While you may see a theory as an absolute, such as the theory of gravity or the theory of relativity, it is actually a changing phenomenon, especially in the soft or social sciences. Theories are developed based on what is observed or experienced, often times in the real world. In other words, a theory may have no additional backing other than an educated guess or a hunch about a relationship. For example, while teaching a college course in research, I notice that non-traditional students tend to be more involved in class lectures and perform better on class exams than traditional students. My theory, then, could be that older students are more dedicated to their education than younger students.
At this point, however, I have noticed only a trend within a single class that may or may not exist. I have developed a theory based on my observations and this theory, at least at this point, has no practical applications. Most theories are less concerned with application and more concerned with explanations. For example, I could assume, based on my observations, that older students have witnessed the importance of education through their work and interactions with others. With this explanation, I now have a theoretical cause and effect relationship: Students who have had prior experience in the workforce are more dedicated to their education than students who have not had this experience.
Before moving beyond this point it is always wise to do a literature review on your topic and areas related to your topic. Results from this search will likely help you determine how to proceed with your research. If, for example, you find that several studies have already been completed on this topic with similar results, doing yet another experiment may add little to what is already known. If this is the case, you would need to rethink your ideas and perhaps replicate the previous research using a different type of subject or a different situation or you may choose to scrap the study all together.