Who made this theory?
St Thomas Aquinas
What is this theory?
A war should only be fought for a cause that is morally justified
Jus ad bellum
Last resort - War must be the last resort
Legitimate authority - War must be lawfully declared by a government with the authority to declare war
Just cause - There must be a just cause and proper intention for the war
Reasonable success - There must be a reasonable chance of success
Jus in bellum
Good outweighs evil - The good gained by winning the war must be greater than the evil caused by fighting it
Proportionality - there must be proportionality, only ‘appropriate force’ should be used.
Innocent shouldn’t be killed
Peace restored at the end