Something we can all relate to is the fact that we always choose what we view is the best choice in a given situation. But sometimes, that decision is flat out stupid. I don't care how smart you are - we all do this.
One of the most painful experiences you can encounter in life is seeing a loved one be hurt. Even worse is when it's their decision - when it's intentional and rationalized, but still damaging. No matter how hard you try to help, nothing will convince them they're making a mistake because to them it makes sense.
A person who chooses to jump off a bridge has a reason for doing so. Otherwise, they wouldn't do it. Those of us on the outside of the situation can clearly see the issues with that idea. We know that choice will negatively affect others and we understand it's a terrible occurrence. But someone in that situation has a perfectly logical reason to back up their judgment.
That's a sensitive topic, but I'm trying to make a point.
Everyone knows that emotions can be deceiving, but we forget that logic can do the same. And when it's logic, it's just as dangerous (if not more so). We all do this, and to varying degrees, but we shouldn't forget that we always rationalize our stupid choices. In that case, I suppose it isn't logic alone that determines right from wrong.