To keep yourself from sliding down the slope into solipsism, you need to come up with an explanation as to how we can know about the world even though "we don't see the world as it is". — Harry Hindu

Since you are asking "how we can know about the world even though "we don't see the world as it is", I will assume you could not keep yourself from sliding, and so you believe solipsism is the case unless demonstrated otherwise.

Ok, if that is your belief, I think we need to get some things straight before we can converse about this topic.

1. Please do not address me as if I exist independent of your mind. According to you I am only an aspect of your mind/consciousness. As such, think of me as another voice in your head. Some psychiatrists would call this auditory hallucinations, but they do not know what they are talking about because they probably are unable to grasp these fundamental rigorous logical arguments about reality.

2. Please do not flirt with indirect realism and say the cause of me exists outside your mind/consciousness because then you are admitting there could be something more than just your mind/consciousness. Remember, I am part of your mind/consciousness.

3. Do listen to what anybody who says you might have a dissociative identity disorder or multiple personality disorder. Those folk don't understand the logical implications that we need to accept when Solipsism is the case. Remember, those folk are just parts of your mind/consciousness as well.

4. To think of it, what if I convinced you that I exist apart from your mind/consciousness, This sounds like I am a contradiction, both existing independent of your mind and dependent on your mind at the same time. And we know contradictions can't exist therefore I only exist as part of your mind. That said, I think I also proved that any argument that would convince you of the opposite could also not be formulated. So, you cannot be convinced to give up solipsism with logic either.

Yours truly, you.

and other people are part of the shadows one experiences. Other people's existence is questioned by questioning the idea that you see the world as it is. Once you start to question your experiences, you question everything's existence - including words and the people that use them. Solipsism logically follows from unfettered skepticism about the reality of an external world. — Harry Hindu

Metaphysical theories like this are hopeless, no evidence can be presented to cure this mental disease, and only demands some sort of persuasion to cure it. I find a good dose of humor can do the trick to expose the absurdity of such a position.

“As against solipsism it is to be said, in the first place, that it is psychologically impossible to believe, and is rejected in fact even by those who mean to accept it. I once received a letter from an eminent logician, Mrs. Christine Ladd-Franklin, saying that she was a solipsist, and was surprised that there were no others. Coming from a logician and a solipsist, her surprise surprised me.”

Bertrand Russell

But what about Hoffman and Nagel's speech and written words? Are they something, nothing, or somethings?

Why do philosophers on this forum tend to put language up on this pedestal as if it is somehow separate from the shared world we live in - as if we access language differently than we do the rest of the world. We don't. Any skepticism of how we experience the world would be logically applied to the way we hear and see words because we access words the same way we access everything else - via our senses. If we question what words mean, we question what words are, or even if they exist the same way apples on tables do. — Harry Hindu

The Cartesian theater and Plato's cave are very dark places, but if the occupants still have their sanity and astuteness, they may notice light emanating from an entrance. So, when they boldly choose to exit, they will not find absolute certainty or those majestic eternal forms, but discover a chaotic, treacherous world that brave and ingenious people strive to cope and overcome by sharing their experiences, thoughts, and creations through the vehicle of language.

It would be nice if science worked that way, but it can't get around the fact we all exist in private worlds and other minds are essentially black boxes. I understand what you mean when you describe a sunset and how it makes you feel, but I'm also making a lot of assumptions to derive meaning from what you say: you exist independent of me; you exist independent of me and you're not a p-zombie; you're not a p-zombie and your "red" is the same as my "red", etc. None of these assumptions can be empirically justified. Science has nothing to say about whether solipsism is false. — RogueAI

Private world, an interesting idea, a devise to have a conversation about something that is imagine but like a work of fiction, neither true or false. But for the sake of further discussion, let us give it a little more precision. Because most us react and judge the world most of the time in a similar fashion, we can generally say we experience the world in a similar fashion. But this harmonization has another benefit, we can start to recognize when some of us do not experience the world like most. For example, we can start to recognize when someone is red/green color blind by administering the proper tests. But this is a standard test recognize by a community, not a private testimony by an individual on what the privately experience, that determines whether someone is red/green colorblind.

That said, I am not sure what sense I can make of saying “my experience of red is different than your experience of red” if we don’t appeal to some “outer” criteria.

I think the point is that, even if we can't understand or express what the taste of mint is, we know we taste it. We know we have various, and various kinds of, subjective experiences. — Patterner

Well, I know you taste food if you put it in your month and you say “that was good not too spicy” or I know when you don’t taste your food if you say “I got a bad head cold and I can’t taste anything. And I presume when you say “subjective experience” this may be demonstrated by saying this food you gave me is too spicy while I may feel it is rather mild.

Knowledge is a social phenomenon which is conveyed by language about a share world. A private language used to describe a private world is not a language at all. It is as if we came across a solitary being making occasional sounds and claiming it is a language used to describe the environment. That would be quite a stretch.

And that is the point Wolfram is trying to make against Hoffman’s idea that one can start with conscious as fundamental. Science starts with observers sharing similar reactions and judgments to a public world. Not an unknown private world of a conscious being.

On "The Concept of the Ruliad", Stephen Wolfram's idea of the "entangled limit of everything that is computationally possible: the result of the following all possible computation rules in all possible ways." Stephen characterizes this idea as "something very universal", "a kind of ultimate limit of all abstraction and generalization", "All possible rules", "All possible steps" and "All possible conditions." He finds from such an idea one can derive the laws of physics. He goes on to claim that Ruliad explains why we have the perception that universe has these specific laws that it does. Well his answer is that "we are bounded observers, embedded within the Ruliad. But we don't fully see the Ruliad but only see in the lens of our particular methods of perception and analysis. Here he shares some similarity with Hoffman's views.

This is my first time reading of such a theory but I have to say that I am a bit suspicious of its lofty claims. I think I can summarize around two points:

1. I can imagine him sitting a front of a computer and being overcome by an analogy, as Paley did when being entranced of the inner workings of a watch. Wow, by simply programming steps on a computer, I can simulate an object on a screen to move at a rate across a screen like an object in the real world. Therefore, all laws of physics must be founded on computational principles. Where is Hume when you need him?

2. Stephen, I presume, he is also a "bounded observer who has his own particular method of perception and analysis." If that is the case, does not this idea come from his particular method of perception and analysis? Or, does he have some Platonic insight into of realm of perfect ideas he only sees? I am reminded what Wittgenstein said in Philosophical Investigations, "47. But what are the simple constituent parts of which reality is composed? What are the simple constituent parts of a chair? The bits of wood of which it is made? Or the molecules, or the atoms? "Simple" means: not composite. And here the point is: in what sense 'composite'? It makes no sense at all to speak absolutely of the simple parts of a chair."

[reply="tim wood;985774"

Yep, it is a great discussion. But confusion begets confusion. Notice how Wolfram says to Hoffman you are an N of 1, as if this is reasonable concept to apply to a thing called “consciousness”. But, in comes The Private Language Argument, how could we make sense of “one-hood”, “thing-hood”, “truth-hood” ascribe to something private like consciousness? The underlying assumption Hoffman is convinced he knows is that he has consciousness, but this “knowledge” is occurring in the box, we have no idea if he applies such a concept “correctly”, nor do we even understand what it means to apply such a concept “correctly”.

David Hoffman meets Stephen Wolfram. A long video. Consciouness and a TOE. Fascinating - Wolfram cross-examines Hoffman - in a friendly but challenging wa — tim wood

Wittgenstein’s beetle in the box rears its ugly head again. Not sure if Wolfram knows it but he presents this argument from a philosophy of science meets philosophy of language angle.

We talk like we know what we refer to when Nagel talks about “what it is like to be a bat” or when Hoffman talks about “the taste of mint”, but it could be nothing, something, or somethings, all of which are irrelevant to the meaning of our expressions.

I don't think earlier Wittgenstein would exactly go along with this line of thought. Consider these sections from Tractatus,

“3.02. The thought contains the possibility of the state of affairs which it thinks. What is thinkable is also possible.

3.03 We cannot think anything unlogical, for otherwise we should have to think unlogically.

3.032 It used to be said that God could create everything, except what was contrary to the laws of logic. The truth is, we could not say of an “unlogical” world how it would look.”

And

“2.014. Objects contain the possibility of all states of affairs.”

2.0141 The possibility of its occurrence in atomic facts is the form of the object.”

And

“2.201 The picture depicts reality by representing a possibility of the existence and non-existence of atomic facts.

2.202. The picture represents a possible state of affairs in logical space.”

I think I proposed 2+2=4 as a sort of necessary truth. A whole lot of stuff falls apart if that isn't accepted. — noAxioms

Wow, that sounds pretty serious, if 2+2=4 is not a necessary truth a whole lot if stuff falls apart. What exactly do you have it mind? Maybe, for example, I am a kid at school learning arithmetic and I learn that addition and say to myself, “that is nice, it is true today but maybe tomorrow it will be false”, or that is nice but maybe the teacher is mistaken and it is really false”, and the kid decides to give up learning addition. Maybe if they were taught it was a necessary truth this unfortunate situation might not occur.

Just exploring this idea of “tense” and “affecting” logical form.

I will stop my inquiry into this since this may take the conversation in a direction the post may not have intended.

Sorry, the "that" was ambiguous. Better to have said, "A logical impossibility is so by virtue of its form. And we know that logical form is unaffected by tense." — J

And you know this I presume a priori.

A logical impossibility is so by virtue of its form. That form is unaffected by tense — J

That form is unaffected by tense is impossible because “by virtue of form?” If so, does that really say anything at all?

Fascinating stuff

There are two possible worlds that are accessible from today. In one, the sea battle occurs. In the other, it doesn't.

In no possible world does the sea battle both occur and not occur.

So in no possible world is the law of excluded middle contravened.

Possible world semantics provides a formalisation of such questions that allows is to avoid the sorts of issues Aristotle and Quine feared. Logic moves on. — Banno

It would be nice to see a post on the tension between temporal possible world semantics and scientific determinism. Or maybe there was?

Words can only be general because they denote universals. But universals are not things that exist. They are not objects as such. Designating them as 'things' is precisely the reification that you and Austin are complaining about. But because of Austin's presumptive naturalism, he will say that only things can exist.

Note again from Russell:

the relation 'north of' does not seem to exist in the same sense in which Edinburgh and London exist. If we ask 'Where and when does this relation exist?' the answer must be 'Nowhere and nowhen'. There is no place or time where we can find the relation 'north of'. ....it seems plain that the relation subsists

Universals are real, not as existing objects among objects, but as the indispensable constituents of the rational structure of reality - the 'ligatures of reason' - grasped by the mind, and necessary for intelligibility, yet not themselves located in space and time. — Wayfarer

So, there are things that exist and things that do not exist. If those things do not exist, it might subsists. If it subsists, it is real. If it does not subsists, it is not real.

The question I have, if it does not exist and does not subsists, and thus not real, what is it? Can you provide an example of something not existing or subsisting?

It reminds me of what Quine said in "On what there is", "Wyman's overpopulated universe is in many ways unlovely. It offends the aesthetic sense of us who have a taste for desert landscapes, but this is not the worst of it. Wyman's slum of possibles is a breeding ground for disorderly elements. Take, for instance, the possible fat man in the doorway; and, again the possible bald man in that door way. Are they the same possible man, or two possible men. How do we decide? How many possible men are there in that doorway? Are there more possible thin ones than fat ones? How many of them are alike? Or would their being alike make them one? Are no two possible things alike? Is this the same as saying that it is impossible for two things to be alike? Or, finally, is the concept of identity simply inapplicable to unactualized possibles? But what sense can be found in talking of entities which cannot meaningfully be said to be identical with themselves and distinct from one another?"

I believe that one has to take seriously his discussion in the whole section. — boundless

Indeed, and one should take seriously the point of the whole book. That is to distinguish between what has sense and what is nonsense, what can be said and what is shown. To draw the limits of language and remain silent, to say nothing except what can be said.

“6.53 The correct method in philosophy would really be the following: to say nothing except what can be said, i.e. propositions of natural science—i.e. something that has nothing to do with philosophy—and then, whenever someone else wanted to say something metaphysical, to demonstrate to him that he had failed to give a meaning to certain signs in his propositions. Although it would not be satisfying to the other person—he would not have the feeling that we were teaching him philosophy—this method would be the only strictly correct”

So solipsist asserting “they alone exist in the world” or any other such permutation, asserts nothing all at.

As for later Wittgenstein, while his approach differs from his earlier work, would be equally dubious of the solipsists assertions, This was done by showing how the solipsist abuses our ordinary use of language.

Ironically, Wittgenstein's Tractatus can also be invoked to support the view that one can't go outside one's perspective (see TLP 5.6-5.641...here a link). And in fact, one can cite the later Wittgenstein's view that sense can be pragmatic in nature. Even if my picture is wrong, then, if it still has pragmatic use, I don't see why it would be 'nonsense'. — boundless

I think these sections are serving the purpose of putting the implications of Wittgenstein view of language and how we make sense of the world, deciding on what can be said and what can be shown. In these sections, solipsism is not something that can be said, but only shown.

5.64 Here it can be seen that solipsism, when its implications are followed out strictly, coincides with pure realism. The self of solipsism shrinks to a point without extension, and there remains the reality co-ordinated with it.

In H.O Mounce’s Wittgenstein’s Tractatus An Introduction, puts it nicely when he says, “For the solipsist in wishing to deny the independent reality of the world, in maintaining that only he and his ideas are real, has the idea of his self as an object standing, as it were, over and against an unreal world. But when he realizes the confusion in this, when he sees that there can be no such object as he takes his self to be, the world reappears as the only reality in which his self can manifest itself.”

To add a quote of a much forgotten book, Mill’s On Liberty, he analyzes in Chapter II Of the Liberty of Thought and Discussion, “We can never be sure that the opinion we are endeavoring to stifle is a false opinion; and if we were sure, stifling it would be an evil still.”

Quite an ideal to live up to!

I think it is quite clear that those who suggest censorship, de-platforming, the heckler’s veto, cancel culture, etc. are of the intolerant variety, and the tolerant ought not to tolerate their behaviors. — NOS4A2

I think the beauty of a society that has this freedom is the transparency it can offer. You know where your fellow citizen stands and they know where you stand. The risk I see is any attempt to eliminating the voice might send it into hiding, and this poises many dangers to society. So, if both parties are attempting to shut out each other’s voices, what is left? A society uncertain where folk stand or think, paralyze in fear, developing some sort of paranoid suspicion.

So let them have their voice, so at least you know who you have to stand up to.

So what.
the punishment is proportional
— Richard B
An eternal punishment for a transient sin is proportional? Not seeing it. — Banno

I know for a non-believer, yep.

But for a believer, there is a rule given by the creator, and the creator decrees there is one eternal sin that cannot be forgiven.

This is accepted or not. Sort of like accepting Euclid’s axioms and seeing what follows. For example, “A point is that of which there is no part.” What hell is that? O.k. I will accept it and see where this goes.

One commits an eternal sin according to God not a transient sin according to Lewis.

I would characterise the thread quite differently. You can read Lewis' argument and comment on it. The punishment of the damned is infinitely disproportionate to their crimes. — Banno

Well according to the Bible :

Mark 3:28: "Truly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they utter".
Mark 3:29: "But whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin".

These are the rules of the game for the believer. The believer recognizes the book as authority for their religious life. This sin stated as an “eternal” sin, not a “finite” sin. Thus, the punishment is proportional.

A problem here, I believe, is that you are assuming that there must be some kind of correspondence of our mental constructs of the world and the world in itself. The structure of the model must somehow reflect the structure of the world. But how can we verify this assumption? — boundless

I think Wittgenstein’s Tractatus may offer a solution here. That is in order for us to make sense of the world, that is to avoid speaking non sense, our language, mental construct, and the world must be isomorphic. This is not an outcome of empirical verification but of logical analysis.

God should have hired David as his publicist, since he did such a better job of articulating the process of eternal damnation than the Bible, maybe there would have been less sin in the world. At a minimum, Lewis may have demonstrated the concept of God as a “omnipotent influencer” is not a necessary property.

This is quite counter-intuitive. But imagine it is but it is true theory. This prevents us from substantivizing information and treating it as an entity that passes from one side to the other. Which has many consequences for information theory like the ilusion of transmission. — JuanZu

Quite a claim, that there is an illusion of transmission when we substantivizing information.

If a l wrote a letter to my friend providing information on directions to my house. I can say I have transmitted this information by means of a letter. What was transmitted to him if he arrived at my house? The incorporeal information or material letter? Sending just the paper does not ensure the visit but the information in the letter.

My love for my county was transmitted thru generations by my sacrifices on the battlefield. Do I need a theory to tell me that love cannot be transmitted thru history even though love may not be a substance? Your theory may be true but at the expense of limiting our use of language.

he idea does bug me, the thought that if it's all just chemicals then there would be no real reason to not plug into it. What difference is there if we can just replicate everything? — Darkneos

Interesting criteria for choice, “it’s all just chemicals”. Well putting aside what goes on in your brain for a moment, are those “real objects” in front of you just chemicals as well? Or those “chemicals” got some special ontological status for you? And those “chemicals” in the brain, I guess just, are just chemicals of what? Something unknown?

So I guess you are worried about the causes of the “chemicals” in your brain. You seem to want those causes to be “outside” your brain. But the causes of an experience machine are outside your brain.

Maybe reading Sartre might help when it comes to making a choice in life. But maybe not, thats a choice as well.

Thus, the existence of humans is designed — A Christian Philosophy

Yep, this seems to be making a come back. When we all thought Hume buried the design argument, philosophers are starting to defend it again, see Chalmers, Reality+: virtual worlds and problems of philosophy. Since virtual reality is simulated to resemble our reality maybe we are just simulation ourselves. But now this demands a simulator. While this concept does not resemble the Christian concept of God, it opens the door yet again.

Yep, especially if notions of time and space come into existence and have sense emerging from the big bang. Thus, asking questions of “cause” may have little sense. But our imaginations do not want to be bound by any thing physical, thus we our doomed to ask disguised questions that seem intelligible but are really are distress calls for new conceptions.

quantum mechanics which considers physical quantities at the atomic level as merely random results of measurements — Ypan1944

I think even Einstein would say quantum mechanics is not fundamental given his famous quote, “God does not play dice.” Heisenberg may have even question what sense to call quantum mechanics fundamental when he said “What we observe is not nature itself, but nature exposed to our method of questioning.”

Lets explore this idea:

You express the following thought to me, “A circle has four sides.” I may reply, “Not sure what you are thinking here, but a square has four sides.” Is this not doubting what thoughts you may have about “circles.”? You might want to say, “Well privately, I know what I am referring to or thinking about.” Sure, you have thoughts that no one understands, but how could we agree that they are thoughts at all!?

Not everyone agrees with Wittgenstein. If you don't know what red means, how could you use the word "red"? If you are a colour blind, how could you tell red objects? For you being able to use the word red means that you know what you mean by red from your experience of seeing red via your perception, and folks describing red objects as red. — Corvus

Quine, in Word and Object, addresses how folk who are color blind use the word correctly.

“Uniformity comes where it matters socially; hence rather in point of intersubjectively conspicuous circumstances of utterances than in point of privately conspicuous ones. For an extreme illustration of the point, consider two men one of whom has normal color vision and the other of whom is color-blind as between red and green. Society has trained both men by the method noted earlier: rewarding the utterance of ‘red’ when the speaker is seen fixating something red, and penalizing it in the contrary case. Moreover the gross socially observable results are about alike: both men are pretty good about attributing ‘red’ to just the red things. But the private mechanisms by which the two men achieve these similar results are very different. The one man has learned ‘red’ in associate with the regulation photochemical effect. The other man has learned ‘red’ by light in various wavelengths (red and green) in company with elaborate special combination of supplementary conditions of intensity, saturation, shape, and setting, calculated e.g. to admit fire and sunsets and exclude grass;…”

But we do know who the question refers to... Socrates. Yes, there is more that one can learn about Socrates, but that is still about Socrates. Kripke's point, that we do not need a definite description at hand in order for a propper name to function correctly, stand... no? — Banno

“But we do know who the question refers to…God. Yes, there more that one can learn about God, but that is still about God. Kripke’s point, that we do not need a definite description at hand in order for a proper name to function correctly,…no?”

Hmmm, I suppose neither a logical construction that Anselm puts forward.

The nature of living systems is to change themselves in ways that retain a normative continuity in the face of changing circumstances. Cognition is an elaboration of such organismic dynamics. A.I. changes itself according to principles that we program into it, in relation to norms that belong to us. Thus, A.I. is an appendage of our own self-organizing ecology. It will only think when it becomes a self-organizing system which can produce and change its own norms. No machine can do that, since the very nature of being a machine is to — Joshs

Nice passage. Stuck this in Chat Smith to see if it confirms the veracity. And, there was no disagreement. But I guess this is expected based on what is expressed.

Yep. As your asking me that very question implies that you understood my post and what to do about it. Doubt sits in a background of certainty. That's a step beyond the insincere affectation, into the nature of discourse. — Banno

Reaction to this post:

Sometimes in philosophy we show by arranging our concepts into a persuasive paradigms. This is very different than presenting logical arguments from true premises to demonstrated conclusions. Like “cause and effect”, we accept these concepts and enjoy the fruits, not born from logical demonstration but life forces these concepts on us. Accepting the sandwich, our big bang to certainty.

I think that's a wonderful definition even though I have no idea what it means. Sounds all philosophical and stuff. — T Clark

Quine could generalize the general.

Yes, a true sentence is about what is the case. But note that truth is a property of the sentence, not a property of the rain — Michael

If I said “It is the case that it is raining outside”, I do not mention anything about “truth” Would we need to say “what is the case” is a property of “It is raining outside.”? Or just say “what is the case” is neither a property of a sentence nor the rain? Like those who assert “existence” is not a predicate.

“As against solipsism it is to be said, in the first place, that it is psychologically impossible to believe, and is rejected in fact even by those who mean to accept it. I once received a letter from an eminent logician, Mrs. Christine Ladd-Franklin, saying that she was a solipsist, and was surprised that there were no others. Coming from a logician and a solipsist, her surprise surprised me.”

Bertrand Russell, Human Knowledge: Its Scope and Limits

In summary, the idea of solipsism should not be taken seriously and should be rejected on different soil.

There is a difference between knowing the key is on the desk and being certain that the key is on the desk.

That's kinda the topic of On Certainty.

The justification for a claim to knowledge is the answer to "How do you know?" It will not do here to simple repeat your claim - I know the key is on the table because the key is on the table; I know this is a hand because it is a hand.

This is what is being said in the first few pages of On Certainty. Moore is unjustified in claiming that he knows this is a hand. Yet, it is true that this is a hand; and he is certain that this is a hand. The remainder of the book is an exploration of this oddity. — Banno

Nicely put. How about I know this is a hand because I am pointing to it, we both see it, and we both understand what I am talking about.

You’re making Wittgenstein’s point for him. He sees Moore’s raising of his hand as a performance which is grounded in a picture of the world which cannot be proved more correct than any other. To doubt the truth of this picture is to substitute a different picture, a different language game, just as doubting the picture of the world implied by the rules of chess is to no longer be playing chess. Moore’s demonstration convinces doubters of its certainty by bringing them to look at the world in a different way, not by satisfying them of its correctness. — Joshs

If Moore knows, that would mean there's a sense of "know" that amounts to being unable to doubt. And per Hume, you can't prove what you can't doubt. So Moore would have some kind of unprovable knowledge, which doesn't sound right. — frank

Moore's paper, "Proof of an External World”, is an appeal to common sense. His intuition tells him that a philosophical analysis arriving at a radically skeptical answer is not a source of truth but evidence that something has gone wrong. I believe Wittgenstein would hold the same position as Moore when he says, “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!” However, Wittgenstein seems to think Moore is in error here in a different way. I believe Norman Malcolm summaries this position nicely when he says:

"But, this insight led Moore into an error. (This is the second layer of meaning.). His perception of the absurdity of saying , in that situation, "I don't know if I have clothes on (or have hands)" drew him into the assumption that it would be correct to say "I know I have clothes on." Yet what Moore had actually perceived was that nothing in that situation made a doubt as to whether he had cloths on intelligible. He should have concluded that both "I don't know" and "I know" were out of place in that context. "I know" is often used to express the absence of doubt. But the absence of doubt and the unintelligibility of doubt are very different things. Wittgenstein says in the Investigations, "I know...may mean "I do not doubt...but does not mean that the words "I doubt...are senseless, that doubt is logically excluded." Wittgenstein is referring here to the way that "I know..." is used in ordinary language. He is saying, correctly, that this expression is not used in ordinary language to make a conceptual, philosophical point. But this is kind of point that Moore needed to make, namely, the point that the statement "It is uncertain that I have clothes on" would be a conceptual absurdity in that situation. I suspect that Moore was misled here by the assumption of Excluded Middle: "Either I know it or I don't know it." He perceived that "I don't know it" couldn't be said, and wrongly concluded that "I know it" must therefore by right and true." (Moore and Wittgenstein on the Sense of "I know")

Some remarks on this summary

I find it strange to not say "I know here is one hand" in the particular context. Would it also be absurd for Moore to say in front of such an audience of skeptical philosophers that "I know it is raining outside" while looking outside the window while it is raining. Malcom says, "Being perfectly certain (i.e. objectively certain) of something in the sense of regarding it as unintelligible that one might be wrong-is an attitude, a stance, that we take towards various matters: but this attitude does not necessarily carry truth in its wake. (Nothing is Hidden)". But in these contexts, are they not carrying "truth in its wake." How is what Moore is doing, by holding up a hand and pointing to it and saying "Here is one hand" making a conceptual point only? Is this not a way of establishing the truth, or the correctness of what he is saying? Moore is not trying to describe the language game "I know", he trying to get the language game of "I know" right. He is responding to the skeptical philosopher that has taken the language game of "I know" and distorting it in such a way that knowledge becomes a logical impossibility. For Moore, in the example he provides, "knowing that" merges with "knowing how". Moore is aware of the truth, understands the fact that he has two hands by demonstrating that he can point to one hand and saying "Here is a hand." Why can't there be other ways of clearing up philosophical confusion other than describing how words are ordinarily use. For example, why not tidy up the concept itself, narrow its scope, broaden its scope, eliminate its absurdities, etc.