The argument is familiar. It begins with an honest account of the mystery of consciousness and how there is, as of yet, no adequate or complete scientific explanation for how subjective experience of the material world can arise from the material world. The subjective experience of seeing the color red, for example, is very different from the scientific accounts of wavelengths of light or electrochemical activity in the brain.
It is then pointed out that there is no direct external evidence of consciousness, and that only one’s own consciousness can be known with any degree of certainty. The problem of the “philosophical zombie,” however improbable, is nevertheless unnerving as there is no way to definitively prove that consciousness is driving the behavior of others. Consciousness is therefore one of the deepest mysteries in the universe.