Epistemology is the philosophy of knowledge. Epistemologists are interested in how and whether we know anything. In sociology there is a discussion about social facts and social constructs and the difference between positivism and interpretivism. Positivists believe that it is possible to establish social facts through objective and scientific research, while interpretivists believe that we cannot objectively establish facts about human behaviour, they will only ever be social constructs, but what we can do is investigate subjective interpretations of behaviour.