Belief in the reasonableness of others: stability and responsiveness to electoral shock

An improved survey measure for the belief in the reasonableness of others - the Faith in Reason scale - is tested on a representative sample of US voters. This measure shows there is a wide natural variation in responses, including across the political spectrum, and that the measure has a moderate test-retest stability after a two week delay. The 2024 US presidential election provides an opportunity for a planned quasi-experimental longitudinal investigation, demonstrating that the measure is responsive to events. Those disappointed by the election outcome reported a lowered belief in the reasonableness of others following the election. The post-election difference between those supporting the winning and losing candidates was large (Cohen's d = 0.77). Those whose confidence was highest in the opposite outcome, as demonstrated by willingness to wager on the size of their bonus payment for participation, demonstrated the largest reduction in their faith in reason, post-election.