Final answer:
Physical invasion in defense, private or public necessity, is used to protect personal or property rights when they are threatened. Defensive force is used for self-defense, while retaliatory force is used as retribution. The government also has the power to protect individuals through force.
Step-by-step explanation:
In the context of defense, private or public necessity, the intent of physical invasion is to protect one's personal or property rights when they are threatened. Defensive force is used to defend oneself and ensure safety, while retaliatory force is used as a form of retribution against those who initiated force. The government also has the power to protect individuals through defensive force. This type of force is considered valid and necessary for self-defense and justice.