assume this is directed toward me, so I'll respond. We know that much of what Witt was saying was directed at Moore's propositions in his papers Proof of an External World and A Defense of Common Sense, so we're referring to specific propositions that Moore says he knows. Moore believes he has a justification for claiming to know "This is a hand (as he raises it to the audience)." Witt resists this notion, although he starts OC with, "If you do know [my emphasis] that here is one hand, we'll grant you all the rest (OC 1)." It seems clear to me that when Witt refers to hinge propositions or Moorean propositions he's saying that you don't know what you think you know, viz., Moore's use of the concept know doesn't apply because these statements don't fall within the domain of JTB. We don't normally justify these basic beliefs or Moorean statements. There are of course exceptions to this general rule (generally we don't justify them) and Witt points these out. — Sam26
I like to provide a brief defense of Moore's Proof of an External World. I don't claim Moore would agree of my defense, but let's just say I use Moore's position as a spring board to explore what I find as limitations to Wittgenstein approach to Ordinary Language. Let's begin where Moore ends his paper with the following:
“I can know things, which I cannot prove; and among things which I certainly did know, even if (as I think) I could not prove them, were the premisses of my two proofs. I should say, therefore, that those, if any, who are dissatisfied with these proofs merely on the ground that I did not know their premisses, have no good reason for their dissatisfaction."
Throughout the paper, Moore painstaking clarifies what it means by ideas such as "internal to our minds", “external to our minds’ and ‘to be met with in space”. After showing how all these ideas make coherent sense he goes on to provide the proof of "the existence of external things.” Moore thinks he has satisfied the conditions to be a rigorous proof. One of those condition being that a premiss which was something he knows to be the case and not something which only believe to be so. The premiss he cites is "I certainly did at the moment know that which I expressed by the combination of certain gestures with saying the words ‘There is one hand and here is another’. I knew that there was one hand in the place indicated by combining a certain gesture with my first utterance of ‘here’ and that there was another in the different place indicated by combining a certain gesture with my second utterance of ‘here’. How absurd it would be to suggest that I did not know it, but only believed it, and that perhaps it was not the case!”
Moore provides an excellent example where he demonstrates how this is a reasonable example of a proof. He gives the example of someone who is tasked in finding three misprints in a particular book. This individual could be incline to doubt whether three misprints are in the book, but the one giving the task could prove that there is by simply pointing to each one, 'There's one misprint here, another here, and another here.' Interestedly, Moore concludes, "Of course, A would not have proved, by doing this, that there were at least three misprints on the page in question, unless it was certain that there was a misprint in each of the places to which he pointed. But to say that he might prove it in this way, is to say that it might be certain that there was. And if such a thing as that could ever be certain, then assuredly it was certain just now that there was one hand in one of the two places I indicated and another in the other.”
It seems Moore is suggesting that he is not absolutely certain, in some philosophical sense, that "this is one hand and here is another" but nonetheless he knows this to be the case. Does this example need to fall in the domain of "Justified True Belief" to count as knowledge? I believe Moore is showing that we ought to revise this notion of what knowledge should be, what should count as knowledge. Philosophy sometimes can play a normative role, as well as a descriptive role.
Sure, Wittgenstein can look to see how the word "knowledge" functions in our forms of life. But sometimes concepts "evolve". I am sure the notion of "knowledge" has change from the Greeks, to the Medieval period, and to our Modern period. I would think if he explored the use of "to know" during these periods that they may be somewhat different. And did he not say in "The Blue and Brown Books",
"Philosophers very often talk about investigating, analyzing, the meaning of words. But let's not forget that a word hasn't got a meaning given to it, as it were, by a power independent of us, so that there could be a kind of scientific investigation into what the word really means. A word has the meaning someone has given to it."
Well, maybe we can view Moore as trying to "evolve" the notion of knowledge. But like all things competing for our attention, may lose out to more appealing notions.