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Why Mary Doesn’t Know All The Physical Facts


Daniel Sippel

London School of Economics and Political Science, GB
About Daniel
BSc Politics and Philosophy student (2012-2016). In 2015, he spends a year abroad at Sciences Po in Paris. His areas of interest are Epistemology, Political Theory and the intercept point of both. He hopes that he might one day be able to contribute to solve the issues with deliberative democracy.
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The famous Mary’s-room thought experiment by Frank Jackson features Mary, who knows all the physical facts but does not know what it is like to see red. I will argue, however, that it is impossible to know all the physical facts without knowing about qualia if we grant that qualia exist and are causally efficacious with respect to physical facts. As a result, physicalism cannot be refuted by Jackson’s famous Mary’s-room thought experiment, because it is flawed. To show this, I will firstly contextualise the question at stake and explicate the various notions and theories that are relevant to assess the question. Secondly, I will present Jackson’s thought experiment which features Mary, the brilliant scientist. After that, I will reject Jackson’s claim that qualia are causally inefficacious with respect to physical facts by using an example. With Goldman’s Theory of Knowing, I will demonstrate that since Mary is ignorant of causally efficacious qualia, she cannot construe an appropriate causal chain linking her belief of some physical facts to the fact itself. Therefore, she does not not some physical facts.

How to Cite: Sippel, D., 2014. Why Mary Doesn’t Know All The Physical Facts. Rerum Causae, 6(1), pp.25–36.
Published on 01 Jan 2014.
Peer Reviewed


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