Like propositions, an assumption is a point of view, or possibly a fact, but this time, it is widely accepted, and not offered for discussion. This does not mean, however, that you cannot challenge received wisdom; it might be productive to do so. For example, questions prefaced by a quotation are common in exam contexts. Sometimes the quotation is offered as an example of the kind of issue the title raises, in order to validate it. However, you might consider contesting whether the example is in fact a representative or appropriate example of the issue under discussion.
As when working with propositions, you should be alert to the extent to which you can challenge the assumptions contained within the title. Test your own arguments rigourously to be sure that you are not putting forward an untenable position.