Donald Trump, an ongoing eruption of self-refuting statements (“I’m a very stable genius” with “a very good brain”), is adding self-impeachment to his repertoire. Spiraling downward in a tightening gyre, his increasingly unhinged public performances (Google the one with Finland’s dumbfounded president looking on) are as alarming as they are embarrassing. His decision regarding Syria and the Kurds was made so flippantly that it has stirred faint flickers of thinking among Congress’ vegetative Republicans.