Using the prevailing media-logic applied to Bush's counter-terrorism policies such as torture and Guantanamo (i.e., if a country is attacked by Terrorists, its Government then does X, and there are no Terrorist attacks for some period of time thereafter, then that is "proof" that "X stops Terrorism"), I believe these events in Spain constitute proof that the way to stop Terrorism and to keep the citizenry safe is to stop invading and occupying Muslim countries and take accused Terrorists and put them on trial with full due process rights before putting them in cages for life. After all, that's what Spain did, and there's not been another Terrorist attack for five years. Therefore, those policies have kept the Spanish people safe.
I have a special tiger-repelling rock for sale if anyone's interested. I've had this rock in my possession the entire time I've lived in Iowa City and I've never been attacked by a tiger. Thus, I have proof that this amazing rock does indeed ward off tiger attacks. Any takers? (Hat tip: the Simpsons.)