Terrapin Station wrote:In a nutshell, I'm saying that what you're calling the Cartesian view (I don't actually agree that this is what Descartes was doing, but I don't want to get sidetracked into that discussion) is contextually incoherent, because the way that people arrive at that view is by assuming some realist data, either as a conceptual basis or as empirical support, but the view in question is that we can't know anything external (know by acquaintance).
Well, we might have to agree to differ, but that we can't know by acquaintance, in my view is Descartes' starting point. He only got round it by invoking the ontological argument. I'm not sure what "realist data" means. There is only data, it is the interpretation of that data which may be, and generally is, realist.
Anyway; how "people arrive at that view" doesn't make Descartes' approach contextually incoherent.
"Knowledge by acquaintance" is one of the three types of knowledge, the other two being propositional knowledge and how-to knowledge. I'm guessing that when you say "We can't know by acquaintance" you're saying that we can't know propositional knowledge by acquaintance (and more specifically, we can't know propositional knowledge that isn't the "same" as the specific knowledge by acquaintance in question).
In other words, in the vein of a similar discussion I'm having on one of the other philosophy boards, knowing a toaster by acquaintance simply means that there is phenomenal data of a toaster--in other words, a toaster appears. It's not a proposition about a toaster. We could say that knowledge by acquaintance fuels propositional knowledge that's the "same" as the knowledge by acquaintance--namely, "A toaster appeared," but yeah, it doesn't fuel a proposition such as "That toaster was purchased from Amazon."
What I mean by "realist data," and more specifically by assuming some, is that people assume things such as "I have an embodied mind, I have a brain, etc., and my body is situated in the world, where there's putatively a toaster that's not part of my body," as well as things like "we've studied brains and eyes and optic nerves and so on, and we know something about how they work." Those sorts of ideas lie behind idealist views--for example, the information about how eyes and optic nerves work is taken to support the idea that we can't directly experience things like toasters. The reason I'm saying this is incoherent is that it arrives at a conclusion by assuming things that can't be had if the conclusion is correct. This includes even the idea of a mind/not-mind distinction in the first place, which is the only way we can make sense out of a notion such as 'that toaster that appeared phenomenally is just a mental event."
Again, I'm not actually commenting on Descartes, because what I'm talking about isn't what Descartes was doing. He was focused on the idea of knowing (a la propositional knowledge) things with certainty, for the purpose of demonstrating how indeed we could know a number of things with certainty contra skeptical doubt. I'm not talking about anything like that.