In another topic ("Which U.S. Presidents Would Have Shrugged") the discussion turned to slavery.

Slavery was an invention. Previously, in warfare, the losers were all killed. Agriculture made it possible to keep them alive as captive workers. That, however, is just one story from one place and time - Sumeria. Slavery existed in other cultures, as well, but not in all agricultural societies. Legal slavery was rare in China, for instance, and certainly was never on the scale of the Middle East - or ante-bellum South.

Aristotle said that it was wrong for Greeks to enslave other Greeks. Barbarians were to be enslaved, but not Greeks, though, indeed, Greeks did enslave each other. Aristotle offered a moral imperative.

Similarly, the proto-libertarian Aristippus of Cyrene argued for his own individual freedom. He was questioned quite directly about his slaves. He allowed the contradiction, but, he said, that's life: I have my freedom; they do not have theirs. Again, circa 300 BCE, anyone who thought about it understood the problem.

It was argued in that discussion that slavery was necessary to harness labor (literally) needed for farms. However, any historian of technology will tell you that the institution of slavery in Hellenistic and Roman society was a barrier to the adoption of machines, such as Heron's steam engine.

Moreover, with the decline of the Roman empire in the West, slavery was abandoned, and then abolished. Except for punishment, the Germans generally had no need for slaves, yet they farmed the same lands as the Romans had. They did, of course, raid other people and sell them in the Eastern Roman Empire where lawful slavery continued. In Slavic languages, "slav" just means "people" but the word is the root for our word "slave" because they were the ones raided and sold.

When Hungary christianized under King (Saint) Stephen, it was the end, not the beginning of a process. Christian missionaries from Constantinople had entered into the land in the previous two generations. However, King Stephen was influenced by his mother's German monks. He aligned with Rome. That met with resistance from the nobles who held slaves. They had to give them their freedom, make them serfs, because Rome did not endorse slavery.

Thus, historically, it is clear that productive agriculture was certainly possible without slavery. Nonethless, slavery continued and was extended.

Over the centuries, the morality of slavery was debated. (Thomas Aquinas argued for it.) The fact that it was debated indicates that slavery was considered questionable.

It is an error to project ourselves on the past. Even 100 years ago, some of the best physicists denied the existence of atoms. ("Have you ever seen one?") You cannot expect people to know what they did not know.

At what point, then, does one person hold another morally responsible for their actions? "I didn't know any better" is a child's excuse. We expect adults to have the same insight and awareness that we do,now, in the past, and in the future.

Mining the past for exceptions is interesting. It may not be fruitful out of context. Aristarchus of Samos put the sun at the center of the planetary system, with the Earth going around it. If so, said Archimedes, then the stars will be in different apparent positions between summer and winter. Archimedes failed to measure any such parallax. So, he placed the Earth at the center. And so, too, with slavery, perhaps, while many argued against it, the social facts lined up in favor of it.

But if that is true about slavery, what can we say about the Progressive Era in which eugenics, the income tax, centralized banking, and the cartelization of industries, all were invented?

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