top of page

Philosophy 101: Is the Physical World All that There Is?

Following on from the first philosophy 101 series this second in the 101 series takes a look at the relationship between experience and the physical world. Specifically, a close inspection of the famous thought experiment devised by the Australian philosopher, Frank Jackson in 1982. 'The knowledge Argument'

Philosophers have been debating questions about Qualia and physicalism since time immemorial. The former term relating to individual subjective experiences that are completely unique to a person, and the latter meaning that all things in our physical world, including facts about the human mind, are reducible to physical processes. It is a hotly debated topic and one which fascinates anyone with a curious mind. In the early 1980s, Australian Philosopher Frank Jackson developed a thought experiment intended to question the validity of physicalism.

Philosophe. (n.d.). [Photograph]. Philosophe.

‘The Knowledge Argument’ or ‘Mary’s Room’ as it is sometimes referred to, is a story about a girl who grows up in a monochrome room. All Mary knows about the material world is that all objects appear to be in black and white. However, Mary is a neuroscientist and an expert in colour vision. The scientist has exact knowledge of what happens when the brain experiences colour from the physical processes that take place as soon as the eye receives information and relates back to the brain. For example, Mary knows every single process that occurs in the brain when someone experiences the colour red. But, she has never experienced seeing the colour red. Then, one day, Mary is released from the monochrome world and can now experience the real world like everyone else. Mary can now experience red.

Jackson posits the notion that because Mary, until the release from the monochrome room, was unable to experience seeing red, does the scientist now experience something new by dint of the fact that the girl now has a true experience of physically seeing the colour red? Jackson argues that if the girl does learn something new, then this refutes the idea of physicalism. That there is more to this world than just physical materials. That having conscious subjective experiences go beyond the physical realm of reality. In other words, that physicalism is independent of experience, and therefore, does not offer a full explanation that all things in the world are material.

Greek Philosophy. (n.d.). [Photograph]. Greek Philosophy.


The philosopher, Daniel Dennett argues, that if Mary already truly knew "everything about colour", that knowledge would necessarily include a deep understanding of why and how human neurology causes us to sense the "qualia" of colour. Moreover, that knowledge would include the ability to functionally differentiate between red and other colours. Mary would therefore already know exactly what to expect of seeing red before ever leaving the room. Dennett asserts that functional knowledge is identical to the experience, with no ineffable 'qualia' left over. As a consequence, Dennett concludes that this is not a sound argument for the existence of qualia. Other physicalists believe that ‘Mary’s room’ is not a valid argument against physicalism because the thinking is that Mary does not learn anything new as such, rather, she gains a new skill. She learns of the subjective experiences of others, however, she does not physically learn anything new about seeing red. There is also the school of thought that says that Jackson's argument makes sense on the surface, however, this does not mean that it totally writes off all physicalism. Initially, Jackson was of the belief that the thought experiment demonstrated that there was more to the physical world than just physical processes and materials, though later had a change of mindset. Jackson now believes that the physicalist approach provides a better explanation. The philosopher goes on to explain that experiencing red merely causes different states in the brain to occur like memory and recognition, but nothing new is actually learned. He goes on to draw parallels with patients who suffer from akinetopsia, a condition that affects the brain. It is essentially the lack of perception of the motion of objects. Jackson asserts that if someone is cured of akinetopsia, the surprise at experiencing this is not the fact that anything new is learned about the real world, moreover, that the surprise is at the fact that the brain now allows them to see objects in motion.

Origins of the “Hard Problem” of Consciousness. (2016, August 18). [Illustration]. Origins of the “Hard Problem” of Consciousness.


Very often I find myself switching from one camp to the other, however, I think on balance the physicalist argument does provide a more persuasive line of thinking. On the surface, Jackson's thought experiment sounds perfectly reasonable and logical. If one does not experience a colour or object and one day has those experiences, it seems counter-intuitive to think that nothing new has been learned. But that is to not fully incorporate what the premise of the thought argument is illustrating and asking the reader to consider. If all knowledge, with all the physical processes, are understood before experiencing a particular object, (in this case, red) then it makes good sense that the only things that are learned are the ability to recognize and remember that thing that was known, extensively, before the physical experience. Furthermore, it is worth noting that if one falls on the side of qualia, then one is forced into the corner of accepting the idea of dualism - the idea that the mind is independent of the body or brain. So, for example, the view that a person's soul is a form of dualism. It is not a physical thing. Currently, medical professionals, for instance, would mostly agree that dualism is not a viable viewpoint. Especially if one works in neurology. Of course, there will be some medical professionals who may have religious beliefs but find it quite easy to leave their religious views outside the surgery doors, but I suspect they are in the minority. And needless to say, there will be many who argue that science has not got all the answers. That is true too, though, for me, personally speaking, does not make it a fifty-fifty perfectly balanced argument. The evidence for all things in the real world being purely physical seems heavier than the counter-arguments, but does anyone really know? I am sure this debate will rumble on and on.


  • Lacewing, M. (2008). philosophy for AS. Routledge.


Author Photo

Peter Terrence

Arcadia _ Logo.png


Arcadia, has many categories starting from Literature to Science. If you liked this article and would like to read more, you can subscribe from below or click the bar and discover unique more experiences in our articles in many categories

Let the posts
come to you.

Thanks for submitting!

  • Instagram
  • Twitter
  • LinkedIn
bottom of page