We have built in prejudices about the value of other things, prejudices that are largely responsible for our evolving into what we are. We value animals above plants, humans above other animals, our own race above other humans, our tribe above others of our race and our family above others of our tribe. In our more primitive past, it had been beneficial to exploit these "others". Upon becoming "civilized" we no longer accept exploitation as a de facto acceptable behavior. This does not change our exploitative behaviour though. The first step is to engage in rationalization. Rather than giving up slavery, we come up with "good" reasons for it. The step from exploitation to rationalized exploitation is generally accompanied by much self-congatulatory admiration for how civilized we have become. The next step, to the cessation of exploitation is usually a real ***** of a struggle.