The answer to this question is supposed to be in "The Early History of Smalkalk", though I haven't re-read it.
Anyway, I just asked on the Fonc mailing list, and got an incredibly detailed answer from Alan Kay himself. To sum it up, someone asked him what he was doing, and he didn't quite have a name for that yet. Heck, he was at the stage of narrowing it down mathematically. So he just answered "object oriented programming", because it fitted with the vocabulary of the time, and went back to work.
He did later regretted this label.
Now, it's not even sure a better terminology would have helped much. Alan Kay reckons that "it might have helped to have better terminology", but it would probably have been hijacked too:
> The success of the ideas made what we were doing popular, and people wanted to be a part of it. This led to using the term "object oriented" as a designer jeans label for pretty much anything (there was even an "object-oriented" COBOL!). This appropriation of labels without content is a typical pop culture "fantasy football" syndrome.
Anyway, I just asked on the Fonc mailing list, and got an incredibly detailed answer from Alan Kay himself. To sum it up, someone asked him what he was doing, and he didn't quite have a name for that yet. Heck, he was at the stage of narrowing it down mathematically. So he just answered "object oriented programming", because it fitted with the vocabulary of the time, and went back to work.
He did later regretted this label.
Now, it's not even sure a better terminology would have helped much. Alan Kay reckons that "it might have helped to have better terminology", but it would probably have been hijacked too:
> The success of the ideas made what we were doing popular, and people wanted to be a part of it. This led to using the term "object oriented" as a designer jeans label for pretty much anything (there was even an "object-oriented" COBOL!). This appropriation of labels without content is a typical pop culture "fantasy football" syndrome.