Mathematical argumentation is generally thought to be the paradigm of cogent reasoning. The concept of mathematical proof thus seems to be associated with necessity and enforcement, but not with freedom; however, in various ways a reference to freedom is also needed to understand the phenomenon of mathematical proof, for example, to distinguish it from a merely mechanical functioning. Moreover, without reference to these freedom-related aspects the value of incorporating proofs into the teaching of mathematics lacks an essential aspect of justification. The paper sheds light on some of these aspects and offers a picture of mathematical proof in tension between freedom and enforcement.