Let's NOT sacrifice a bull to Zeus.
I really didn't want to write about the London Underground bombings, because, for all practical purposes, I've built up a tolerance to these disasters.
In a twisted sense, terrorist attacks have taken the place of natural disasters, because just as in the pre-scientific era, an earthquake would have people scrambling to find a cause, i.e. any action of them that would have displeased the gods, so as to refrain from doing that and prevent further displeasure of the gods, terrorist attacks yield some highly tenuous or even irrational theories as to what caused them.
Not caused, in the sense of people placing explosives on public transport, mind you, but caused in the sense of, just as the gods of yore, our actions displeasing the people placing bombs. As these, for obvious reasons, prefer to remain anonymous, a variety of these "displeasing acts" circulate.
However, while we can be certain that suggesting "we should sacrifice a bull to Zeus", or even following up on that, will have zero effect on the occurence of the next earthquake, the same can't be said for terrorist acts, because we can't rule out that there are people out there wanting to kill us, and just waiting for an excuse. We should not provide them with excuses, because that might cause another attack.
Once we acknowledge there is no magic bullet to prevent terrorist attacks, it's a lot easier to start treating them as other natural disasters, with law enforcement playing the parts of scientists or engineers in the domains of prevention, damage limitation and data gathering.
Terrorism is here to stay, the least we should manage is a sane response.