 [IHT] is a collection of arguments for both the validity and invalidity of spurious inferences. Typically, the pro-arguments construe them as instances of formal inference rules (bona et formalis), the contra-arguments argue that they are not valid (non valet), and the resolutions show that the inference under scrutiny is not a genuine instance of such a rule. This method presupposes that deductive validity is ultimately truth-preservation (an inference is valid if its consequent cannot be false while its antecedent is true or if its antecedent is incompatible with the negation of the consequent) ([IHT] arg. 6). The criterion is that it is not possible to present a counterexample, i.e., a possible (obligational) situation (casu possibili posito) verifying the antecedent and falsifying the consequent ([IHT] arg. 2). The method also presupposes that the underlying inference rules are assumed to be legitimate but misapplied in such sophisms as to require elucidation, and not revision. The treatise is mostly concerned with the analysis of logical form (expositio) of sentences containing operators (officialia) such as “only”, “nothing but”, “begins”, “ceases”, etc., with a few applications of modal and epistemic logic.