"Terrorism", like "left-wing" and "right-wing", needs proper definition.
We can't just condemn all internal rebellions against the state, no matter what the state is like or no matter what the rebellion is like. They may be people fighting a tribal, oppressive state, but only to set up a different type of tribal state (perhaps even a worse one). They may be heroic democrats versus a tribalist state. They may be evil tribalists versus a peaceful democratic state. They may be democrats versus a totalitarian state. They may be totalitarians versus a democratic state.
We can label parties to a conflict by asking these questions:
Here are my attempts at answering these questions for various groups in the 20th and 21st centuries:
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
Al-Qaeda | NO | NO | NO | YES |
Iraq resistance | NO | NO | NO | YES |
Afghan and Pakistan Taliban | NO | NO | NO | YES |
Hezbollah | NO | NO | NO | YES |
The Ulster loyalists | NO | YES | NO | YES |
The Chechens | NO | YES (maybe) | YES (maybe) | YES |
The IRA | NO | YES | NO | NO (mostly) |
ETA | NO | YES (sort of) | NO | NO (mostly) |
1970s left-wing terrorists | NO | NO | NO | NO (mostly) |
Eco-terrorists | NO | NO | NO | NO |
Animal rights terrorists | NO | YES | NO | NO |
Anti-abortion terrorists | NO | YES | NO | NO |
The French Resistance | NO | YES | YES | NO |
Pakistan jihad against India | YES and NO | NO | NO | YES |
The Palestinians | YES and NO | YES (sort of) | NO | YES |
The Old IRA | YES and NO | YES | YES (maybe) | NO (mostly) |
Nazi Germany | YES | NO | NO | YES |
Stalin's democide of the Soviet Union | YES | NO | NO | YES |
Mao's democide of China | YES | NO | NO | YES |
Pol Pot's democide of Cambodia | YES | NO | NO | YES |
The Allies in WW2 | YES | YES | YES | YES |
Israel | YES | YES | YES | NO |
The British in Northern Ireland | YES | YES | YES | NO |
The Allies in Iraq | YES | YES | YES | NO |
The Allies in Afghanistan | YES | YES | YES | NO |
White = non-state.
Then consider the following categories.
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
Al-Qaeda | NO | NO | NO | YES |
Iraq resistance | NO | NO | NO | YES |
Afghan and Pakistan Taliban | NO | NO | NO | YES |
Hezbollah | NO | NO | NO | YES |
Pakistan jihad against India | YES and NO | NO | NO | YES |
Obviously, any such people should be ruthlessly opposed, as should state actors with worthless causes, who attack civilians:
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
Nazi Germany | YES | NO | NO | YES |
Stalin's democide of the Soviet Union | YES | NO | NO | YES |
Mao's democide of China | YES | NO | NO | YES |
Pol Pot's democide of Cambodia | YES | NO | NO | YES |
These two are by far the easiest situations to think about. Any fight against these is justified.
In fact, anyone with a worthless cause should be ruthlessly opposed, even if they fight a "clean" war:
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
1970s left-wing terrorists | NO | NO | NO | NO (mostly) |
Eco-terrorists | NO | NO | NO | NO |
This rarely happens, since most groups without a just cause tend to naturally target civilians (e.g. jihadis, fascists, communists).
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
The Ulster loyalists | NO | YES | NO | YES |
The Chechens | NO | YES (maybe) | YES (maybe) | YES |
The Palestinians | YES and NO | YES (sort of) | NO | YES |
Here, one might argue that ruthless opposition to the war crimes has to be combined with a political settlement. One can assassinate, and make peace.
Similarly problematic are state actors with a just cause who attack civilians (which was pretty much all state actors in the past):
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
The Allies in WW2 | YES | YES | YES | YES |
Do the Allied bombing crimes in WW2 cause one to oppose the Allied cause?
So we distinguish ones where violence could be legitimate:
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
The French Resistance | NO | YES | YES | NO |
The Old IRA | YES and NO | YES | YES (maybe) | NO (mostly) |
From ones where the cause, although not worthless, does not justify violence:
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
The IRA | NO | YES | NO | NO (mostly) |
ETA | NO | YES (sort of) | NO | NO (mostly) |
Animal rights terrorists | NO | YES | NO | NO |
Anti-abortion terrorists | NO | YES | NO | NO |
Finally, any state with a just cause that justifies violence, and which avoids war crimes, seems to be fairly legally justified. (Of course individual crimes may occur. What is important is they are not policy and they are punished.)
Country? | Just cause? (Or at least worth addressing) | The cause could possibly justify violence? | Attacks random civilians? | |
Israel | YES | YES | YES | NO |
The British in Northern Ireland | YES | YES | YES | NO |
The Allies in Iraq | YES | YES | YES | NO |
The Allies in Afghanistan | YES | YES | YES | NO |
So if the word "terrorism" is used for all non-state rebels, then it is not a very useful word. You cannot just condemn all internal rebellions against the state, no matter what the state is like or no matter what the rebellion is like.
This is not a War on "Terrorism". It is a War on Islamism.