Maybe I don't get out enough but I have still not met anyone who was not dismayed by the decision taken in the House of Commons to join in the bombing of Syria. The principles of Just War theory have a presumption against the use of force, i.e. there are a rigorous set of conditions to be met before war should be launched. The principles of Just War theory state that for military action to be justifiable there must be:
1. Just Cause ... Isil/IS/Daesh is certainly an aggressor and the cause of much misery in the Middle East and also in Europe.
Conclusion: There is great cause for concern but other arguments are needed before the move into war is taken.
2. Competent Authority ... Has the Syrian government, or any other body in the country, asked for military intervention? The House of Parliament is the supreme law-making body in the United Kingdom but is there clear authorisation for military action under UN resolution 2249?
Conclusion: UN authorisation is required when no communication is received from the country to be attacked.
3. Comparative Justice ... In the West we are horrified by the atrocities committed by Isil and must avoid being drawn into committing atrocities of our own. Do the rights and values invoked justify killing?
Conclusion: Find another way to contest the moral ground.
4. Right Intention ... There is no suggestion that those who voted for military action had bad intentions, but have parliamentarians deluded themselves and become victims of their own outrage?
Conclusion: Repeat the argument that military response is not a long-term solution.
5. Last Resort ... Can we say that all peaceful alternatives have been exhausted? The Middle Eastern groups that oppose Isil have to be brought together to agree a common set of objectives for stability. It is also important that those countries buying its exported oil must stop so that Isil's funds are limited.
Conclusion: Political and economic pressure are key to defeating Isil.
6. Probability of Success ... It is difficult to achieve successful military action when there is no clear target and even worse when the target is mixed in with the civilian community. Isil does not work out of offices with large signs outside advertising their presence, so how will bombing be targeted to avoid innocent civilians?
Conclusion: Recent experience suggests that a bombing campaign has little probability of success.
7. Proportionality ... It is hard to avoid the conclusion that European lives are worth more than other lives.
Conclusion: The attacks in Paris were the spur that outraged our civilised values and drew us into a destructive bombardment that promises to be as bad as any destruction that any of the factions in Syria have inflicted on each other.
8. Discrimination ... It must be directed against unjust aggressors, not against innocent people caught up in a war not of their making.
Conclusion: This criterion is almost impossible to fulfil. Even if oil fields and the distribution system are the only targets, the environmental damage will be immense.
It is worth noting too the following declaration from Vatican II: "Any act of war aimed indiscriminately at the destruction of entire cities or of extensive areas along with their population is a crime against God and man himself. It merits unequivocal and unhesitating condemnation." Gaudium et Spes