If the question is asking how to do something, and you are interested in a solution using a framework, when it is available, or a generic solution when there isn't a specific solution using the framework, I would use both the tag for the framework, and the language. IMO, this is preferable than asking two questions where one is about using the framework, and one is about the language.
To make an example, if I wanted to know which function I should use in my code, and I am not sure if Drupal has the function I am looking for, I would tag the question with drupal, and php. If I want to know if Drupal has a function that I could use, I would tag the question with drupal. In the latter example, if I tag the question also with php, I would probably get answers about PHP functions, or plain PHP code to use when I am interested in one or more Drupal functions. Who knows PHP could not know Drupal has specific functions, including those functions that extend a PHP function. (See the functions listed in this page, as example.)