Barring believes which attribute consciousness and conscience to the universe itself, the only sense of good and bad are always relative to human perspective.

Human perspective however, is influenced by many things including, culture, religious beliefs, social and civil agreements and personal experiences. Rarely are we able to find agreement within a wide array of global societies on exactly what should be considered good and bad by all humans.

If there were such a thing as inherent human values which dictate a sense of what is good and bad, then it would be easy to have a world-wide consensus on exactly what ‘for the common good’ means, and what behaviors are valued most in order to achieve ‘the common good’.

Humans also have this phenomenal ability to adapt their notions of what is good and bad by making justifications for behavior when it no longer aligns with stated values. What was once bad becomes not quite as bad if… justification.

The habit of making such justifications has created a sliding spectrum effect which allows humans to ignore their own conscience and avoid guilt while still maintaining a value system by which to cast judgments on others.

The point is that we neglect to define words like, good, bad, evil and love in context to the interconnectivity between humans and humans, humans and other life forms, and humans and the environment.

Humans require other humans for species continuance, humans require a diversity of other, than human, life forms, and both humans and the other life forms require a rather limited balance within the echo-system which cannot be maintained without humans and other life forms.

Yet in determining the values that will guide human behavior, humans seem to have a rather egotistical view of ‘the common good’.

Therefore, humans tend to make good and bad strictly about what is good for humans and specifically, what is considered good in the context of a rather limited cultureal, social, and civil view.

If all human beings are substancially or fundamentally the same, then there should be a universal difinition of good and bad at a fundamental level.

what is not good for you is bad!

Slavery, at one time it was perfectly acceptable to own slaves both morally and legally.In 1912 if you got a woman pregnant is was perfectly acceptable to lie about it and the mother's family to raise the child as a "Brother or sister" There is no good and bad. The lines are all in your head.

How many slave owners would have enjoyed being slaves? Did the slaves agree that slavery was "good"? Were white people enslaved as well as black? None, no and no, right? So white people knew that slavery was morally indefensible, but they made an exception for black people. Exceptions don't prove that a practice is "moral".

EDIT: And if slavery was morally good back then, wouldn't it still be morally good? If not, what changed? And who is to say that slavery wouldn't become morally good again in the future?