The paper examines the content of epistemic and ontological beliefs among scientists. I take the assumption of the sociology of knowledge that the notion of objectivity is culturally and socially shared and what we believe the truth is depends on the collectively shared socio-cultural cognitive convention. Scientific knowledge is socially and culturally rooted and the notion of truth and objectivity must be treated as expressions of the patterns of culture. This applies also to science and scientific knowledge. The paper provides the results of empirical research which suggest that while the majority of the examined sample adopts views of realists and regards science as objective and trustworthy knowledge, there is still a substantial minority who holds sceptical views on scientific knowledge and cognition. The field in science influences the beliefs in objectivity: those who work in experimental field are more sceptical, whereas those who are theorists are less doubtful about the objectivity of science. Interestingly, the majority of scientists in the sample acknowledges the influence of social factors on scientific knowledge, and yet it does not alter their beliefs in the objectivity of science. The notion of “the thinking-style” introduced by Ludwik Fleck is used to explain the differentiation in epistemic and ontological beliefs about science. It comprises socially accepted schemes of explanation and types of reasoning which are typical for a particular field of science.