Hindsight is 20/20. Most people today view slavery, child labor, and the oppression of women as wrong, but this change only came about because thoughtful people called for justice and fought oppression, even at great personal risk.
Will future generations look back at ours with the same shame and horror we feel when we read about ships crammed with slaves or about the forced winter march of American Indians away from their homelands? An objective look reveals that our generation still operates in the same way. The only difference is that yesterday's victims - used and abused because they were "different" and powerless - are now of other species.
Cruel actions that would cause a public outcry today - such as the use of children who had mental disabilities at New York's Willowbrook State Hospital in 1960s hepatitis experiments - are no longer tolerated because we accept that harming other humans simply because they are defenseless is reprehensible. Traveling circuses rarely display physically deformed men and women as "sideshow freaks" to be gawked at and ridiculed anymore because we now know that individuals deserve respect and consideration no matter how they measure up to the norm. Yet intelligent, social animals are still used in experiments, circus acts, and other abominations.