At Tuesday night’s presidential debate, Trump was asked about his economic agenda. As we’ve come to expect, he produced an incoherent word salad — a rambling, nonsensical, maniacal aggregate of lies and diversions that offered more evidence of his declining acuity than of anything resembling sane economics. He was only slightly more coherent at his appearance last Thursday at the Economic Club of New York. On both occasions, Trump promised to raise tariffs on virtually all imports. He has said he’ll use the revenue to finance child care, combat inflation, pay for a U.S. sovereign wealth fund, …