 The capacity for modal knowledge can thus be thought of as a byproduct of our capacity for counterfactual thinking. For Williamson counterfactual thinking is largely imaginative thinking. When we assess a given counterfactual, we evaluate the consequent on the supposition of the antecedent by developing the supposition through an imaginative exercise. This typically involves the “offline” application of our cognitive capacities. More precisely, Williamson holds that in imagination we often transpose “online” cognitive skills that are originally developed in perception into corresponding offline cognitive skills (2013).