> To know anything (an X) completely you need perfect knowledge.
Agreed.
> Hence people come up with a set of simplified ways of reasoning about X. They call this a model of X.
A "set of simplified ways of reasoning about X" in order to create a "model of X" does not imply complete understanding. Quite the contrary actually.
To wit, science often models current understanding of a phenomenon. When new evidence (understanding) is discovered, the model is updated to account for it. Sometimes this invalidates the original model, often the model is refined. Either way, progress is made with the tacit agreement that the model may change in the future.
> If a model checks out with the real outcomes we proudly exclaim that we understand X.
Again, this does not support the assertion of "That's been solved long ago." If anything, it affirms there is justification for disagreeing with the original premise to which I responded:
> We just can’t accept that we might solve ourselves.
Agreed.
> Hence people come up with a set of simplified ways of reasoning about X. They call this a model of X.
A "set of simplified ways of reasoning about X" in order to create a "model of X" does not imply complete understanding. Quite the contrary actually.
To wit, science often models current understanding of a phenomenon. When new evidence (understanding) is discovered, the model is updated to account for it. Sometimes this invalidates the original model, often the model is refined. Either way, progress is made with the tacit agreement that the model may change in the future.
> If a model checks out with the real outcomes we proudly exclaim that we understand X.
Again, this does not support the assertion of "That's been solved long ago." If anything, it affirms there is justification for disagreeing with the original premise to which I responded:
> We just can’t accept that we might solve ourselves.