Remember that no theorist has all knowledge and no one is without blind spots. For most, their writings preceded the full testing of their ideas in real situations and often the corrective influence of alternative points of view. The theorists you will study do not have the advantage of what you know from experience or from advances made since they wrote. You have at your disposal an array of methodologies and new perspectives in social science research not available to earlier generations of scholars. Compared with earlier thinkers, scholars now are much more sensitive to differences in approaches to meaning taken by different genders and ethnicities.
Contemporary writers are more hesitant to make claims for all people for all times.
They increasingly realize that their own cultural contexts and personal value systems help determine what they study, how they study it, and what conclusions they might put forward. On these grounds, not only may you criticize the ideas of others, but you must do so if our collective knowledge is to continue to grow and be trustworthy. Turn your critical analysis not only on the writings of others, but on your own work as a scholar and as a practitioner as well. This requires a good deal of research unhurried reflection along with a measure of the kind of common sense that grows out of experience. Put your imagination to work for you.