Thursday, September 17, 2020

Another variant of the knowledge argument

We don’t have anybody like Mary who knows all of physics and yet has not yet seen color, and as Dennett has pointed out, it is hard to imagine what things look like from the point of view of someone who knows so much more than we do.

But here is a variant that may be easier for us to wrap our minds about: Imagine two people, one a completely colorblind early 21st century neuroscientist specializing in the visual system and the other a completely colorblind ordinary person. Suppose both receive color vision. If physicalism is true, the neuroscientist knows a lot more about what seeing red is like, even though (because we’re still in the early days of neuroscience) they don’t know that much about it overall. Thus, if physicalism is true, the neuroscientist would learn less by seeing red the first time, and should be less surprised. But would we really expect them to learn less and be less surprised than the ordinary person?

This variant is inspired by a remark I heard Brandon Rickabaugh give in a conference talk, that consciousness only seems more mysterious when one knows more neuroscience.


Martin Cooke said...


I would expect the neuroscientist to learn more, because she would now be able to make more sense of more known propositions. I cannot see why you think that she would learn less under physicalism. The ordinary person would not suddenly know all those more meaningful propositions. Indeed, she would probably have less interest in propositional knowledge than a scientist.

Also, I find your remarks about surprise to be unhelpful: it is easy to imagine a huge variety in the degree and even the nature of the surprise that different people will feel, to the same kind of thing happening to each of them.

Alexander R Pruss said...

I was thinking that if physicalism is true, the neuroscientist already knows a lot more about about what seeing red is like than the ordinary person does, so there is less to learn.

But your point is well taken. I should have distinguished from what is directly learned by seeing red and what is indirectly learned. And the neuroscientist learns more indirectly, since she can connect the new information with more facts. So, restrict my argument to what is directly learned.