JOSEPH SOBRAN THE LIBERAL THEORY OF CAUSATION WASHINGTON -- Martin Luther King's "dream" has become America's nightmare. Ever since the Civil Rights movement began blaming white Americans for the sufferings of blacks, black crime -- especially black-on-white crime -- has exploded. Whatever King and his ilk intended, black thugs across the country got the message that they could murder, rape and rob with some covert sympathy from black leaders and white liberals. It's high time the black leadership took responsibility for the Willie Hortons they have spawned. If you buy this argument, you should have no trouble buying the argument...