This paper defines a university teacher's 'duty to explain' as a way of developing student autonomy. This builds on the idea that in other professions, such as medicine or law, there is a duty of care towards the client to explain the full facts and risks to a patient or client. The university teacher has a similar duty towards the student to explain all perspectives and to problematise claims to knowledge. This approach makes it possible for the student, rather than the teacher, to be the person who evaluates claims to knowledge. The duty to explain is a more a positive way of understanding that the teacher should not indoctrinate the student but instead open up a range of interpretations for them to choose from. This duty also provides a defence of the role of the social sciences in society especially in contexts where academic freedom is weakly established or under pressure.