Asked to clarify his position Hume remarked that simply because every person who has jumped out of a window in the past has fallen downward does not imply that the next person to jump out a window will react similarly. I distinguish my philosophical from my practical self. Here is the point. In Intermediate Price Theory be your philosophical self. While casual empiricism may suggest that man is not a purely rational being it is nevertheless an assumption that will be made about human behavior throughout the course.
Deductive analysis requires that some set of assumptions be made.
The essence of microeconomic theory is the logical analysis of a certain set of hypotheses concerning the world. Once the world is described, obviously in a simplified manner, the remainder of the analysis is logical deduction after logical deduction. The problem you face is to force yourself to think in this manner. Once you have taken econometrics you can empirically test the validity of the models you will learn about in this class. But for the time being, spend your energy trying to understand the theoretical models.