The Phenomenal Complexity of Consciousness

by Ruby Allen

Ironically, human brains are yet to reach a consensus regarding the definition of their own consciousness. John Searle states that consciousness is simply the “subjective [state] of awareness or sentience” when one is awake.[i] However, I believe this conceptualisation is not adequate to explain how human beings  are aware of the world and what aspects of cognition allow us to develop knowledge and other cognitive abilities.

A prominent thought experiment addressing this issue was posited by Frank Jackson in his article “Epiphenomenal Qualia.”[ii] The experiment includes Mary, a scientist who has never seen colour and must investigate the world within a black and white room. Mary is given all the physical information about colour perception that exists, such as which wavelengths produce certain colours, how these stimulate the retina, and exactly how this causes the central nervous system to react.[iii] The crux of the experiment is this: if Mary is allowed to leave the monochrome room and experience colour perception, will she learn any new information?

Jackson argues that Mary does learn new information upon leaving the room and he develops the Knowledge Argument, which states that conscious experiences involve non-physical properties. Opposingly, physicalists argue that Mary does not learn anything upon leaving the room. Instead, David Lewis proposes the Ability Hypothesis: that experience allows you to gain abilities, such as remembering and imagining, rather than knowledge.[iv]

In this essay, I argue that Mary learns what it is like to see colour when she exits the monochrome room, thus gaining new, non-physical knowledge. Furthermore, physicalists cannot soundly deny the “qualia” of phenomenal experiences (which I define in the following passages) because they misrepresent the distinction between “knowing-that” and “knowing-how.” Finally, if we accept that Mary’s case proves the existence of qualia, we must expand our conceptualisation of consciousness into two distinct levels as proposed by Ned Block: phenomenal consciousness and access-consciousness.[v]

When Mary leaves the black and white room and perceives colour for the first time, it is undeniable that she is undertaking a new experience. Jackson argues that even though she had access to all physical information about colour perception while in the black and white room (P1), Mary learns “something about the world and [her] visual experience of it” when she leaves (P2).[vi] This begs the question: what type of information did she learn? In the Knowledge Argument, P1 and P2 imply the intermediary conclusion that there must be non-physical facts concerning colour vision.[vii] This account considers the intrinsically subjective qualities of phenomenal experience. It could be argued that in the monochrome room, Mary only knew the objective, causal, and physical basis of those qualities, but could not truly understand them.[viii] Therefore, Jackson concludes that not all information is purely physical information. This non-physical information is known as qualia— “intrinsic, consciously accessible, non-representational features of sense-data and other non-physical phenomenal objects that are responsible for their phenomenal character.”[ix] It is clear that leaving the room allows Mary to learn the phenomenal character of colour perception, and thus to truly know all information about colour. I agree with this stance. In my view, it follows logically that in order to truly understand phenomena, one must experience said phenomena.

Physicalists, on the other hand, disagree with the Knowledge Argument and posit that Mary does not learn new information upon leaving the room. Instead, it is argued that the physical information she knows is sufficient for Mary to understand what it is to experience colour.[x] Furthermore, some argue that Mary’s physical knowledge would allow her to recognise colours when she is first exposed to them; she would not need to be told what colours she was observing.[xi] Jackson argues, however, that physicalism is an “extremely optimistic view” of human brain power.[xii] I agree with Jackson on this point also. I use ultraviolet, which can be seen by frogs, fish, rodents and marsupials, to demonstrate the weaknesses of this physicalist argument.[xiii]

It is feasible that scientists could determine all physical facts about the perception of ultraviolet and that a human could learn these facts. Therefore, the physicalist must maintain that this person knows what it is to experience ultraviolet. To object to this thought experiment on the grounds that only certain species can see ultraviolet would completely undermine physicalism by admitting that there is some phenomenal experience frogs, fish, rodents and marsupials have that humans lack. This causes an explanatory gap between the physical facts and a visual conception of ultraviolet, which is too large for humans to bridge.

Some physicalists attempt to rebut the Knowledge Argument in a different way, most notably through the Ability Hypothesis. The greatest proponent of this theory, David Lewis, argues that new experiences allow one to gain abilities such as remembering, imagining and recognising, but they do not teach any propositional knowledge.[xiv] A simplification of this stance is: “It isn’t knowing-that. It’s knowing-how.”[xv] This implies a bifurcation in the meaning of “knowledge”—that knowledge and abilities are separate. However, I would argue this is a non-sequitur. When Mary leaves the monochrome room, she learns many things that would be categorised as “knowing-that.” For example, when looking at a rose, she knows that she is seeing red. It is only after this knowledge that she will “know-how” to identify other red objects. It is ultimately unsound to assume that abilities form without propositional knowledge. Thus, the physicalist argument is too weak to disprove the existence of phenomenal experience and non-physical knowledge.

Mary’s case shows that consciousness as defined by Searle does not capture the true complexity of human cognition. I believe a better conceptualisation of consciousness is proposed by Ned Block, who identifies the existence of phenomenal consciousness and access-consciousness.[xvi] Phenomenal consciousness entails the “experiential properties of a state” typically associated with the senses (sight, sound, smell, taste and touch).[xvii] Meanwhile, access-consciousness refers to any state that is necessary for reasoning or the rational control of action or speech.[xviii] A further distinction between the two is that a state is phenomenal consciousness in virtue of phenomenal content, whereas a state is access-consciousness in virtue of representational content.[xix] Relating back to Jackson’s thought experiment, it can be said that scientific information, like the physical facts Mary knows about colours, are representational content.[xx] Thus, in the monochrome room Mary is in an access-conscious state, but outside of the room she is in a phenomenally conscious state. Evidently, Mary’s experience shows that consciousness must be considered multifaceted, and Block’s model is a sound example of how consciousness could be studied.

Mary’s case illustrates the complexity of understanding consciousness. It has been shown by Jackson that qualia are an intrinsic property of phenomenal experience and, therefore, non-physical information exists. The implication of this on the nature of consciousness is that a non-physical consciousness must also exist. Block’s conceptualisation of access- and phenomenal consciousnesses ultimately provides an interesting model that considers the non-physical nature of the human experience.

Ruby Allen is currently completing a Bachelor of Politics, Philosophy and Economics with Honours. She is majoring in philosophy and intends to commence further study in this area once she completes her current degree. Her primary areas of interest include cognitive philosophy, the philosophy of language, and social and political philosophies, such as feminist and queer theories.


[i] John Searle, “On a Confusion About a Function of Consciousness,”  Behavioral and Brain Sciences, 13, no. 4 (1990): 635. https://doi:10.1017/S0140525X00080304. 

[ii] Frank Jackson, “Epiphenomenal Qualia,” The Philosophical Quarterly, 32, no. 127 (1982): 127–136. https://doi:10.2307/2960077.

[iii] Jackson, “Epiphenomenal Qualia,” 130.

[iv]David Lewis. “What Experience Teaches,” in Papers in Metaphysics and Epistemology, ed. David Lewis (Cambridge: Cambridge University Press, 1999), 262-290: 286.

[v] Ned Block, “On a Confusion About a Function of Consciousness,” Behavioral and Brain Sciences 18, no. 2 (1995): 227-287. https://doi:10.1017/S0140525X00038188.

[vi] Jackson, “Epiphenomenal Qualia.”

[vii] Martine Nida-Rümelin and Donnchadh O Conaill, “Qualia: The Knowledge Argument,” Stanford Encyclopedia of Philosophy, 23 September 2019,

[viii] Michael Tye, “Qualia,” Stanford Encyclopedia of Philosophy, 18 December 2018,

[ix] Tye, “Qualia.”

[x] Tye, “Qualia.”

[xi] Nida-Rümelin and O Conaill, “Qualia: The Knowledge Argument.”

[xii] Jackson, “Epiphenomenal Qualia.”

[xiii]Ellen J. Gerl and Molly R. Morris, “The Causes and Consequences of Color Vision,” Evo Edu Outreach, 1 (2008): 476, https://doi:10.1007/s12052-008-0088-x.

[xiv] Lewis, “What Experience Teaches,” 286.

[xv] Lewis, “What Experience Teaches,” 288.

[xvi] Block, “On a Confusion About a Function of Consciousness,” 227.

[xvii] Block, “On a Confusion About a Function of Consciousness,” 230.

[xviii] Block, “On a Confusion About a Function of Consciousness,” 231.

[xix] Block, “On a Confusion About a Function of Consciousness,” 231.

[xx] Roman Frigg and James Nguyen, “Scientific Representation,” Stanford Encyclopedia of Philosophy, 10 October 2016,


Block, Ned. “On a Confusion About a Function of Consciousness.” Behavioral and Brain Sciences 18, no. 2 (1995): 227-287. https://doi:10.1017/S0140525X00038188

Frigg, Roman and Nguyen, James. “Scientific Representation.” Stanford Encyclopedia of Philosophy. 10 October 2016.

Gerl, Ellen J. and Morris, Molly R. “The Causes and Consequences of Color Vision.” Evo Edu Outreach, 1 (2008): 476–486. https://doi:10.1007/s12052-008-0088-x.  

Jackson, Frank. “Epiphenomenal Qualia.” The Philosophical Quarterly, 32, no. 127 (1982): 127–136. https://doi:10.2307/2960077

Lewis, David. “What Experience Teaches,” in Papers in Metaphysics and Epistemology, edited by David Lewis, 262-290. Cambridge: Cambridge University Press, 1999. 

Nida-Rümelin, Martine and O Conaill, Donnchadh. “Qualia: The Knowledge Argument.” Stanford Encyclopedia of Philosophy. 23 September 2019.

Searle, John. “Consciousness, Explanatory Inversion, and Cognitive Science.” Behavioral and Brain Sciences, 13, no. 4 (1990): 585-642. https://doi:10.1017/S0140525X00080304.  

Tye, Michael. “Qualia.” Stanford Encyclopedia of Philosophy. 18 December 2018.

Featured image by Marcus Cramer via Unsplash


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