After the attack on Charlie Hebdo, certain liberals joined conservatives in declaring that the killer was Islamic extremism. Any suggestion of Western culpability would be inaccurate, if not immoral.

“The murders today in Paris are not a result of France’s failure to assimilate two generations of Muslim immigrants from its former colonies,” wrote George Packer.

They’re not about French military action against the Islamic State in the Middle East, or the American invasion of Iraq before that. They’re not part of some general wave of nihilistic violence in the economically depressed, socially atomized, morally hollow West — the Paris version of Newtown or Oslo. Least of all should they be “understood” as reactions to disrespect for religion on the part of irresponsible cartoonists . . . They are only the latest blows delivered by an ideology that has sought to achieve power through terror for decades.