Much of Charles Ives’ music is built around the art of seemingly chaotic juxtaposition, with many things happening side by side and all at once. But the composer’s Fourth Symphony, which got a gloriously gut-punching performance on Thursday afternoon from Michael Tilson Thomas and the San Francisco Symphony, takes that principle to a meta level. In this explosive stewpot of philosophy, religion, literature and circus showmanship, simultaneity is just one of many techniques the composer draws on to make his points.