Primary among the arguments against
Utilitarianism are that the doctrine ignores/eliminates the concepts of
individual rights and
justice. (Concepts which, oddly enough, are held dear by the countries this philosophy flourishes in.) Put plainly, a strict
classical Utilitarian would have no qualms about sacrificing a single
innocent person to serve the greater happiness of a larger number of
people. Or, on a smaller
scale, say a
peeping tom took pictures of a naked woman without her knowing. He consequently derives a great deal of enjoyment, whereas she, all unawares, is completely
unaffected. By Utilitarian doctrine, this action was perfectly morally sound.
Thus, in plain terms, Utilitarianism can be used to justify actions that commonsense morality tells us are wrong.