[carstimon]

I think this is in response to

> Why should my Dog be able to check out the internal StomachContents of another Dog

This seems to be interpreting the purpose of visibility as controlling the access that actual things represented by objects have. (There could be a non oop-as-real-world-things example here; `UserProfile.equals(UserProfile other)` might access secrets of `UserProfile` that the different actual users are not supposed to see between each other.)

The reason Dog can check the internal details of another Dog is, there's a single file that controls the usage of the fields. If you decide you want to change the semantics of the stomachContents field, you can check all the usages in that file. That's the simple practical reason. The StomachContents thing seems like a confusing analogy, like most that compare OOP to Real World Categorization.