You are correct in that you have no immediate reason a posteriori to believe in the existence of the world in the absence of perception. It is still the case you have mediate reason to believe a priori, in the existence of the world, iff you’ve a set of cognitions from antecedent perceptions. And it is impossible that you do not insofar as you’re alive and functioning, so….. — Mww

But can the world be the object of a priori knowledge? When you say precedent perception, could it be memory? Doesn't memory tend to be unreliable for qualifying as a ground of infallible knowledge or justified belief?

The fact that someone is living and functioning doesn't mean that the folk have infallible ground for the existence of the world, does it? All he might be interested in his mind could be the football results on TV, or his stag night plans with his pals in coming weekend. These are the people whom Hume calls the "vulgars" in his Treatise. They would not even understand what the question or issues are with the scepticism regarding the external world.

As you said, most folks in ordinary daily life don't bother or care about the reasons to believe in anything. They just do.

Everydayman doesn’t bother himself with believing in so obvious an existence, any more than he bothers himself with doubting the non-existence of it.
For the philosopher or the scientist, it is quite absurd to suppose either of those merely believe in that existence the ignorance of which, for them, is impossible.
Which begs the question….who else would even wonder about it? — Mww

Some folks seem to think, why is this issue important or significant? I think it is interesting and significant because perception is perhaps the most important thing in leading a meaningful and trouble free life. Not just for human beings, but even for the animals on this earth.

Suppose that if a dog cannot tell the difference between a cat and tiger, and when he saw a tiger, if the dog chased the tiger barking thinking it was a cat, then he would be eaten fast by the tiger, and no longer exist. But the matter of fact is that, even a dog would perceive the tiger, and know the imminent danger, and run away as fast as he could hiding for his own safety.

For human beings, if you drive a car when you are not perceiving the road ahead of you, believing that it exists even if you are not perceiving it, and keep on racing away into a river, then that would be a disaster. When you don't perceive the road ahead of you, you simply say to yourself, you no longer have reason to believe there is a road ahead of you, and get out of the car, and take a taxi home. Wouldn't it be a more rational thing to do?

Corvus, I want to share with you some notes from Kelley Ross, when he finished his dissertation. My aim is not to force you to believe on the existence of the world, but to see another prospective in its prism. Ontological Undecidability — javi2541997

Hello Javi.  Thanks for your quotes from the article, and points.  It is very helpful, and interesting. It is interesting that the author of the article sees Kant's Thing-in-Itself as objects beyond human understanding.  Once upon a time in the past, I too, was looking at the concept that way.  

Would it make Kant an idealistic dualist?  The dualist who thinks that there are two different worlds i.e. Phenomena and Noumena. It is also an idealistic world view because the world is in the mind of the perceiver i.e. without the perceiver, the world doesn't exist?  Would this be the right interpretation for Kant?

But, if we are not directly acquainted with the real objects of experience, and they exist, then the real objects of experience are separate from us. — javi2541997

The point of the OP was not that I don't believe in the existence of the world when not perceiving it, or trying to deny the existence of the world as such. But I was trying to see what the logical grounds are for our belief in the existence of the world.

This epistemic problem has been dogging the philosophers from the ancient times, and in the modern times Hume and Kant as well. They have been propounding and analysing the issues in their work extensively. But I was wondering, if the old problems regarding the scepticism have been sorted out with some concrete resolutions in recent times and even now as we are discussing the issue in here, or is the problem still hanging in the air with the same controversies as long before in the history of Philosophy from the ancient to the early Modern times.

Is our belief in the existence of the world based on some logical evidences and reasonings based on the perception?  Or is it by inductive reasoning? Or would it be just habits, customs or animal instincts?

Academic Skepticism in Hume and Kant: A Ciceronian Critique of Metaphysics by Catalina González Quintero (Author)

The book is divided into three parts i.e. Scepticism in the ancient Greek times, Humes' Scepticism and Kant's Scepticism. It is clearly written, and looks at the methodologies and details of the Scepticisms from different angles, which is interesting.

Perception is not based on logical inference. — L'éléphant

So what are our perceptions based on, if not on the logical inference?

If you're looking for the logical grounds for believing in the existence of the world, then what better way than your own thoughts in refusing to believe. Someone, like you, who refuses to believe in objects not existing is the best, surest reason for believing there's something. You exist. — L'éléphant

I don't have to refuse or agree to believe. But could I not just say I don't have a reason to believe, when there is no reason to believe? I don't deny my existence when I am awake and perceiving the world, because if I didn't exist, then the perception would be impossible.

But then again, when I am asleep, I don't have a ground to believe that I exist. Do you have reason to believe that you exist, when you are in deep sleep? If yes, what are the reasons for your belief? How can you think about the reasons that you exist while in deep sleep?

It wasn't.

But I definitely took a picture and left a message. It remains in my mind, and now in yours. But neither of us can access it physically, here and awake, that is. So what does that mean? — Outlander

It sounds like you had a real vivid dream, which felt to you like real life happening. When you woke up, and tried to verify if it was a real life event or not, it was just your dream event. So, could it mean that we might all be dreaming right now? How do we tell the dreams from the real world, or real life events from the dream events?

Is it possible for you to be not perceiving the world while you are still alive? Would this be when you are asleep? But don't things still wake you up? Are you not in some way perceiving the world even when you are asleep? — Metaphysician Undercover

When one is alive, and perceiving the world, of course, one believes in the existence of the world, because one has the ground for believing in the existence of the world.  But when one is dead, or asleep, there is no longer perception for the individual.  Therefore could it be the case that there is no reason for the individual to believe in the existence of the world? Would you say that one should believe in the existence of the world, when one is dead or in deep sleep?

If I understand your point correctly I’d say we have far more reason to believe in the objective existence of the world than not. The onus is on the person that says it isn’t real, a simulation etc. — Captain Homicide

So what are your reasons and proofs for believing the world exists, when you are not perceiving it? What is the ground that says, something isn't real? How do you tell something is a simulation, rather than real?

I am interested in seeing the logical reasons for believing in existence of the world or objects without perceiving them. It is not about the actual world or objects, but the thinking process for the reasons of our beliefs in existence.

Are our beliefs in the existence of the world or objects based on some logical reasoning? or is it just all groundless, habits and customs to believe in these things?

If you are typing this and asking others for opinions, aren't you committed to the existence of the world? — Tom Storm

As I am typing this, I am perceiving my surrounding objects and the world around me vividly. So yes, I am believing in their existence for sure.  But I don't have any reasons to believe in anything else in this world I am not perceiving.

One may notice problems, but why extrapolate from them the notion that such problems are ubiquitous, regardless of considerations of context? — Ciceronianus

But isn't Philosophy about finding out the nature of the world, our knowledge of the world, and the limitation / boundary of our knowledge? What would your points of Philosophy be?

Sure. A great point. :up:
Although I recall Hume had problem with induction for being circular or question-begging type of reasoning.

From my point of view, if someone had a bad memory or have had little or not enough experience of the observations, induction doesn't work for him. In these cases, inductive reasoning cannot be a good ground for believing in something. If there is a possibility of even one failing, then it cannot be a law or principle.

Hume seems to be in the position that inductive reason (because it is based on habit and customs) can only offer us probable knowledge of the world, hence it cannot be a good ground for believing in the world.

Of course, it is not logically contradictory that things should cease to exist and then come back into existence again, but considered against the whole body of science and everyday observations it is highly implausible. — Janus

There are many sceptical discussions even on the whole body of scientific knowledge for their validity, because all scientific knowledge is obtained from the phenomenon i.e. sensibility via observations. Obviously there are problems in the certainty and accuracy of the scientific knowledge too. Even Science cannot escape from Scepticism. This is a totally separate topic. Maybe you could start a new topic with this issue.

You still don't answer the question. So you still believe that you would have to accept the counterfactual if you did and that you would then have to admit that it is a ground for believing it exists when you don't perceive it. — Ludwig V

So let me ask you this time. I have asked you this question many times, but you have never answered for it yet.

What is your reason to believe in the existence of the world, when you don't perceive it?

That may well be. And it may be that a desire for absolute certainty is behind the effort. But I still think the fact such skepticism is so contrary to how we live our lives that it should count against it, so to speak. If inductive reasoning (for example) is something we "have to do" by virtue of living, what induces us to think that there's no basis for it? Why question it in the first place? — Ciceronianus

Wouldn't it be due to the nature of our reason? When reason reflects on itself, it cannot fail to notice the problems in the existence and the knowledge of existence.

You still don't answer the question. So you still believe that you would have to accept the counterfactual if you did and that you would then have to admit that it is a ground for believing it exists when you don't perceive it.

The next question is whether you accept that you exist when you are perceiving an object and whether you perceive yourself when you are perceiving an object. — Ludwig V

I would go with Hume. There is no reason to believe in anything when I don't perceive, be it the world or myself. That doesn't mean that I don't believe in the world or myself. I keep asking you to know the difference between the two cases.

I'd never heard of this mechanism. Those psychologists are so clever, with names. — Ciceronianus

It was just a passing impression. Not a judgement. No worries.

How odd, and revealing, it is that Hume thought he didn't exist while he slept. How was it, you think, that he tried to "catch himself" without a perception? Did he try to "sneak up" on himself so to speak, only to find that he was aware he was doing so and continued to see, hear, smell, etc.? What would have been the case if he succeeded? — Ciceronianus

I had to answer the similar question on the other thread. I understand Hume's scepticism as his endeavour trying to find the ground for certainty and warrant for belief in the existence of the world and self, not the actual existence itself.

You repeat your claim three times but don't answer my questions.
Do you accept that if you were to turn and look at the cup that is holding your coffee, you would see it? Is that not a reason for believing that it still exists?
— Ludwig V — Ludwig V

Of course, I see the cup when I turn and look at the cup. The perception is coming in vividly.
But do you not see the difference that there is now the firm ground for believing in the existence of the cup, instead of not having the warrant that the cup's existence when not seeing it?

In defense of Corvus, he says he has on order Catalina González Quintero's — Fooloso4

I am not sure if there is any point to trying defend anything against someone who didn't understand what self-contradiction statements are, but claim to understand performance contradiction. I was under impression that he was going to go through all the arguments that I went through with Banno AGAIN with the whole load of self-contradicting questions, and was wondering what the point was.

I do not know this work or what he will get from it. Perhaps after reading it he will modify his claims or give us reason to rethink some of our own. In any case, even if we disagree with what he will say or Catalina González Quintero says, it demonstrates an attempt to become better informed about such things. — Fooloso4

I am not sure either. But I thought it would be interesting to read somebody whom I have never come across as Kant commentary scholars before. I was presuming maybe there might some new interesting insight in the book. Will be able to tell more once I finish the book. Who knows.

I am not claiming that I am an academic sceptic. Most of my ideas comes from my own reasoning and little amount of casual readings on the textbook and commentaries.

Since appeals to Hume and Kant and academic skepticism will take us too far from the topic of this thread I won't pursue it here, but I would be interested to read what you have to say if you start a thread on Hume and Kant and their connection to Academic Skepticism, and more specifically your claim that: — Fooloso4

Sure. This is not the main topic in this thread. So I will bow out, and let them carry on. I have been only responding to the questions and posts directed to me.

I will read the book when it arrives, and will open a new thread on it, if there are interesting points on the subject. Thank you for your post.

And yet both you are Hume write for an unperceived public.

How long must the lights stay out before this form of skepticism takes over? Do you doubt the existence of the world each time you blink? — Fooloso4

Blinks don't take long time enough to make the world to totally disappear. Does yours?

We are talking about what is called Academic Scepticism allegedly practiced by both Hume and Kant, which I am trying to learn more (waiting for the book to arrive).

It is about the warrant of belief, not the existence itself. This is an Epistemological issue, not ordinary life issue.

This is true. What it shows is that in order to live, you have to be irrational. — frank

It shows that the sceptics have been scorned for their rationality by the naive folks. :chin: :roll:

I agree that scepticism is a fundamental starting-point for this debate. But there's a question of the burden of proof. Your challenge to me is to provide a reason for believing that the cup that holds your coffee exists when you don't perceive it. Do you accept that if you were to turn and look at it, you would see it? Is that not a reason for believing that it still exists? — Ludwig V

I mean we have no ground, warrant or reason to believe in the world, when we are not perceiving it.
The ground, warrant or reason for believing in the world is the perception of the world.  But when you are not perceiving it, there is no more the ground, warrant or reason to believe it.  That is from a logical reasoning.

But people keep believing in the world when they are not perceiving the world.  They are believing it without the ground, warrant and reason for believing it.

So what is more rational?  I would say stopping believing in something when there is no ground, warrant and reason to believe it would be definitely more rational than keeping believing in something when there is no ground in believing it.

This was what Hume was propounding in his Treatise, and that point of Hume was what Kant described as "a truth which awakened him from dogmatic slumber." I cannot be sure on the accuracy of this point now without checking it again.  But I am assuming that was what Kant said. Please correct me if I am wrong here.

"Scepticism is what keeps Theory of Perception ticking", as said by Barry Stroud (a late Canadian Philosopher), and I think he is right.

Well, following Immanuel Kant, this is my idea of stupidity. How would you define it? — Matias

Stupidity is a tendency to judge other peoples' intentions and characters with groundless delusional beliefs, and seeking attention, approval and self-pleasure with like-minded folks in group.

After reading the OP and its supporters posts, it reminded me of a severe case of Projection Defense Mechanism symptom in Psychology.

One of the extreme cases of Scepticism was by Hume. He even doubted his own "self".  But we don't call him someone who indulged in affectation.  

"I never can catch myself at any time without a perception, and never can observe anything but the perception. When my perceptions are remov'd for any time, as by sound sleep; so long am I insensible of myself, and may truly be said not to exist."  (Hume, Treatise)

Yeah, well, I’m still on your side, though we’re both technically outside the boundaries of the discussion. — Mww

:ok: :cool:

Right. I don't think Austin is arguing with that, although it may seem that some posters in this thread are. He was taking issue with a theory of perception transmitted by Ayers, which says your knowledge of external entities is built up from smaller units of perception called "sense data." — frank

I am not sure if perception or indeed any mental events could be reduced to the brain from Epistemology and Metaphysical perspectives.  It cannot be denied that the brain is where all the mental events happen, but from that boundary we are entering the physiological and neurological land, which are the foreign territories.

There are lots of issues that can be talked about at the conceptual level on mental activities since ancient times, and that is what we have been doing, and I don't see much changes in the near future for that trend to change as far as speculative Philosophy is concerned, and I am happy with that.

For sense data theory of perception, I feel that it is more reasonable than any other theories of perception.  When I see an object in the world, many times I am not sure what it is at first, when they are some distance away.  All I get is the extension and colour of the object. 

The extension is in the space and time, but the colour is a property from my consciousness, so there is some synthesis going on in perception. At this stage of the perception the object is nothing more than data i.e. I know the shape, colour and the location of the object (i.e. on the grass of the garden). I can further go and look close into the object and try to find out what it is looking for more data on the object. 

But even if it was found out to be a tree leaf, if I keep asking questions on it, there are more facts I don't know about the leaf i.e. which tree did it fall from? Was it indeed from the trees in the garden? or Was it blown into the location?  How long was it there? So, I never get absolute full information about the leaf, and in that sense, it still remains as data.  Data is also, by definition, information that can be stored and retrieved for further manipulation, which is coherent with perceived data, because we remember, imagine and reason with the perceived data after the perception.

This is the case even when I pick up a cup with my hand and look into it. Of course it is a cup, but at asking where it is made. what it is made of, who made it, or which factory made it, what is the diameter?, the weight? ... etc. Of course some information will be available if I go and measure the diameter with the ruler, and weigh it on the scale, but many information still remains unanswered. It is a data. For some naive direct realist, it is a cup, and that's the end of story for them. For me, there is a lot more I don't know about the cup. It is a data needing more investigation if need be, and possible to find out more information on the data in due course. Because a cup is a cup, not just because it looks like a cup, but because it has the extensive properties (some are in the form of essential properties and some are informational properties) attached to it for being a cup.

Anyway, I feel in that sense, Austin's endeavour trying to criticise or deny Ayer's Sense Data theory had been in vain.  Asking how we talk about perception is interesting, but it wouldn't make our perception have more certainty in perceiving.

It would have been more meaningful if Austin came up with his own definition and theory of perception before criticising Ayer, but it doesn't appear to be the case.

Thanks for your elucidation. Clear and precise analysis. :cool: :up:

I don't think your perception is infallible. LSD is not a "true" hallucinogenic, which means you know at the time that what you're seeing isn't real. For instance, I had an incident where I observed that the moon was following me around. I knew that wasn't real, though. — frank

Sure, I don't claim my perception is infallible. As a sceptic, in fact I even doubt my own perception. But it is the most reliable source of knowledge for me.

And the 2nd reason that I don't believe in the objects in the world is that there is a possibility that my perception was mistaken, it could have been an illusion, the tree I thought existed was cut down by someone while not being perceived by me, and not there anymore, or it could have been hit by lightening, and burnt down to ashes (and I am certain that it wasn't someone's words or shoutings that caused the burnt down - no, no. That would be an irrational belief or claim, if not insane ) ... etc. I am open minded about all the possibilities that existence can succumb to at anytime. I think it is a rational belief to have.

You might believe the tree exists because a trusted friend told you so, and on the other hand, your perception might be delivering false information to you if, for instance, you have taken a hallucinogenic drug. So, though it's true that if you perceive a tree, it's rational to believe there's a tree, it's probably not the only grounding for such a belief, right? — frank

hmmm being a sceptic, I am afraid I don't base on any of above case as the logical infallible ground for the existence of the tree apart from my own perception. Maybe some other folks might. Not me. :)

Ok good point. This is my argument.
The logical ground for me to believe the tree exists across the road is that, I have perceived its existence. There is no other ground for me to believe in the tree to exist apart from the perception.
But when I don't perceive it, I don't have that ground to believe it still exists. It might well be existing, but with no perception of it, there is no ground for believing it anymore.

Normally people still believe the tree to exist when not seeing it, because that's what they do.
But as I don't have a ground to believe in its existence, I can choose not to believe in its existence.
Now which belief is more rational? I would say my belief is more rational than the ordinary peoples' belief, because their belief has no ground, but I chose not to believe in its existence when I don't have a logical and epistemic ground to believe in it.

So the whole point of argument was about the logical ground for belief in the world, rather than the existence of the world itself.

You seem to have missed the point.

When we sleep, we are not perceiving the world.

Now apply the example I offered. It is of a case where someone we're watching is sleeping, and the world still exists even though they are not perceiving the world. The same holds true of the world and you while you sleep. — creativesoul

The point is that we are talking about a logical ground to believe in the world when not perceiving the world.  Please ask yourself, what is your logical ground for believing in the world when not perceiving the world.  Please don't say the world exists even when you are not perceiving it, because it is not what we are talking about here. We are talking about the basis for scepticim regarding the external world.

You're mistaken here. "change the tree on the road with our words alone" is not equivalent to "change the world with our words". In other words, you've assigned the same variable "Y" to two different things and then treated them as the same thing. They're not.

See that word "alone"?

Words do not cut down trees. Words can instruct another to cut down trees... using language to do so. — creativesoul

But did words cut the tree itself? What tools did the words use for cutting down the tree?
OK, you say now you gave instruction to cut down the tree. Did the tree surgeon cut down the tree without any payments for it? If you gave the instruction to cut the tree, but haven't paid for the work, would he have cut the tree?

What if the tree surgeon refused to cut the tree, because the tree is not allowed to be cut due to the local conservation laws. What if he misunderstood your instruction, and cut the tree in next door neighbour's garden instead? But more importantly, did you give the instruction to cut the tree out of blue with no thoughts why the tree needs cut?

Again you could insist on saying that your words in the instruction caused the tree to be cut, but with all the above possibilities with the situation, are you actually justified to claim that it was your instruction which cut down the tree? Some people in ordinary daily life might say that, but you must be aware of the fact that here we are talking about rigid philosophical analysis on the change of the world, not daily life conversations.

The bottom line here is whether logically, if a hammer is the broken door. You used a hammer to repair the door. But the hammer is not the door. If you said that they are the same, I don't see any more point honestly.

Anyhow, I have gone over this same stuff with Banno all along, and I don't see any point of doing so again with yourself. My points are clear.

1. We don't have a logical ground to believe in the world while not perceiving it.
2. Words are not actions.
3. Words are not things.
4. Language is a communicating tool.
Have a nice day.

The last claim above does not follow from the bit that precedes it.

Think of when you've watched another sleep. People sleep. We watch. We're part of the world. The world exists while they sleep. If you agree, but still doubt your own experience, then you're working from double standards. Special pleading for your case. — creativesoul

It wasn't about other people sleeping. It was about the question, do I believe the world exists, when I am asleep? The point is not about the existence of the world. It is about the logical ground for believing in something when not perceiving. There is a clear difference.

We cannot change the tree on the road with our words alone. It does not follow from that that we cannot change the world with our words. Strictly speaking we do always change the world with our language, if for no other reason than we've added more examples of language use to it. — creativesoul

X cannot do Y. That doesn't mean X cannot do Y? Is this not a contradiction? This is exactly the confusion I have been telling he has been insisting on. :)

The point is that we do sometimes use language to do exactly what you said, but... and this is the important part... — creativesoul

Literally you could say anything. But that alone doesn't change anything in the real world. You need action to change the world. I take it that you have never cut your grass by yourself in your life for sure. :rofl: How nice it would be if you can change the world by your words alone. :roll:

You could say your words caused the action to happen. But you forgot the words were just expression (a communicating tool) of your thoughts, emotions and intentions. Not the actions. I hope that you are more reasonable than Banno in understanding and accepting this point. If not, it is OK. I gave my opinion for the points, as you asked for it.

You don't say "The tree was cut down by my words."    It sounds just not right.
You would say, "The tree was cut down by the tree surgeon."  

Good stuff. "This was Austin's most important idea: All utterances are the performance of speech acts" — Banno

Speech Act Theory seems to have problems. It confuses word utterances from actions just like you have done. Now I know where your confusion is coming from.

If you asked Searle "Who cut the tree?", he would say "You ordered me to cut the tree, so it must be the words in the order sir."

OK, I still think words are not actions. And words are not things. Saying they are same sounds not making sense.

And the repairing tools are not the broken doors to be repaired. Saying they are the same sounds illogical.

No. I think most folk here understand Austin. You are an exception. — Banno

I never claimed I understand Austin in full.

Obviously. It probably has not been pointed out to you before that we do things with words. A Big Learning for you. — Banno

Yeah I gave you the reason why I don't agree with your points. I would have thought you would admit the problems in your statements which are full of confusions and contradictions.

Given this, there is no way that you will be able to understand Austin. You've just got the perception stuff far too embedded in your thinking. It's a bit sad that you have been so mislead, but them's the breaks. — Banno

Austin's writing is very clear, and his points are logical.  Anyone reading Austin will have no problem understanding him.  For some reason you seem to think, no one can understand Austin. 

Words are actions. We do things by speaking and writing. Your view of language is far too passive. — Banno

Hmmm I don't agree with you at all. You are still confusing the tools with the broken door. :(

You say that as if the order can't change things. And yet it does. — Banno

But you don't see the fact it was the action which changed the tree not your word.

There's a curious myopia amongst those who see language as only "communication" or "information exchange", such that they have a great deal of difficulty seeing how words are actually used by people to build the world. Property, ownership, money, exchange, promises, hierarchies, the everyday paraphernalia of life is constructed by language. — Banno

Another confusion between words and things. :roll: You still seem to be hiding in Austin' well, and cannot see the world out there just staring at the well wall.

Given this, there is no way that you will be able to understand Austin. You've just got the perception stuff far too embedded in your thinking. It's a bit sad that you have been so mislead, but them's the breaks.

You do know that the world continues while you sleep. Right up until you try to do philosophy.

So I might leave this conversation there. — Banno

There is a difference between having no logical ground of believing in the existence of X, and the actual existence of X. Please think about it carefully again. Leaving is fine. It just confirms you ran out of the ideas for the arguments. What can anyone do about it?