If I ever go on an online dating site, you know what my pet peeve will be? People who say of thought experiments "But that's not true in the real world!"

The capacity for abstract thought is perhaps the most precious gift of our foresighted ancestors who elected evolution over another 10 million years poking anthills with sticks. Why are these people so determined to fling the fruits of this noble legacy away? I tell you, whenever someone tells you "but that's not how it works", know ye by these presents that lurking somewhere back in their family tree was a hairy primate whining "I'm tired of walking upright! Why can't we give up this fire nonsense and head back into the forest?" And that primate was hated by all the other, smarter primates in the tribe.

Models and thought experiments are designed to illuminate principles, not mirror the real world. We already have something that looks and works exactly like the actual world: that is, the world. However, if you want to learn much about that world beyond "Water is wet" and "Fire burns", you need to simplify in order to see deep truths more clearly.

Sentences that start, "In the real world . . . " or "Tha'ts just a model . . . " are indeed damning indictments, but not of the simplification.