The Logic of Conceivability (LoC) project focuses on the logic of mental simulation: how we reason when we consider hypothetical scenarios and wonder what would follow if they happened. Our mind represents non-actual scenarios to extract information from them: since we cannot experience beforehand which situations are or will be actual, we explore them in our imagination, leaving our perceptions offline: ‘What will happen if there's a disorderly Brexit?’; 'What will I do if I cannot repay my mortgage?'. The cognitive importance of this activity is hard to overestimate.
But what is its logic? The orthodox logical treatment of representational mental states like conceiving, imagining, and believing, comes from modal logic’s so-called 'possible worlds semantics': the modal analysis of knowledge, belief, information, provided by modal logic, was taken up by philosophy, linguistics, and Artificial Intelligence. However, the approach faces problems. By systematically addressing them, the LoC project aims at yielding a paradigm shift in our understanding of the logic of human suppositional thought.
One purely logical problem is that mainstream epistemic logics model cognitive agents as 'logically omniscient', thus as disconnected from the reality of human, fallible minds. The cognitive agents represented in this way conceive (imagine, believe, etc.) all the logical consequences of what they conceive (etc.). They know all logical truths, and are perfectly consistent in their beliefs. Real people are not like that.
One major philosophical problem concerns the entailment from conceivability to possibility, e.g. in ‘thought experiments’ of theoretical philosophy: how does conceiving a scenario give evidence of its possibility? Imagination seems to be totally unconstrained; but if we can imagine whatever we like after supposing an initial scenario, e.g. via free association of ideas, then such exercises seem to give us no hints on what is or is not likely to happen, on what may and may not take place.
LoC addresses such issues via the techniques of non-classical modal logics. One aim is to make logically precise the distinction, taken from cognitive psychology, between Fast Thinking (associative, context-sensitive) and Slow Thinking (rule-based, analytic). Another is to show how logical omniscience is avoided, and evidence of possibility is achieved, in different manners in the Fast and Slow Way. Finally, the LoC project aims at connecting the abstract theoretical modelling of cognitive agents performed within mathematical logic with the reality of empirical results from the psychology of reasoning.
Based at the Department of Philosophy of the University of St Andrews, and at the Institute for Logic, Language and Computation of the University of Amsterdam, and advised by a Board of researchers from Europe, the US, and Australia, LoC is delivering high-impact outputs for top peer-reviewed journals and publishers, and knowledge dissemination results for non-specialists.
