> versus the 60s when Alan Kay coined the term It was in the 70s, and his description that I quoted is from the 2000s. > Alan Kay considers that inheritance a

> versus the 60s when Alan Kay coined the term It was in the 70s, and his description that I quoted is from the 2000s. > Alan Kay considers that inheritance and polymorphism are not essential, fine. Polymorphism is a logical outcome of his requirements. So in a purely logical sense it is essential, although I imagine that saying that might be a little bit like saying that CO2 is essential for a campfire (as in that you can't get a campfire without emitting CO2, even though that is strictly a matter of consequences). > He does consider encapsulation essential, though. Yes, because biological cells are encapsulated. > there are well-known OO principles. Claiming otherwise is either disingenuous or ignorant. There surely are some "well-known principles" but whether the "known" in that phrase has the same meaning as in "knowledge" (justified true belief at a first approximation) seems debatable.