The Bush generations have enriched themselves while impoverishing the presidency.AT THIS point, the policy legacy of George Bush seems pretty well defined by three disparate disasters: Iraq in foreign affairs, Katrina in social welfare, corporate influence over tax, budget and regulatory decisions. As a short-term political consequence, we may avoid another dim-witted Bush in the White House. But what the Bush dynasty has done to presidential campaign science — the protocols by which Americans elect presidents in the modern era — amounts to a political legacy that can haunt the Republic for years to come. We are now enduring the...