One of the unquestioned assumptions behind object-oriented programming is that objects are instances of a class, and thus implicitly stay that way. This is akin to the philosophical concept of nature, as in an invariant quality of something, that cannot be changed:

But is there any one thus intended by nature to be a slave, and for whom such a condition is expedient and right, or rather is not all slavery a violation of nature?

There is no difficulty in answering this question, on grounds both of reason and of fact. For that some should rule and others be ruled is a thing not only necessary, but expedient; from the hour of their birth, some are marked out for subjection, others for rule.

…

Again, the male is by nature superior, and the female inferior; and the one rules, and the other is ruled; this principle, of necessity, extends to all mankind.

…

It is clear, then, that some men are by nature free, and others slaves, and that for these latter slavery is both expedient and right.

Aristotle, Politics I, 5 (emphasis mine)

Needless to say, this concept is reactionary. One may well object that given slavery’s omnipresence in antiquity, even a great philosopher such as Aristotle could not be entirely free of the prejudices of his time. This conveniently ignores the fact Aristotle was a pupil of Plato, himself a disgruntled aristocrat who collaborated with Spartans when they overthrew Athenian democracy after the Peloponnesian war, and is arguably one of the theoretical founders of the totalitarian state. I would say it is rather the presumed greatness of Aristotle that should be reexamined, but I digress. For more on this subject, read Karl Popper’s The Open Society and its Enemies – Volume 1, The Spell of Plato.

Thus, OOP carries within it the conservatism of Plato and Aristotle, people who resented how the young Athenian democracy had usurped the aristocracy’s natural (in their eyes) right to rule over others. This is not just an academic consideration. Computer programmers influence society, specially those who work for governmental information systems, and if you consider the Sapir-Whorf hypothesis, the language they use affects the way they think.

This is why I like Python’s ability to morph an object from one class to another:

Python 2.2.1 (#1, Apr 18 2002, 13:06:27)
[GCC 2.95.3 20010315 (release)] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> class Slave:
...     def whip(self):
...             return 'Yes, master'
...
>>> class Freeman:
...     def whip(self):
...             return 'Die, fascist scum!'
...
>>> man = Slave()
>>> man.whip()
'Yes, master'
>>> man.__class__ = Freeman
>>> man.whip()
'Die, fascist scum!'