FOR THE LAST several years, David Ellwood has spent much of his time debunking the work of the neoconservatives’ favorite welfare expert, Charles Murray. As Ellwood recalls in the preface to his new book, liberal critics of Murray initially fastened on studies by Ellwood and his Harvard colleague, Mary Jo Bane, to rebut Murray’s argument in Losing Ground that welfare tears apart black families and provokes poor women to have babies. Ellwood himself soon joined the fray, repeatedly criticizing Murray’s claims. Yet whenever Ellwood spoke publicly about his findings, he found one troubling response: “People hated welfare no matter what the evidence.”