The objectively real world may be separate from and indifferent to sense perception, but sense perception isn't indifferent to the objective world. Sense perceptions are caused by an interaction of our sense organs and the world. Surely from repeated patterns of sense perception we can draw some correct inferences about the external world?
I loved Turbo Pascal so much. Wrote my own DOS windowing system. When the object oriented stuff came out,it was mind blowing but still so accessible.