Philosophers agree that an important part of our knowledge is acquired via testimony. One of the main objectives of social epistemology is therefore to specify the conditions under which a hearer is justified in accepting a proposition stated by a source. Non-reductionists, who think that testimony could be considered as an a priori source of knowledge, as well as reductionists, who think that another type of justification has to be added to testimony, share a common conception about children development. Non-reductionists (...) believe that infants and children are fundamentally gullible and their gullibility could be seen as an example for justifying testimony, while reductionists believe that this gullibility is merely an exception that should be taken into account. The objective of this paper is to review contemporary literature in developmental psychology providing empirical grounds likely to clarify this philosophical debate. What emerges from current research is a more elaborated vision of children’s attitude toward testimony. Even at a very young age, children do not blindly swallow information coming from testimony; doubtful or contradictory information is automatically screened by their cognitive system. Even if they are unable to give positive reasons for the acceptance of a given testimony, young children are not gullible. Such empirical findings tend to call into question the radical opposition between reductionism and non-reductionism. (shrink)