Philosophy is "thinking about thinking." It clarifies our thought process and refines the basic concepts that we use to understand reality.  Like other sciences, it works on problems – it is driven by questions that cannot be answered easily, or that are empirically undecidable. If these questions, like the mind-body problem, cannot be answered (yet?), one may still be able to build a theory that illuminates the problem itself. Philosophy has a system-building function, and it moves between explanation and understanding.  Philosophy often discusses questions that later become fields of scientific inquiry; it is not only a search for causes,  but also for ultimate meaning.

I have compiled a short list of what I consider to be some of the harder philosophical problems – not just plays with definitions, or questions about imaginary concepts, such as whether God exists.