Logic & Philosophy of Science Colloquium

Abstract:

I distinguish our inferential practice, the rules of correct inference, the facts of logic, and so on from our discussions about them. I call the former(lowercase) "logic", the latter (uppercase) "LOGIC". Although LOGICIANS may discover, revise or invent the LAWS OF LOGIC, and think about logic systematically, practitioners of inference generally do not. Thus I separate questions about revising our inferential practice (revising our logic) from those about revising LOGIC.

My focus in this paper is on revising (lower case) logic. In the recent literature one finds a family of objections that seem to show that revisions of logic, if any, must be quite minimal. By tradition logic is a branch of methodology. So revising logic entails revising methodology. In view of this, I treat revising logic as a special case of revising methodology. Methodology, I take it, is a system of norms that govern our scientific practice (and perhaps our epistemic practice more generally). The worry about revising logic is a special case of the worry about revising some methodological norms while working within the very system of norms to which they belong.

I deny that revising methodological and other norms comes about through acquiring normative knowledge. However, revising can arise through normative argument which can lead us to change our values, goals, and priorities. But sometimes we change our values, goals or priorities in an unreflective response to changes in our circumstances. This observation is the key to my response to the objection that we cannot revise logic (since our deliberations will presuppose logic).

How then might we revise (lower case) logic? Just as speakers of a language go about their linguistic business without consulting the rules of its grammar, we freely make inferences without asking ourselves whether they follow the rules of (our) logic.

Inference making is a social enterprise stabilized by the acquiescence, approval and disapproval of our fellows. Just as we carry out this practice largely without thinking, we also revise it largely without thinking. We simply no longer accept specific inferential connections or, more frequently, we recognize new ones. Like changes in a language certain inferential practices may slowly and quietly become obsolete and new ones may unceremoniously evolve.