This article studies the intuitive epistemologies of university students from two perspectives: their beliefs concerning the nature of knowledge and their beliefs concerning how that knowledge is achieved. We confronted students with a questionnaire in which they had to choose, in a Likert scale, between different epistemological options and afterward we asked them to justify the epistemological positions they had assumed. Results showed that students were epistemologically more sophisticated when they had to select a position than when they had to justify it. Concretely, they choose mainly constructivist beliefs but their justifications were closer to objectivistic positions, showing a kind of “naïve realism” as the epistemological belief from which most students implicitly approach science learning. In fact, our data confirmed that the less instructed students were also the more realists. We compare these results with the data obtained with the same students in two other knowledge domains –moral and social knowledge- in which this trend towards “naïve realism” appears to be less strong. The paper concludes exploring the cognitive and cultural foundations of this intuitive objectivism with regard to the epistemological nature and the acquisition of scientific knowledge, as well as the teaching strategies that should be used in order to improve the complexity of epistemological beliefs in secondary and university students