Trust Logic, Not Tortoises

I examine Kripke and Padro’s recent result that basic rules of logic - such as universal instantiation - cannot be adopted, and apply this lesson to two extant answers to the Justification Question, i.e. how are basic rules of logic justified? One answer was provided by Carnap’s doctrine of logical conventionalism; another by Quine’s holism. I argue each suffers from adoption-related problems. Having observed requiring explicit acceptance of basic rules guiding our inferential practices led to adoption-related trouble for Carnap and Quine, I then construct two additional answers to the Justification Question that avoid similar trouble. On the first proposal, explicit acceptance of basic rules of logic is weakened to implicit acceptance – regular behavior in accordance with the rule. After arguing this option both avoids Kripke and Padro’s negative result and provides a prima facie plausible answer to the Justification Question, closer inspection reveals the proposal has significant costs. On the second proposal, requiring basic rules of logic be accepted at all is dropped by rejecting these rules have propositional content. Rather, on the model of Michael Devitt’s recent work concerning linguistic competence, basic rules of logic are defended as know-how rather than propositional knowledge. As before, after arguing this option avoids conflict with the negative results of the Adoption Question and offers a prima facie plausible answer to the Justification Question, inspection reveals costs. Nevertheless, it is argued nearly every cost is one shared by the first option, and each is worth paying.I thus provide two ways to answer the Justification Question while respecting the Adoption Question, and argue the second is preferable.