 We encounter a similar mixture of psychologistic and anti-psychologistic motifs also as we turn to Mill’s views on how the logician ought to justify logical precepts and principles. For Mill, we specify the rules of deductive inference by identifying the valid forms of the syllogism (1843, 168). And validity is explained by the formula ‘if the premises are true, the conclusion must inevitably be so’ (1843, 166). ‘Good inferences’ have an connection to truth: ‘A reasoning, to be rightly framed, must conduct to a true conclusion’ (1865, 365). And hence