The "hard problem of consciousness" is a term coined by the philosopher David Chalmers in 1995. It refers to the challenge of explaining why and how physical processes in the brain give rise to the subjective experience of being conscious. While we can observe and measure physical phenomena, like brain activity associated with conscious states (often referred to as the "easy problems" because, in principle, they can be addressed with our standard scientific methods), the hard problem addresses why and how these processes are accompanied by conscious experience.
To break it down:
- Easy Problems: These involve explaining the ability to discriminate, integrate information, report mental states, focus attention, etc. These are considered "easy" not because they are trivial or have already been solved, but because they are amenable to investigation through standard scientific methods, i.e., it’s relatively straightforward to imagine experiments or empirical observations that can help us understand these phenomena.
- Hard Problem: This involves explaining why and how physical processes in the brain give rise to the experience of being conscious. Why do we have subjective experiences at all, and why do they manifest in the particular way that they do?
Chalmers describes subjective experiences as "qualia" – the internal, subjective component of sensory experiences. For example, we might explain the wavelength of light associated with the color blue, the way our eyes perceive it, and the way our brain processes those signals (easy problems), but explaining why we have the subjective experience of "blue" is more challenging (the hard problem).
The hard problem of consciousness is tough because it's unclear how physical processes (like neural activity) can give rise to subjective experiences (like feeling pain or seeing the color red). Moreover, even a complete knowledge of the physical processes in the brain might not give us insight into why certain physical states are conscious while others are not.
It’s worth noting that while the term "hard problem" has been quite influential, not all scientists and philosophers believe that the hard problem is genuinely "hard" or even that it is a valid philosophical issue. Some consider it more of a linguistic or conceptual confusion than a genuine scientific or philosophical problem.