How does own affect binding relationships?
I am studying binding theory as it applies to English. I have learned that own can influence the binding relations. For example:
(1) John is his boss.
The bolded words cannot be coreferential in this sentence, but when one adds own, they necessarily become coreferential:
(2) John is his own boss.
My question now concerns the fact that the pattern is different when a content verb appears instead of copular be, e.g.
(3) John likes his boss.
The word own does not appear in this sentence, yet the bolded words can easily be coreferential. Why? How does binding theory account for this difference? It somehow relies on whether copular be or a content verb appears. But why would that be the case?