On The DMZ: Matt says it’s time for the GOP to engage in some creative self-destruction. Are House Republicans crazy to threaten a government shutdown to defund Obamacare? Matt says many Republicans have embraced a revolutionary mindset, and he expects to see the party follow a doomed mission. Bill and Matt debate whether Obama botched his response to the Navy Yard mass shooting. Is the president’s second term shaping up to be a failure? Plus: Evaluating Peter Beinart’s argument that Millennials are poised to move the country sharply to the left.