In their global warming bill, Sens. John Kerry (D-Mass.) and Barbara Boxer (D-Calif.) have delivered to Congress an incomplete script. It’s like “Hamlet” without the prince. The 821-page aggregation of environmentalist dreams, rhetoric and directives would mandate grants and demonstration projects galore, and set up targets right and left. It would even grant a few unrelated favors, such as authority for cities to set their own mileage standards for taxicabs. (That the bill wouldn’t solve the cabbies’ basic problem of having to buy and insure new hybrids seems not to bother the senators.) The cap-and-trade scheme by which large emitters...