Origin of the ‘hard problem’
The hard problem of consciousness was first proposed by philosopher of mind David Chalmers (1995). It concerns how the physical phenomena of neural firings relates to subjective experience.
The hard problem
In the characterization of the “Hard Problem” Chalmers proposes that there is not yet any known causal mechanism or connection between the phenomena of a neuron firing and any subjective experience we have (the qualitative experience or qualia).
The main questions we have yet to answer are:
- why consciousness feels the way it does, and
- why it feels like anything in the first place
For there to be a how, we need to find a direct causal link between a firing neuron and the resulting nonphysical qualia.
For instance, a neurosurgeon can probe specific parts of the brain that cause us to experience certain feelings or reactions. We might feel water running on our hands when the neurosurgeon touches a specific location on the brain.
This, in essence, is like the mind/body problem, brought about by Descartes: how an immaterial entity like the mind is connected to a material body. How any particular qualitative experience “feels” is in no way directly or causally explainable in terms of any physical mechanism.
Related topics
We cannot determine that something is truly conscious just by investigating matter. This is best exemplified by the concept of a philosophical zombie. A robot lacking consciousness can appear to be conscious or sentient, but in fact have no internal experience at all.
A further related question is “can AI system with no ‘body’ or ‘mind’ be conscious?” If so, how can we explain what it would be like?
The hard problem, digested
The hard problem of consciousness is a question of relating physical phenomena to mental and subjective phenomena that produce qualitative experience. Unfortunately, a coherent link has not yet been found between the two.
We need a causal mechanism that would link the two, but this has not yet been determined, and it may never be, given the limitations of science. An explanation might require a more comprehensive approach than just the observation of empirical phenomena, such as accompanying explanations from theology.
Paradoxes and Unsolvables 