MacNelly is one of the few contemporary political cartoonists who can use humor to accentuate, not vitiate, his points.
-- Richard E. Marschall, "The Century In Political Cartoons", Columbia Journalism Review, May/June 1999
It seems churlish to say of a book that is beautifully written, richly allusive, learned, elegant, Proustian in tone and mode, that precisely these qualities vitiate its ostensible purpose, distracting attention from the subject and focusing it upon the very gifted author.
-- Gertrude Himmelfarb, "A Man's Own Household His Enemies", Commentary, July 1999
Whatever a "real contradiction" might be, "apparent contradictions" are quite sufficient to vitiate a doctrine of biblical authority that is based on the supposedly apparent reading of the text.
-- Robert M. Price, "The Psychology of Biblicism", Humanist, May 2001
Vitiate comes from Latin vitiare, from vitium, fault. It is related to vice (a moral failing or fault), which comes from vitium via French.