How Does Critique Become Effective?

Critique has been the site of a conflict from the time of its origins: the conflict over the proper relation between theory and practice. Must critique protect its fundamental separation from practice, in order to guard against the intrusion of particular interests into what ought to be a realm of rational deliberation? In this case, critique would precede and direct practice. Or, in contrast, does practice precede and make possible the endeavor of critique, by providing, through the struggles it wages, understood as so many experiments and tests, the information without which critique becomes an empty or, worse, an apologetic exercise?