Classical physicalism, which is the doctrine in which the physical world is taken to be the only real world, has not provided a plausible account of consciousness. Consciousness experience is as mysterious as it is familiar. This is because although we feel consciousness as the most direct experience, we can ever have but we cannot describe it with an objective viewpoint. It means we cannot account it with any other things we used to interpret other natural events. Here we should differentiate between brain activities, that we can know about them objectively, and consciousness as a first-personal and subjective experience.
David Chalmers introduces ‘easy problem’ and ‘hard problem’ to clarify the distinction between knowing ‘how human brain works’, and ‘what consciousness is like of.’ Easy problems are those that are associated with the human cognitive system and its objective mechanisms. Knowing how does the brain recognise and perceive the difference between various stimuli, and how the brain controls the behaviour by integrating information from multiple sources lies under easy problem category. Easy problems are challenging in physics, biology, neurology, and psychology, but all of these problems are expected to be answered using the current laws of the previously mentioned sciences. (Chalmers 1995)
However, the mystery is laid under the hard problem: how some objective physical processes lead to the subjective experience of consciousness? How the inner aspect of our feelings, perceptions, and thoughts can be arisen from and accounted with physical phenomena? Here there is a vivid distinction between all of what we can objectively study about the mind and its physical mechanisms and the mysterious phenomena we call it consciousness.
Several thought experiments have been coined to illustrate the difference between these two realms of studying the mind. One of them is the “isolated neuroscientist in a black-and-white room” that has been introduced to challenge the physicalistic view. This thought experiment - devised by Frank Jackson, an Australian philosopher – characterises a neuroscientist, Mary, who in the 23rd century knows well about brain processes, colour vision, and its corresponding processes in the brain. However, she has lived in a black-and-white room for the whole of her life. Therefore, she has never seen any colour except black and white. It means she knows almost everything about the physics of colour vision, and she knows the name of each colour based on their respective wavelength - easy problems. However, she has no subjective experience of colours. She does not know what it is like to see a colour such as purple, and more importantly she cannot deduce this experience from knowing the physics and mechanisms of the colour vision in the mind. (Chalmers 1995)
There are various philosophical implications of this though experiment, and of similar experiments as well. One of its most important ones is that this experiment may disprove physicalism because there is a phenomenon – here, a subjective experience such as consciousness – that is not interpretable by and deduced from knowing physical laws and mechanisms, or at least with the physical laws and mechanisms we know so far. Furthermore, it may resurrect the concept of ‘dualism’: that there is an aspect of ‘me’ that is not incorporated into my physical body. These two implications are not mutually exclusive. It means if we disprove physicalism we need to replace some idea with that which is capable of interpreting the finding of this experiment. In this case, that idea can be ‘dualism’. So I do not think that ‘isolated neuroscientist in a black-and-white room’ can support an argument to approve dualism. (Descartes 2008)
Regarding physicalism and dualism, at least two approaches can be adopted. First, one can accept these sort of thought experiments as some supports for ‘substance dualism’ somehow in the similar way that Descartes did in Meditations on First Philosophy. However, I, regardless of discussing the ‘truth’ behind such an interpretation, prefer to search for a physicalistic account that can justify the findings and implications of these experiments by physicalism and here is where the second approach emerges. In other words, there are some thought experiments such as ‘isolated neuroscientist in a black-and-white room’ that possibly can disprove or at least challenge physicalism. However, as long as our new findings can be fit in the big picture that we have already - even if some modifications are required – it is preferable to read the results in the light of the current ‘paradigm’. It means if we can modify the physicalism to be capable of digesting the implications of these experiments then it has to be our first choice. This approach is aligned with what Thomas Kuhn developed about ‘paradigm’ and ‘paradigm shift’ in his landmark work ‘The Structure of Scientific Revolutions’. (Kuhn 1996)
In my view, David Chalmers has followed this approach. He instead of disproving physicalism completely proposed that conscious experience can be considered as of the basic and fundamental features of the world, similar to space-time, electromagnetic charge, and mass. By suggesting this ‘radical’ idea, he tries to reconcile physicalism and dualism under the umbrella of ‘property dualism’ and ‘extended physicalism’. Property dualism implies that there are only physical substances in the world, but some physical substances can have nonphysical properties. This contrasts with Descartes, who is a substance dualist and believed in the separation between physical and nonphysical substances. Phenomenal properties are not physical according to Chalmers, though, causal closure of the physical applies to all physical things and causes.
To conclude, although thought experiments like ‘isolated neuroscientist in in a black-and-white room’ may challenge physicalism as physics laws cannot justify how some objective mechanisms in brain provide a subjective quale, but it is not a strong support for dualism, or at least ‘substance dualism’. To fit the implications of such experiments in the current paradigm of physicalism – as Chalmers proposed – consciousness can be introduced as one of the basic and fundamental features of the world like mass and electromagnetic.
Chalmers, David J. 1995. "The Puzzle of Conscious Experience." Scientific American December 1995:80-86.
Descartes, René, and Michael Moriarty. Meditations on First Philosophy with Selections from the Objections and Replies. Oxford: Oxford University Press, 2008.
Kuhn, Thomas S. 1996. The Structure of Scientific Revolutions. 3rd ed. ed. Chicago, IL: Chicago, IL : University of Chicago Press.