We must do something; this is something; therefore we must do it.
Nothing I've read so far proves to me that inaction will have worse consequences than action. The contrary may even be true.
No matter how horrific the Syrian regime's crimes the bombs will fall as they may - no amount of moral outrage will make them any more accurate or their consequences any less unpredictable.
Some seem impervious to this reasoning. They argue that the regime's crimes are horrific, therefore the West must act. They fail to see the giant, gaping gap in the middle of that sentence - what can be done?