Read on Twitter
People, including me, like to quote Feynman saying "what I cannot create, I do not understand." (Da Vinci said something similar). However, this dictum is too simple. It misses something important.
The reductio of this logic is that ultimate understanding is achieved when one can create a perfect copy of an object. But at that level of detail, the object is utterly unique, since it doesn't share atoms with any other object.
This means that a "perfect" model (in the sense of exact copying) cannot be generalized to any other object. Such understanding is inductively inert.
For example, when we talk about "understanding the brain", we don't mean any particular brain but the set of all brains. A perfect copy of any particular brain would be useless for this purpose.
When we say we understand something, we don't mean that we can create a perfect model, but that we can create a deliberately imperfect model. This abstraction is what allows our models to generalize. So we should really say, "what I cannot generalize, I do not understand."
