[nabla9]

It was proper to call you ancestors slaves and their owners master.

In the same way it's proper to use same concept as a metaphor to describe other relationships where one thing is owned by other. There is nothing wrong or offensive in the concept of slavery. Even when the context is enslaving humans.

Slavery is immoral, but the concept of slavery is not.

[dragonwriter]

> In the same way it's proper to use same concept as a metaphor

Use as a metaphor depends on similar perception of the resonant features of the literal use since it relies on those carrying over to the nonliteral use; it is eminently clear that within our society there is not a common share perception of those salient features, so it is not a particularly good metaphor outside of narrow homogenous subcultures, and what it is a good metaphor for within each of those subcultures will be wildly different.

Metaphor is inherently highly culture-dependent.

[nabla9]

Slavery as a concept is very clear across cultures in a way that makes good metaphor.

Slave is actor without autonomy. Master is controlling and owning the slave.

[smsx]

By this logic, you think that something has to actually occur first before one can be morally opposed to it? I would have to first witness a genocide before I can have moral opposition to it?

Of course concepts can have moral weight. To suggest otherwise is foolish.

[nabla9]

Using concept has no moral weight.

Using word slave in a sentence is not a connected to morality of slavery.