Quantifying belief in the rationality of others: the Faith in Reason scale

What we believe about other people matters. It is not enough that others are trustworthy, reasonable or well-intentioned. Successful coordination, as well as individual wellbeing, benefit when we also perceive others as trustworthy, reasonable or well-intentioned. While standard measures of trust and benevolence exist, there is no standard measure of the generalised belief in the rationality or reasonableness of other people. Here, we present the development and testing of a scale to directly measure this attitude. Using a representative sample of 1869 UK adults, we test dimensionality and consistency of the scale items. We show that the refined, six-item, scale is associated with, but not entirely determined by, generalised trust in other people. Our "Faith in Reason" scale shows large individual differences, but the average tendency is slightly on the side of endorsing, rather than rejecting, sentiments such as "The typical person is often irrational".