Three-Year-Old Children Can Reason via Disjunctive Syllogism

Logical reasoning is fundamental for human cognition, yet its developmental andevolutionary origins remain unknown. A central debate concerns whether logical reasoningdepends on natural language. One form of logical reasoning widely studied in comparative anddevelopmental psychology is reasoning via disjunctive syllogism (A OR B, NOT A,THEREFORE B). Previous studies examining disjunctive syllogism in non-human animals,infants, and young children have produced mixed results (Cesana-Arlotti et al., 2018;Engelmann et al., 2023a; Ferrigno et al., 2021; Gautam et al., 2021; Mody & Carey, 2016),prompting questions about the developmental trajectory of this reasoning ability. In twoexperiments, we investigated whether 3-year-old children can reason using disjunctive syllogism.Children (N = 73) participated in a gumball game where they helped an experimenter obtain adesired gumball. To succeed, they needed to use disjunctive syllogism to determine which of twogumball machines must or might produce the desired gumball. Results showed that childrenreliably chose the correct machine. These findings indicate that 3-year-olds can reason viadisjunctive syllogism and this reasoning ability develops before children comprehend words forlogical concepts.