[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