These words refer to over-subtle argumentative techniques that place more emphasis on form than content, often with the intent of misleading or deceiving an audience. Sophistry and sophism both derive from a Greek word for wisdom and relate to the Sophists, a pre-Socratic school of philosophers interested in the logical expression of philosophical truth. In Socrates?day, the name was taken over by paid philosophers who taught logical and rhetorical techniques and were concerned more with persuasive forms of discourse than the search for truth. Thus, both words now indicate false argument intentionally used to deceive. While the difference between the two words is slight, sophistry might be most useful as a generic term, sophism as a reference to specific examples: campaign oratory filled with sophistry ; a statement on taxes that was a sophism pure and simple.

Casuistry has a Christian theological rather than classical Greek background; it refers to the science or doctrine of ambiguous or special cases of conscience, balance against prevailing rules of religion and morality, thus determining questions of moral right and wrong. The reasoning involved in this sort of argument was often so subtle, quibbling and complicated that the word has come to be used with the same pejorative tone that sophistry has acquired. It still applies particularly to disputes about ethics or morals: a politician who has abandoned the casuistry surrounding arguments over capital punishment. Hair-splitting is more specific than these other words in applying to any sort of argumentative discourse in which finicky or petty attention is given to fine points of method or substance in such a way as to lose slight of more significant questions: descending to hair-splitting about side issues whenever his opponent managed to present a convincing statement on the main issue.