The ‘hard problem of consciousness’ (HPC) as originally stated by David Chalmers in The Conscious Mind (1996) is the problem of explaining how experience is possible. How is any experience, anywhere in the universe, possible? From the perspective of the HPC, a single experience of a flash of light is as mysterious as a full human experience of a summer’s day or the most profound mystical experience of the most enlightened monk. 

There are three going responses to the hard problem that reflect three different ideas about experience:

1.  The possibility of experience (i.e. consciousness) is derived or emergent from something else. The ‘something else’ could be a physical property like quantum entanglement, a general systems property like complexity, a computational property like metaprocessing, a biological property like life, a neuroarchitectural property like having a ‘global neuronal workspace’.

2.  Consciousness is not derived but rather fundamental. However, only some entities have it, i.e. only some entities have experiences. It doesn’t matter how often they have experiences or what kind they have, just that they have some experiences sometimes.

3.  Consciousness is not derived but fundamental and all entities have it.  Again, it doesn’t matter how often or what kinds.