We can’t have empirical evidence that rules out 4. — Michael

I disagree. When one demonstrates that BIV is physically impossible, scenarios 3 or 4 were never a logical possibility. What was conceptualize from actual functional brains was demonstrated to be false.

Just because one can say or imagine something does not make it possible.

But as a fictitious narrative, one does not need to worry about the support of empirical evidence.

If a neuroscientist gave you evidence that a brain could not be stimulated in such a way so as to produce simulated percepts, would you be convinced that the brain in a vat hypothesis is impossible? — NotAristotle

Many are willing to accept the scientific evidence of what the brain does to kick start the thought experiment that we could be BIVs. But as soon as you discuss the possibility of introducing scientific evidence to show that a BIV is not possible, it suddenly is “begging the question”, or that evidence was somehow fabricated in the scientist’s mind.

I would agree that the act of saying "ouch" names a behaviour, but I would not agree that the word "ouch" names a behaviour. — Luke

I agree that the word "ouch" has to be in context. It could be the Organisation for the Understanding of Cluster Headache, a BBC website reflecting the lives and experiences of disabled people, a term in the dictionary or a speech act from someone having a rock dropped on their foot. As Wittgenstein said "The question is: "In what sort of context does it occur?" — RussellA

I think Norman Malcolm in "Turning to Stone" helps clarify what is being discuss here. He says:

"Wittgenstein's argument has established that there is an essential connection between the meaning of first-person psychological language and the primitive expression of fear, anger, pain, in human behavior. But how does this connection make its appearance in the teaching of language? Wittgenstein puts the question like this: 'How does a human being learn the meaning of the names of sensations?-of the word "pain" for example"(PI 244). In a familiar passage he suggests what seems to be the only possibility:

Words are connected with the primitive, the natural, expression of the sensation and put I'm their place. A child has hurt himself and cries; and now the grown-ups talk to him and teach him exclamations and, later, sentences. They teach the child new pain-behavior.
'So you are saying that the word "pain" really means crying?' On the contrary, the verbal expression of pain replaces crying and does not describe it (PI 244)

The suggestion does not mean that adults get the child to identify sensation of his as pain. This would only reintroduce the untenable notion of 'inner ostensive definition'. Nor does the suggestion mean that the word 'pain' stands for or refers to crying-which would be a form of behaviorism. What the suggestion says is that the adults coax the child into replacing his crying with words such as 'hurts' or 'pain'. The crying was a primitive expression of pain. The uttered words, by taking the place of the primitive expression, become an expression of pain. Uttering those words becomes, for the child, a new form of pain-behavior; and for others it serves as a criterion for the child's being in pain."

But of course if we are brains in a vat then it may be that “real” physics isn’t exactly like the fabricated physics that we are being programmed to experience, and so one cannot really use physics to disprove the physical possibility of brains in a vat without begging the question. — Michael

Is the unseen scientist fabricating you to think that this is plausible, or the unseen scientist fabricating me to say it is not plausible to fabricating these thoughts? But this sounds strange, are you saying that we are not free agents making rational arguments for or against this idea of the BIV? Sounds like we are mere tape recorders for some unseen entity. This entity can fabricate physics and fabricate logic, I guess what follows would be that it would difficult to have a conversation with such an entity. Damn, never mind, that was fabricated too.

To use the world we experience as empirical evidence that brains in a vat are physically impossible is to beg the question and assume that we are not brains in a vat. — Michael

Nicely put, but I would have to disagree here. If a physicist says it is physically impossible for something to travel faster than the speed of light, are they begging the question? In this scenario, the scientist is not assuming we are not brains in a vat, they would be empirically demonstrating that the idea of a brain in a vat cannot function the way a brain in human does with its natural environment.

It is the philosopher bringing in its own metaphysical baggage that gets them all tied up in a knot. The scientist is trying say something of this world, the philosopher is pretending to, but in the end they are just creating fairy tales.

think it may even be physically possible. It is in principle much like a Boltzmann brain, and physicists seem to accept that they are physically possible.

But of course if we are brains in a vat then it may be that “real” physics isn’t exactly like the fabricated physics that we are being programmed to experience, and so one cannot really use physics to disprove the physical possibility of brains in a vat without begging the question. — Michael

I will not address the Boltzmann brain (as there is another thread for that) but go with the current scientific theory that human brains are a product of millions of years of evolution. What if scientists biologically demonstrate that the BIV cannot function like a brain with a human body (the brain just degrades when artificially stimulated). However, as you put it, this does not refute the possibility that this experience of “scientists demonstrating the BIV cannot function” was not fabricated in some BIV. But why should we say logical possibility trumps physical impossibility? Ours ideas are derived from our experiences of physical brains. The manifestation of a functional brain is a human being who articulates what is possible and impossible against a background of an external world. How should we think of an idea that says, “it was fabricated in a BIV to think it was fabricated in a BIV.”? This idea has all the qualities of a fiction, not either true/false or possible/impossible. This is where this type of metaphysical reasoning fails, it starts out trying to say something about the world in which we live in, but quickly degrades into phantasm where it logically excluded any verification, falsification, confirmation gathered by our experiences.

I am reminded of a quote from David Hume from Dialogues Concerning Natural Religion; where he thoroughly criticizes the metaphysical design argument for the existence of God, “A total suspense of judgment is here our only reasonable resource.”

I do not believe BiV is possible. I believe semantic externalism doesn't prove that BiV is impossible; I think BiV is impossible for other reasons. — NotAristotle

And what are those reasons?

For Wittgenstein:
1) The word "ouch!" replaces a behaviour.
2) Naming means attaching the word "ouch!" to a behaviour, ie, the word "ouch!" names a behaviour.
3) Therefore, "attaching" a word to a behaviour means "replacing" a behaviour by a word. — RussellA

This is not what Wittgenstein is saying. “Ouch” is an expression of pain, not naming the behaviors that commonly associated with pain. If my arm is stabbed, I do not grab my arm and look at my face wincing in a mirror and say “that behavior is ‘Ouch’. Alternately, I may just say “Ouch” without any of the pain behaviors, or the behavior varies from event to event.

If BiV is phenomenally the same as not-BiV, then I don't see how semantic externalism can do any work. Even someone who is not-BiV would not know what they meant by real and not real. — NotAristotle

Given that if metaphysical realism is true then something like us living in the Matrix is possible, Putnam's argument is that metaphysical realism and semantic externalism are incompatible, and because he believes that semantic externalism is true he concludes that metaphysical realism is false. — Michael

To be the same principle the body would in some way need to be silenced, or asleep, or unconscious, as in the movie Matrix. Of course, in these states he wouldn't be seeing or hallucinating anything, but dreaming. If the rest of the body is included, awake, and in full working order it would notice that it is in a vat, that it cannot move, is suspended in some sort of liquid, and so on, and his words could directly refer to the environment. — NOS4A2

I am curious, do you all believe that a "BiV" is possible? If so, why do you believe it is possible? Just because you can imagine it?

Why would touching be considered impossible? Touching is by many considered an object coming into contact with another, which perhaps requires the objects occupying the same space. And occupying the same space is considered impossible by nearly everyone. — elucid

Let's try these examples of occupying the same space:

1. Consider Matryoshka dolls. This is a good example of each smaller doll occupying the same space of the prior larger doll.

2. Take a 1 cubic meter container and add an equal mixture of two inert gases and close it. Wait a moment and I have two gases occupying the same space in the container.

3. I draw a square object and overlap it with a circle object, then color in the space where they overlap. Conclusion: The colored space where the two shapes overlap occurs in the same space.

It seems occupying the same space is not impossible.

As opposed to how well philosophy doing right now at being relevant? Every time I go into a book store I check out the philosophy section and it invariably is tiny and has just a few copies of books by the same 4-6 authors. Philosophy has become so scared of error that it's afraid to be relevant. Sometimes I even think the arcane vocabulary becomes a hiding mechanism. — Count Timothy von Icarus

Thank Descartes for telling us it is all a dream but don't worry God would not want to fool us.

The Age of Enlightenment at its best.

Oh for sure. But when someone say's "does touch really exist," I assume they mean: "from the standpoint of fundemental physics or metaphysics," simply because the question is silly in any other context.

This is an example where the understanding wrought by the linguistic turn seems to backfire. "Take language the way it is commonly used," is all well and good advice in some cases, but it missteps when it assumes that people don't ever think about metaphysics in their day to day lives. This just doesn't seem to be the case. Books on this sort of thing wouldn't sell millions of copies and churches wouldn't be packed each weekend if these sorts of questions only interested a few egg heads. In our ordinary, everyday lives we still sometimes ask deep metaphysical questions of this sort. — Count Timothy von Icarus

Maybe, but then philosophy flirts with the risk of being viewed as irrelevant, a joke, a psychological disorder, a fictitious narrative, a new religion, etc.

Of course, just because we can't disprove an idea it does not make it true. It does not make it false either. It is an untestable idea. — Truth Seeker

This is what we call an imagination producing a fiction. For example, I can enjoy a novel of fiction where the author has a rich history of some made up land. But there is no proving that this fictional history is true or false.

It is possible that what I perceive is either a dream or a hallucination or an illusion or a simulation and not objectively real. — Truth Seeker

I would disagree with this assertion. In order for one to understand what is a dream, hallucination, illusion, or simulation, one must contrast this with what it is not. This is the world in which we interact with, talk about, act on, born into, communicate with others, learn from others; basically, the background in which we accept and act in. For example, one typically learns the concept of "dreaming" from their parent when upon waking up from sleeping they begin to report strange accounts that never happened with a subsequent reassuring from the parent that all was a dream.

am sure we do. I agree that because humans have similar biologies we judge colour the same, and I am sure that your subjective green is the same as my subjective green. I believe this, but I don't know it, as I cannot see into another person's mind — RussellA

Consider On Certainty(OC) 504, "Whether I know something depends on whether the evidence backs me up or contracts me. For to say one knows one has pain means nothing. "

The same goes for private sensations of color, for to say one knows one has the sensation of green means nothing.

Or, OC 548, "A child must learn the use of colour words before it can ask for the name of a colour." Again, the emphasis here is language use, not recognition of color sensations.

In today's terms, Wittgenstein's approach in PI is that of an Indirect Realist rather than a Direct Realist, whereby a name is a label for an object in the world than rather than a description of it. — RussellA

Consider OC 505, "It is always by favor of Nature that one knows something." Notice he is not saying it is by the favor of our awareness of private sensations that one knows something. This is evidence he would not support Indirect Realism.

I will leave this discussion with one more quote from Wittgenstein from "Culture and Value" which suggest the importance of what can and cannot be said, "Couldn't one actually say equally well that the essence of colour guarantees its existence? As opposed, say, to white elephants. Because all that really means is: I cannot explain what 'colour' is, what the word "colour" means, except with the help of a colour sample. So in this case there is no such thing as explaining 'what it would be like if colors were to exist'.

I agree. But to avoid any ambiguity, does the sentence mean i) what appears green to us science has discovered has a wavelength of 550nm or ii) science has discovered that a wavelength of 550nm is green independent of any observer ? — RussellA

What it means is human beings collectively will call the green standard sample "green", and current scientific technology will measure the light reflected off such a standard sample as 550 nm.

By the sentence "a device that detects colour", do you mean i) a device that is able to directly detect the colour green independent of any observer or ii) a device that is able to detect the wavelength 550nm, and has been programmed by a human that a wavelength of 550nm is named green ? — RussellA

What it means is a device that can detect light with a wavelength of 550 nm light, and humans collectively has established that light of such a wavelength is called "green", and the device can be programmed to report out the name of the color.

I am sure we do. I agree that because humans have similar biologies we judge colour the same, and I am sure that your subjective green is the same as my subjective green. I believe this, but I don't know it, as I cannot see into another person's mind — RussellA

I think this is where Wittgenstein would say this philosophical discussion is "going off the rails" so to speak. The language game is learned in a community from color language users that can judge color samples the same, and use the color names in the same way. This is how they know they see the same color of an object. This is all we have and it is all that matters when discussing color.

It then comes down to arguments for and against Indirect and Direct Realism. — RussellA

I would say Wittgenstein is not supporting either Indirect or Direct Realism since both are philosophical theories in which language goes on a holiday.

If green exists in the world independent of the mind, then what exactly has science discovered in such a world that relates 500nm to 550nm but not to 580nm ? — RussellA

1. The color of an object is determined by which wavelengths of light it reflects. For example, plants appear green because they contain the pigment chlorophyll. Chlorophyll absorbs all other wavelengths of light. Green is reflected so it is green light that hits our eyes. Science discovers that the green light has a wavelength of 550nm and not 580nm, and yellow light has a wavelength of 580 nm and 550 nm.

2. If you have no problems with a device that detects color by utilizing scientific theories of light and not positing the device having private color sensations, why not humans that have evolved biological apparatuses to do the same without private color sensations?

3. To get poetic, you seem to picture the color experience as if you are in a room with no doors or windows but just a TV set with a wire coming from the wall that you presume is sending signals from an outer-world that you can’t be so sure if it accurately reflects reality. I, on the other hand, have an open window with a clear view. If the is a metaphysical dispute, I like to be optimistic and believe we are seeing the same thing. And maybe that is the more reasonable position because we have similar biologies, judge color the same , use the same words, and inhabit the same world.

If philosophy was meant to be fun, it would be being promoted at the Edinburgh Fringe Festival. :smile: — RussellA

Well, we always have Monty Python if an ounce of levity is needed.

We have devices that can detect the wavelength of 550nm emitted by a variety of objects. The device doesn't know the name of the wavelength of 550nm prior to it being named green by a human. — RussellA

1. Scientists are not naming the color green "550 nm." Scientists are characterizing the color green with the property of 550 nm based on the latest scientific theories of light. This can only be done if there is general agreement by humans on what they judge to be green. This is done be utilizing standard samples that we all would agree are called "green."

2. The device will be calibrated to detect particular wavelengths of light from a standard object that human beings collectively judge to be green. This shows the device is working as intended. The device is not calibrated by the color that exists in someone's mind. We need the device to detect the color of an object that is independent of a human but will detect and report the color as humans do.

3. If I want to determine a particular color of a swatch, I may send it out to a company who has sensitive device that can provide a very nuance color determination. So I put it in an envelop and mail it in and in a few days get a report on its color. I am not sending a color that exists in my mind in the mail.

4. The human brain is like the device that detects color. It has evolved to sense and discriminate different wavelengths of colors. This is demonstrated by humans collectively judging and naming colors of particular objects. If a human being has a problem with judging color like the community, scientists may take an interest to understand what is happening in the brain. Maybe with this knowledge they may even attempt to help the human harmonize more.

5. If colors exist in the mind, why did scientist study light and color that is independent of the human? Because it exist independent of them. What scientists may want to study is how the brain reacts to color and light. What they do not study is what color the human is "actually' experiencing. And the reason for this is not technological limitations, but what is being expressed in language is incoherent.

What I want to show with this discussion is this philosophical theory that "color exists only in the mind" has no relevance to how humans use color language in the everyday life and in the pursuit of science. But as a story of entertaining fiction, I do get a good laugh.

As the colour of the wavelength 550nm can only be determined by the mind, the colour green can only exist in the mind. — RussellA

We have devices that detect colors on a variety objects that will agree with human judgement. These devices are not detecting color in the minds of humans but on objects. Additionally, if you use the device on the human brain you will be getting the color of the brain not what the brain is sensing.

This simply shows this view colors only existing in the mind is confused and unfruitful.

I like to suggest a different view on "What is Truth." Instead of appealing to Platonic Essences, psychologism, or analytical formulations, I like to take a roughly thought-out Naturalistic position. Truth is just a manifestation of the brain's interaction with its environment through language, to put it as general as I can. It is not a property of propositions, sentences, the world, the mind etc... The human brain has the ability to recognize stimuli "as true" because it has evolved over many eons the innate ability to condition itself to respond to environmental stimuli in ways that have proven valuable for the host. The brain recognizes its conditioning in particular ways, which in turn, we get a manifestation of this recognition in language by saying, "that's true." From this recognition, the host may act as it sees fit.

Let's look at the example, "1 + 1 = 2". All of us who have learned mathematics would say, yep this is a true statement. But not because we all have some strange ability to look into the Platonic realm of Ideas and see that it is true. But because we have conditioned ourselves to react to the symbols "as true". A child has no idea before learning mathematic what these symbols mean, but after proper conditioning, the recognition of it "as true" happens.

Could the brain mess-up, of course. Could the brain set-up conditionings that are not useful, of course. And that is what we exactly see in humanity.

The expression "Truth" may be as primitive as the expression "Ouch".

I disagree that Wittgenstein would agree that words, such as, right, accurate, judgment, etc lose their sense, if that's what you're indeed saying. — Sam26

They lose their sense in terms of talking about private sensations like they are public objects. For example, “I correctly recognize my past sensation is the same one as my current sensation” vs “I correctly recognize the person in the picture is my neighbor.”

another.

Wittgenstein's Beetle in the Box is an argument against Direct Realism. — RussellA

The Beetle in the Box is not to put forward a philosophical theory or to show support for indirect realism theory but to show that the model of “object and designation” is irrelevant to the meaning of the terms expressed in the language game of pain.

In fact he does not even support indirect realism, consider PI 304, “The conclusion was only that nothing would serve just as well as a something about which nothing could be said.”

An indirect realist would not say this. They would say that there are “somethings” and these somethings are private sensations and we have much to say.

Again, recognising the private sensation will help one to use the language appropriately, but language does not describe one person's private sensation. — Luke

I think Wittgenstein would say that recognizing a private sensation does not assist in using a word appropriately. Think of PI 265, the train time-table example. He might say using language correctly shows we recognize the private sensation (or maybe ….we experience the private sensation).

Notice that it's trivially true that feeling just is not concept. — plaque flag

Agreed, feelings are not concepts, but if you want to talk about feelings to your fellow human being there is a lot of set up that needs to take place. We simply do not take a literal picture of what is going on inside and give it to another person and say “see this is how I feel.” We need words associated with particular circumstances; we need a common language to understand those circumstances; we need our fellow human being to react similarly to those circumstances, or at least imagine how they would react, etc… with any luck we get understanding and empathy.

What accurately means depends on context. So if we give people the same color patches and they describe them using the same I words I use, then what more is needed to say they've described the colors accurately, and that they are seeing what I see? For all practical purposed their descriptions are accurate. There's no good reason to think they are seeing different colors. It's a problem without a difference. — Sam26

As Wittgenstein pointed out in PI 258, there is a problem talking about the accuracy of private sensations, he says towards the end, “But in the present case I have no criterion of correctness. One would like to say: whatever is going to seem right to me is right. And that only means that here we can’t talk about ‘right’.

What goes wrong with some much talk of private sensations is it borrows so much from the language of the public shared reality that words begin to loose their sense, like “right” “accurate”, “judgment”, “remember”, “something” etc… How much do you cut off a tree where it is no longer a tree but a stump?

At the very least I can say they are private experiences/sensations, and we often do describe such sensations accurately. — Sam26

What could “accurately” mean in such a case of private experiences/sensations. One, no one, in principle, can verify the truth of such an assertion, so why even call it is an assertion. Two, we learn what “accuracy” means by learning the techniques of determining the accuracy of whatever is under examination. Thus, no one can teach another how to determine the accuracy of a private experience/sensation. Lastly, Wittgenstein does not deny one have these experiences but only what can be said, which is not much at all. Just like if someone is in a completely dark room and someone ask “what do you see?” And one replies, “It is dark.”

When you see a "red" object your private subjective experience may be of the colour blue. — RussellA

I think this idea is confused based on the very idea on how we learn the language of color and language is general. Please consider this example:

For simplicity sake let us assume we are in a world with just two colors, red and blue. In my tribe, we learned when we see a red object we call it “red” and when we see a blue object, we call it “blue”. One day we travel to an island and we meet another tribe that surprisingly has a very similar language like ours with the exception that when they see a red object they call it “blue” and when they see a blue object they call it “red”. What are we to think in this situation? That they actually see a blue object where we see a red object, or that they simply call a red object “blue” in their language? We can easily ask for the red object by saying “Can you fetch me that blue object” in which they bring me the red object. Would it not be more reasonable to believe our words for “blue” and “red” are “inverted” not how we experience those objects? If this is so, how is this any different when someone says to me, I see that red object but I really see it as “blue.” It is not that we will never know what one actually experiences, but that we are going beyond what the language of color can express.

I understand why someone would claim this, and I readily agree that the social aspect is necessary. But I don't think it's exhaustive. Ought we deny our experience of intending an object ? Or intending a state of affairs ? Something like the direct experience of meaning ? I think training is crucial for the linguistic version of this, but once trained we have a certain independence and ability to introspect. — plaque flag

To reiterate what Wittgenstein says in PI 305, "But you surely cannot deny that, for example, in remembering, an inner process takes place." What gives the impression that we want to deny anything? When one says "Still, an inner processes take place here"-one wants to go on: "After all, you see it." And it is this inner process that one means by the word "remembering".-The impression that we wanted to deny something arises from setting our faces against the picture of the 'inner process'. What we deny is that the picture of the inner process gives us the correct idea of the use of the word "to remember".

In terms of "introspection", the idea of "introspection" is shown when we share are ideas with other language users, develop ideas with argument, listen to clarifying questions, see if others can apply our ideas, act on them, and even expand on them. What give "introspection" meanings is not what lies hidden within the self, but what is expressed and understood between others.

perceptual psychology indicating that what you are calling primitive reactions is in fact complex conceptual understanding. — Joshs

Long live theorizing, may you find some pragmatic benefit.

What about pre-linguistic perceptual meanings? Do pre-verbal infants not construct meaning from their surroundings through the use of perceptual-motor schemes? — Joshs

As human being, we have many primitive reactions that serve us well, like thirst, hunger, pain to name a few. But would we say that an infant has the meaning or the concept of “thirst”, “hunger”, or “pain” before they even learn these words from an adult. No, but they do experience these things and later, adults teach the infant to replace this behavior with language.

Private meaning is not made possible by public meaning. — RussellA

Do not agree. Public meaning makes private meaning incomprehensible.

We learn what “red” is by being expose to red objects and judging similarly. What goes on inside is irrelevant to the meaning of the concept “red”.
You ask someone to imagine a red object that is experienced by one person as “blue”, another “green”, and another “yellow”. For example, if I experience a red object as “blue” and blue object as “red” and another person experiences a red object as “red” and a blue object as “blue”, what has established the use of “red object” and “blue object” amongst language users? Private experiences of “blue” and “red”? No. Common color judgments of objects with other language users? Yes. In this example, everyone could be experiencing something different, but what holds it together is the shared judgment when exposed to a particular colored object.

Could it be that I have no experience of what we would call “color” but some other experience of a “private” kind? But what could that be and could it ever be communicated? Just saying it is different is not saying anything at all. This idea of “private meaning” is tempting but ultimately vacuous compared to where that idea of “meaning” has its life, among a group of language users talking about a shared reality.

There's a book I've noticed, Jerrold Katz, The Metaphysics of Meaning. (Reviews here and here). This book, and indeed most of Katz' career, was dedicated to critiquing Wittgenstein, Quine, and 'naturalised epistemology' generally. He also studied under Chomsky, but I think the basic drift is Platonist, i.e. meaning has to be anchored in recognition of universals as constitutive elements of reason - not simply conventions or habits of speech. — Wayfarer

I finally have had a chance to read this book. Thanks for mentioning it. I have not seen many sophisticated attempts that try to argue against later Wittgenstein, but this is one of them. On the positive side, Katz does a great job of elucidating both Wittgenstein’s and Quine’s philosophy. In fact, most of the time he agrees with Wittgenstein’s investigation into meaning and language. However, he believes, Wittgenstein’s criticism does not touch certain linguistic attempts at discovering the underlying structure of language. Additionally, he believes Platonic versions of philosophical theories can explain those linguistic proto-theories better than the naturalistic positions that Wittgenstein and Quine offer.

In the end, he believes he has shown that his vision is a justifiable alternative to the naturalism positions he attempt to critique.

Obviously Av~A is true and A&~A is false. — A Realist

Well that depends.Take A&~A is false. How so? There is a symbol A and there is a symbol ~A thus it is true. Or substitute for A “I am in pain”, in the case Av~A is false because ~A is not sensical so the “or” cannot function if utter in the situation of expressing pain.

Wittgenstein doesn't make this distinction, at least not clearly, but I do. We act in the world with a certain conviction that things are the way they are, and it's not a matter of justification as W. points out in PI 325. And, it's through these actions that these very basic beliefs (other philosophers refer to them animalistic beliefs) are seen. — Sam26

I find it strange to say a basic belief is “I have two hands”. Not only is absurd to say “I doubt I have two hands”, but also “I believe I have two hands” or “I am convince I have two hands”, when, in fact, I have two hands. If other people would start challenging me on this, I would think they have gone mad, or psychologically manipulating me for some reason. Additionally, if one would say, “Well I could imagine that you have been drug and your hands have been amputated, yet you feel certain that you have hands.” My response could be, So what, just because you could imagine such a thing does not make it possible, it could be that I am immune to such drugs and hallucinations. Lastly, why are we calling something “knowledge” as something that excludes possible doubt. This seems too unnecessary of a high bar for a concept that is use in everyday life. It seems Wittgenstein could not cure himself of this philosophical view of “knowledge.”

No, we don't justify that we have hands through sensory experience. Is that how you came to believe you have hands. — Sam26

But we justify orange juice is sweet by our taste? You seem to be inconsistent here.

In my example, I am not speaking in front of skeptical philosophers who are doubting the external world. I am a job applicant who is being ask if I have two hands because the job requires two hands to operate the machinery. I can answer yes or no. If one of my hands was amputated due to an injury the answer is"no". In this circumstance, this can be counted as a statement of knowledge.

The statement that "I know I have hands" is just epistemologically wrong — Sam26

.

Not in general, it depends on the circumstance.

What would it mean to doubt that you have hands in Moore's context? — Sam26

Agree here that the use of "doubt" is questionable in Moore's context. But why could we not say that Moore is justified in saying "I know I have two hands." by just showing the audience such objects.

In PI 325, Wittgenstein says the following, 'The certainty that I shall be able to go after I have had this experience-seen the formula, for instance,-is simply based on induction.' What does this mean?- 'The certainty that the fire will burn me is based on induction.' Does that mean that I argue to myself: 'Fire has always burned me, so it will happen now too?' Or is the previous experience the cause of my certainty, not its ground? Whether the earlier experience is the cause of the certainty depends on the system of hypotheses, of natural laws, in which we are considering the phenomenon of certainty. Is our confidence justified? - What people accept as a justification is shown by how they think and live."

Is not this the case with Moore when he shows the skeptical philosopher his hands thus demonstrating the absurdity of doubting such a thing?

Why would you ask this? — Sam26

I have a job that requires someone to have two hands to operate a piece of machinery; so on the job application I declare “I have two hands.” Is this not providing my knowledge of my biological state to someone who can confirm my assertion?
— Richard B

No, and this Wittgenstein's point, i.e., it's not a matter of epistemology, generally speaking. — Sam26

So is this not

We justify knowledge claims based on sensory experiences. — Sam26

?

So what is a “statement of knowledge”? Can you provide an example?

If you can’t, what distinction can one be making between “ a conviction” and “a statement of knowledge”

One of the problems with Moore enumerating what he knows, is that it seems to amount to more of a conviction of what he believes, than a statement of what he knows. How does this happen? — Sam26

OK, a distinction is being made here, a “conviction” vs “a statement of knowledge”? Declaring “I have two hands” falls under the category of “conviction” But Wittgenstein finds this odd to say this in front of a bunch of philosophers rather than saying it after, say, a car crash. Should it even be called a “conviction” when our concepts have been removed from its common use? What about whether this is an example of a “statement of knowledge”? Again, what circumstances would this become knowledge? I have a job that requires someone to have two hands to operate a piece of machinery; so on the job application I declare “I have two hands.” Is this not providing my knowledge of my biological state to someone who can confirm my assertion?

Why? Because if you add to the concept existing in reality you would still just have a concept existing in reality, not the being itself.

Finally, many find the argument dubious for other reasons, viz., trying to prove the existence of something from the concept alone, which others have pointed out in this thread, is very problematic to say the least. — Sam26

I believe Anselm is trying to distinguish between two different ideas, "understanding that something exists in reality" and "experiencing that something exists in reality." As he says in Chapter 2 "And so. O lord, since thou givest understanding to faith, give me to understand-as far as thou knows it to be good for me-that thou exist, as we believe, and that thou art what we believe thee to be."

Unlike the painter and painting example, where producing a painting is the reason he understands the painting exists in reality, it is the idea of "a being than which none greater can be thought" and its deductive implication that Anselm understands such a concept of a being "exists in reality." So, when you say, "....you would still just have a concept exist in reality, not the being itself.", what is this idea trying to express? That the deductive argument should produce some experience of "the being of God"? Demonstrate some experience we had corresponds to this idea of "a being than which none greater can be thought."? It is a deductive argument, it is about ideas. Geometric proofs are about ideas, which does not mean it will have any successful application in reality.

Whether the argument is sound, how can we fairly access this? How does one evaluate the "truth" of "God is a being than which no greater can be thought", and "Existing in reality" is greater than "existing in understanding" in order to determine soundness. What should we do, take a poll on how many people agree with these premises?

Maybe what this argument ultimately demonstrates is the vacuousness of using general concepts and deductive reasoning whether one thinks something exist or not.

That experience is the final arbiter.