because it was practiced virtually everywhere in the ancient world.

因为奴隶制在古代事实上广为实践
You will notice that he frames his analysis in the form of a debate.

你会注意到他的分析是以辩论的框架展开
He says at the outset of his argument, "There are some," he says,

他在论点的开头说"有些人"
indicating this is an opinion held by many people.

表明这是很多人持有的想法
"There are some who believe that slavery is natural,

"有些人认为奴隶制是自然的产物
because ruling and being ruled is a pervasive distinction

因为支配和被支配有着普遍的区别
that one sees all societies practice."

在社会实践中显而易见"
But he says, "Others believe that

但他又说"另一些人认为
the distinction between master and slave is not natural,

主人和奴隶的区别不是自然的
but is based on force or coercion."

而是基于武力和压迫"
Even in Aristotle's time,

在亚里士多德的时代
it appears slavery was a controversial institution

奴隶制也是受争议的制度