Refuting Jackson’s Knowledge Argument (Mary version)
In 1982, Frank Jackson outlined an argument against Physicalism, now popularly known as
the Knowledge Argument. He aimed to prove that there existed epiphenomenal qualia which
could not be described in terms related to the physical world. I will be seeking to object to
this argument in this paper. Jackson’s argument can be summarised as follows -
Mary is a brilliant scientist specialising in the neurophysiology of vision who is forced to
view the world from a monochromatic room via a black and white TV monitor. She acquires
all the possible physical information about colours and how we perceive them, including all
the scientific facts about how the brain understands wave-length combinations which
stimulate the retina. So, what will happen when Mary is released from her room or is given a
colour television monitor? It seems obvious that she will learn something about the world and
our visual experience of it. But in such a case, as Jackson says, “But then it is unescapable
that her previous knowledge was incomplete. But she had all the physical information. Ergo
there is more to have than that, and Physicalism is false.”
This argument can be reconstructed in the standard Premise-Conclusion form as follows –
Premise 1: Mary has never seen any colours, but she has all the physical information about
colours.
Premise 2: When Mary sees a colour for the first time, she learns something about colours
and how we perceive the world.
Premise 3: If Mary knows all the physical information and facts about colours, but she still
learns something about them on seeing one for the first time; then colours have non-physical
properties.
Conclusion: Colours have non-physical properties.
Premise 4: If colours have non-physical properties, then physicalism is false.
Conclusion: Ergo, physicalism is false.
Premise 1 states that Mary, despite never having seen any colours, knows all the physical
information there is to know about colours. According to Premise 2, when Mary sees a colour
for the first time, she learns something. Premise 3 lays out that if Mary knows all the physical
information there is to know about colours but still learns something about them on seeing
them for the first time, then there is some information about colours which is non-physical.
From these three premises, we can derive a conclusion that colours have non-physical
properties. Premise 4 proposes a condition that if colours have non-physical properties, then
physicalism — the idea that everything that exists is nothing more than its physical properties
and that the only existing substance is physical — is false. From the previous conclusion and
Premise 4, we can derive that physicalism is false.
In Premise 2, we assume that Mary learns something new about colours on seeing them for
the first time. I would like to refute this by saying that instead, all Mary does is realise a fact
she already knows. She already knows all the relevant facts about say, the colour of the grass,
and how humans view it. So, all she does is see another representation of the fact like, “Oh,
the grass is green.” This form of phenomenal knowledge or concepts can only be learnt
through first-hand experiences, but they are physical properties of objects. The phenomenal
blueness of the sky is a phenomenal property of the sky. But Mary already knew the facts
which make this new knowledge true before her release, in another way. Another example of
this would be a man who knows that there is oxygen and carbon dioxide in the air that he is
breathing but might fail to recognise that there is O2 and CO2 in the atmosphere till it is
pointed out to him. Or simply, a woman who can feel pain, but would not realise her Parietal
Insular Cortical Neurons (PCINs) are firing unless it is explained to her.
Jackson might object to this argument by pointing out that Mary is supposed to know all
possible physical information and facts about colours and human vision before she leaves the
room. So, if she doesn’t, this means that whatever new knowledge she gains cannot be
knowledge of physical properties.
I would like to reply to this by explaining that no amount of information about physical or
even non-physical properties could explain to Mary what seeing a colour is like. However,
this does not mean that her knowledge is incomplete. Even if she knows all the physical
properties of a colour, there is a possibility of her being unable to understand physical
properties like colours before experiencing them for herself. I would argue that while Mary
might have all the necessary knowledge of physical properties, to be able to understand the
phenomenal properties among them would require her to experience them. Simply reading
records of physical facts of being in pain, and how the brain processes it, would not let a
doctor understand it himself without experiencing it. But this does not mean that the doctor
did not know all possible facts about pain beforehand under another description or realisation.
I would like to conclude by suggesting that Jackson’s Knowledge Argument does not
disprove physicalism, but instead it simply helps physicalists realise that there exist
phenomenal physical properties which need experience for their understanding, when realised
as phenomenal concepts such as colour even if we understand them in another way
beforehand.
