The Interaction of ‘If’ and ‘Would’

The chapter argues that ‘would’ is associated with a suppositional heuristic analogous to that for ‘if’ but sensitive to the contextual restriction on ‘would’. This heuristic has structurally analogous consequences to those for ‘would’; in particular, it generates the appearance that ‘would’ commutes with negation, and correspondingly that counterfactuals obey the principles of Conditional Excluded Middle (CEM) and Conditional Non-Contradiction (CNC). However, to play its central cognitive role properly, ‘would’ must be able to generalize over more than one world at a time, thereby invalidating CEM, which is thus an artefact of the heuristics (as is CNC). Connections between ‘would’, ‘will’, ‘might’, and ‘not’ are explored. In particular, the relation between ‘will’ and ‘would’ corresponds to the relation between online prediction and offline imagination.