Assuming good intentions

One thing that history should have taught us is that many people do not act in good faith. Any number of incidents that are well documented, show that many agreements have been signed where one of the parties felt absolutely no moral obligation to honor it. Consider Hitler at Munich in 1938, he promised to behave in a certain manner in the future in order to get what he wanted then. The promise meant nothing to him. More recently you can consider Bernie Madoff, not to compare him to Hitler in scope of destruction, who lied to people who trusted him because he was "one of them".

Perhaps a better example is to consider how many people violate their wedding vows. They rationalize their behavior in any number of ways, if you believe a vow can simply be violated because you think it can. I would argue that if the old adage about history repeating itself has any meaning it is in the fact that agreements will be broken and betrayal is a fundamental human characteristic.

It may not be a universal one. The problem of the magic ring that Plato posited is still out there for moralists to struggle with. If you possessed a ring that could make you invisible (read immune to prosecution) would there be any reason to be honest? If there is no earthly or spiritual consequence to anything you do, would you just take anything your heart desires even if it meant others would suffer?

The question has no meaning if it doesn't hurt someone else. Are we our brother's keeper? In nature the fit survive and the most fit are usually rather brutal if you think about it. When a predator kills and eats prey, it feels no remorse and has no sense that it has done something wrong. Their survival is what matters to them. Now, in nature, we do have altruism, primarily towards offspring since that trait is genetically important for a species to survive. Those offspring simply abandoned at birth generally have a reduced chance of survival.

So it is probably safe to suppose that humans share this fundamental trait with the rest of the animal kingdom. What we have developed to a greater degree than most if not all animals is the ability to deceive and betray. Now betrayal does accompany predation. Predators need to fool their prey if they want to improve their chances. Nature provides many examples, but there is no creature better skilled at betrayal than humans.