If you knew for a fact that an action of yours would have a direct, immediate and profoundly negative effect on your next door neighbor, a beloved friend or family member, would you do everything you could to change your behavior?
What if it were someone who lived down the street but for whom you had no strong feelings?
What if the connection between your action and the harm was less immediate, less direct but still connected?
What if the action harmed, not a neighbor but someone you would never meet, a person in another place, another town or another country?
What if it wouldn't hurt someone alive now but would harm people in the future, possibly your children or your children's children?
What if there was no way to measure the impact of your actions to gauge the harm?
What if everybody did it and you were just one of many?