Reflective belief revision before the age of reason

Young children can revise beliefs in light of new evidence, yet some philosophers argue that this is not true rationality. They define rationality as the capacity to reflect on and re-evaluate one's reasons for beliefs, tying it to language and proposing that it emerges only around the so-called "age of reason" (age 6). In challenge to this, we tested whether children aged 3 to 6 (N = 93) were capable of a basic form of reflective responsiveness to reasons: acquiring and responding to an undermining defeater-evidence that challenges the grounds for a belief-through exposure to overriding defeaters. In each trial, before choosing where to search, children observed a Reliable informant (100% accurate) and an Unreliable informant (50% accurate, 50% misleading) indicating one of two reward locations. Each misleading trial served as an overriding defeater, directly contradicting children's initial belief about the reward location. Age and language predicted children's tendency to follow the Reliable over the Unreliable informant suggesting they may have acquired an undermining defeater related to informant reliability. However, neither age nor language predicted preferences when the informants were pitted against each other in a new context. These findings suggest some basic capacity for reflective responsiveness to reasons may emerge earlier than the "age of reason", more independently of language than some philosophical accounts have assumed, and may be grounded in capacities (overriding defeaters) already present at the unreflective level.