as an analogy, and wouldn't forbid analogies from having predictive power. Re: "reveal aspects of interactions in the system I was not aware of" I think this is an interesting point. I definitely am willing to give persuasive force to e.g. theoretical microeconomics, which like system dynamics operates by analogy from a mathematical construct to humans. I think in principle I could believe a non-obvious prediction made by a system dynamics model where I felt that the mathematical constructs in the model were a good analogy to humans -- but the prediction would have to be robust, i.e. it shouldn't vanish if you change the parameters of the model or tweak the assumptions of the model. Theoretical economists tackle this by making their results super general using abstract math and characterizing the solutions to systems of inequalities in the most general form that they can.

lukeasrodgers 4y ago
I wouldn't classify rats<->humans as an analogy in this context. Generalizing (too broadly, probably) premodern medical "science" was explicitly analogical in many ways, e.g. "we will use this herb that looks like an eye to cure your eye trouble" but that is obviously completely different than the experimental/genetic basis on which we use rats as a medical model for humans. OTOH, since arguing over semantics is mostly a waste of time, if you want to call it an analogy, then fine, but I would say you need to drop your "mere" from the original article, which is doing a lot of the work in that argument, since clearly analogies in your view are quite powerful, have predictive power, etc. I hope this doesn't come across as overly pedantic, I just find thinking about these things very interesting. Not sure I understand your point about such models needing to be robust in the face of different parameters. I was working on a model the other day which I discovered had very different behaviour based on the initial parameters in a way that will have direct impact on the software I'm writing/business process I'm developing, making it safer and more predictable. Maybe that outcome should have been obvious, but it wasn't to me (or at least, I suspected something like it, but wasn't able to reason through to the conclusion without the aid of a model). In this case, I consider the fact that different predictions were made based on altered initial parameters to be a strength, not a weakness. But going back to your point "you should only give it force if the stories it tells are plausible in light of your experience and knowledge," I agree and if the model were outputting very surprising and counter-intuitive predictions, I would start by assuming the model was wrong, not my intuitions.

lukeasrodgers 4y ago

I wouldn't classify rats<->humans as an analogy in this context. Generalizing (too broadly, probably) premodern medical "science" was explicitly analogical in many ways, e.g. "we will use this herb that looks like an eye to cure your eye trouble" but that is obviously completely different than the experimental/genetic basis on which we use rats as a medical model for humans. OTOH, since arguing over semantics is mostly a waste of time, if you want to call it an analogy, then fine, but I would say you need to drop your "mere" from the original article, which is doing a lot of the work in that argument, since clearly analogies in your view are quite powerful, have predictive power, etc. I hope this doesn't come across as overly pedantic, I just find thinking about these things very interesting. Not sure I understand your point about such models needing to be robust in the face of different parameters. I was working on a model the other day which I discovered had very different behaviour based on the initial parameters in a way that will have direct impact on the software I'm writing/business process I'm developing, making it safer and more predictable. Maybe that outcome should have been obvious, but it wasn't to me (or at least, I suspected something like it, but wasn't able to reason through to the conclusion without the aid of a model). In this case, I consider the fact that different predictions were made based on altered initial parameters to be a strength, not a weakness. But going back to your point "you should only give it force if the stories it tells are plausible in light of your experience and knowledge," I agree and if the model were outputting very surprising and counter-intuitive predictions, I would start by assuming the model was wrong, not my intuitions.