The Collaborative International Dictionary of English v.0.48:

Casuistry \Cas"u*ist*ry\, a.
   1. The science or doctrine of dealing with cases of
      conscience, of resolving questions of right or wrong in
      conduct, or determining the lawfulness or unlawfulness of
      what a man may do by rules and principles drawn from the
      Scriptures, from the laws of society or the church, or
      from equity and natural reason; the application of general
      moral rules to particular cases.
      [1913 Webster]

            The consideration of these nice and puzzling
            question in the science of ethics has given rise, in
            modern times, to a particular department of it,
            distinguished by the title of casuistry. --Stewart.
      [1913 Webster]

            Casuistry in the science of cases (i.e., oblique
            deflections from the general rule).   --De Quincey.
      [1913 Webster]

   2. Sophistical, equivocal, or false reasoning or teaching in
      regard to duties, obligations, and morals.
      [1913 Webster]

WordNet (r) 3.0 (2006):

casuistry
    n 1: argumentation that is specious or excessively subtle and
         intended to be misleading
    2: moral philosophy based on the application of general ethical
       principles to resolve moral dilemmas

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "casuistry":
   Christian ethics, Stoicism, aesthetics, altruistic ethics,
   apologetics, apologia, apology, apparent soundness, aretaics,
   argument, argumentation, axiology, bicker, bickering,
   categorical imperative, circularity, comparative ethics,
   contention, controversy, cosmology, crossed fingers, deception,
   deceptiveness, defense, delusion, deontology, disingenuousness,
   disputation, dispute, distortion, egoistic ethics, empiricism,
   emptiness, epistemology, equivocalness, equivocation,
   ethical formalism, ethical philosophy, ethics, ethology,
   ethonomics, eudaemonics, evasive reasoning, evolutionism,
   fallaciousness, fallacy, first philosophy, flyting, gnosiology,
   golden rule, hassle, hedonism, hollow mockery, hollowness, hubbub,
   insincerity, intuitionism, jesuitism, jesuitry, litigation, logic,
   logomachy, mental philosophy, metaphysics, misapplication, mockery,
   moral philosophy, mystification, obfuscation, obscurantism,
   ontology, oversubtlety, paper war, passage of arms, perfectionism,
   perversion, phenomenology, philosophastry, philosophic doctrine,
   philosophic system, philosophic theory, philosophical inquiry,
   philosophical speculation, philosophism, philosophy, plausibility,
   plausibleness, polemic, polemics, rationalization, rhubarb,
   school of philosophy, school of thought, science of being, set-to,
   situation ethics, sophism, sophistical reasoning, sophistication,
   sophistry, special pleading, speciosity, specious reasoning,
   speciousness, spuriousness, subtlety, theory of beauty,
   theory of knowledge, tongue in cheek, uncandidness, uncandor,
   unfrankness, utilitarianism, value theory, verbal engagement,
   vicious circle, vicious reasoning, war of words, wrangling