We experience a wonderful world full of color, tastes, sounds, smells, etc.. However, science tell us that what we believe what's really out there is much different than our experiences. For one thing, the colors that we perceive are not properties of objects, but rather wavelengths of light. Yet, electromagnetic-wavelengths(light) are very different from the sensations of color that we experience.

There is a discrepancy between our sensations of the world, and how the world is. In the world, objects are colorless, tasteless, soundless, odorless, etc.. Yet there are objects with these sensory properties, and if they aren't outside our heads, there is only one other option, namely that the sensory objects are mental objects. From what follows is that there some mental theater going on inside our heads.

One of the problems with this mental theater view of sensation is identifying the one viewer. Who exactly is the privileged "I",the VIP, who gets such prime seats for free? And how do we avoid the homunculus fallacy?