Ancient philosophers

Philosophers justifying slavery

Throughout history there have been people who attempted to justify slavery. Many of them did so purely out of self-interest, in order to continue a barbaric trade, but some historical philosophers sought to justify slavery from the best intentions.

Aristotle

The great Greek philosopher, Aristotle, was one of the first. He thought that slavery was a natural thing and that human beings came in two types - slaves and non-slaves.

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... Aristotle, Politics

Some people, he said, were born natural slaves and ought to be slaves under any circumstances. Other people were born to rule these slaves, could use these slaves as they pleased and could treat them as property.

Natural slaves were slaves because their souls weren't complete - they lacked certain qualities, such as the ability to think properly, and so they needed to have masters to tell them what to do.

It's clear that Aristotle thinks that slavery was good for those who were born natural slaves, as without masters they wouldn't have known how to run their lives.

In fact Aristotle seems to have thought that slaves were 'living tools' rather like domestic animals, fit only for physical labour.

And indeed the use made of slaves and of tame animals is not very different; for both with their bodies minister to the needs of life. Aristotle, Politics

Slaves were not totally incapable of thought, but they only needed minimal amount of rational ability; just enough to understand and carry out their duties.

Similarly, slaves were not devoid of 'virtue', but once again, they only needed just enough to carry out their duties. But that 'virtue' was enough for them to be treated as human beings.

Aristotle doesn't provide any sensible practical method of recognising natural slaves, and without that it's inevitable that some people will be made slaves who should not be.

Aristotle also had a category of 'legal slaves'; they weren't natural slaves but through bad luck - perhaps being taken prisoner in war - they just happened to be slaves at a particular time.

Aristotle argued that if the world was just, the legal slaves would be freed, and if any natural slaves were by chance free, they should be made slaves.

Plato

The Greek philosopher Plato thought similarly that it was right for the 'better' to rule over the 'inferior'.

...nature herself intimates that it is just for the better to have more than the worse, the more powerful than the weaker; and in many ways she shows, among men as well as among animals, and indeed among whole cities and races, that justice consists in the superior ruling over and having more than the inferior. Plato, Gorgias

Homer

Homer seems to have thought that even if a person wasn’t inferior before they became a slave, enslaving them changed them in such a way as to make them a natural slave: