The human capacity for rational decisions hinges on modal judgment: the discernment of what could, has to, or cannot happen. This ability was proposed to be a late outcome of human cognitive development, contingent on the mastery of linguistic structures. Here, we show that preschool-age children are capable of sophisticated forms of modal…

When determining what others know, we intuitively consider not only whether they succeed but also their probability of success in the absence of knowledge (e.g., random guessing). Across three experiments (n = 240 North American 4-6-year-olds, data collected between 2020-2023) we find that 4-year-olds understand that tasks with a lower probability…

Children often say that possible events are impossible, and only gradually come to see these events as possible. For instance, they often deny that people could do unusual things, like own a pet peacock, or immoral things, like stealing or lying. These possibility denials are surprising. For instance, children have first-hand experience with the…