Casuistically is an adverb that refers to the use of clever but flawed reasoning to justify a given position or action. Some possible synonyms for this term include sophistically, speciously, fallaciously, misleadingly, falsely, deceptively, and disingenuously. Each of these words implies a certain level of dishonesty or intellectual dishonesty in the way that an argument or justification is presented. While they may be used in different contexts, they all suggest that the speaker or writer is not being entirely truthful or is using flawed reasoning to manipulate the listener or reader. In any case, it is important to be aware of these synonyms when encountering arguments that seem too good to be true.