Refusing to join AI in aggressive war - why the penality?

[KaiserJohanHome]

I can understand that you have to honor alliances in a defensive war, but in a aggressive war? And also it seems to have just the same penalities when you decline as if when you decline a defensive war. Why on earth is this? Surely this must be a bug?

 

[Peter Ebbesen]

Alliances in EU4 are not defensive - they are treaties of mutual assistance in case of war. Hence it is entirely appropriate that the same penalties apply.

 

[LordOfBlood]

Alliances do like marriages, you must obey them in both good and bad times

 

[Tiaexz]

Depends on the war as well, different ones have different prestige hits, or even stability. I think defensive incurs a harsher penalty, I believe.