Philosophy
The Doctrine of Double Effect
Quick fact
The doctrine was first formally articulated by Thomas Aquinas in the 13th century to address situations like self-defense where killing an attacker might be permissible if the death is unintended.
Why this is interesting
You deliberately swerve your car to avoid a child, hitting a tree and injuring yourself. But what if that same swerve also hits a pedestrian? Did you intend to harm the pedestrian, or was it an unavoidable side effect? The Doctrine of Double Effect tries to answer whether your action is morally justified.