, it's safer to think that what you won't know can still kill you.
But hey, you won't find any purely deductive disproof of solipsism either.

it's safer to think that what you won't know can still kill you.
But hey, you won't find any purely deductive disproof of solipsism either. — jorndoe

Sure, I find Hume's argument interesting, which I am going to read further. Whether he was denying the world or not, is not really important for me at all.

It is also interesting to look into more on the concept of "the world" and "existence" and dissect them further. Questions such as, is it logically correct in saying "The world exists."? What does the predicate "exist" entail? What is the definition of the world?, arise as the secondary issues.

is it logically correct in saying "The world exists."? — Corvus

Might be interesting how that even came to be a question.

Hume displays a slightly faulty way of understanding sensation. — Metaphysician Undercover

Any relevant quotes from Hume? — Corvus

What do you want me to do, quote all the places where Hume is wrong?

Look at his Treatise of Human Understanding Bk 1, Sec 4, part 2 where he discusses the skepticism in regard to the existence of body, for example. The issue is stated as the continued and distinct existence of body. He proceeds from his earlier described premise, that sensation produces "impressions", and says "...they convey to us nothing but a single perception... ", p189. What I argued is that this is a simple misrepresentation. The senses do not provide us with any individual impressions like that. There is a multitude of senses active all at the same time, and time involves duration, so what the senses are sensing is itself activity, not single perceptions. The 'activity' which the senses are actually directed toward, then gets misrepresented by Hume, as what occurs in between the distinct instances of single perceptions, making a temporal succession of instances of perceptions, the sensations of single perceptions.

The problem is that Hume has actually reversed the roles of sense and mind here. The senses actually provide us with a continuity of activity, extended in time, which is only broken by turning one's attention away from the world being sensed. But Hume represents the senses as producing "single", distinct and individual impressions, which are already divided into discrete units, instead of properly representing the senses as providing the fundamental continuity of activity, which is only broken by the mind imposing interruptions to the continuous act of sensing. Notice in the following quote, how he begins from the assumption of a multitude of individual "impressions" provided by the senses, rather than the continuous activity which the senses actually provide us with.

First, That, properly speaking, ’tis not our body we perceive, when we regard our limbs and members, but certain impressions, which enter by the senses ; so that the ascribing a real and corporeal existence to these impressions, or to their objects, is an act of the mind as difficult to explain, as that which we examine at present. — Hume, Treatise of Human Understanding, p191

@Corvus
Check this reading group: https://thephilosophyforum.com/discussion/13614/reading-group-humes-of-skepticism-with-regard-to-the-senses

You seem to be a master of missing the point. The argument is simply that the existence of the world independently of its being perceived is an inference to the best explanation for our experience. It isn't a proof and doesn't purport to be.

As I read Hume all he was doing was pointing out that inductive and abductive reasoning are not deductively/ logically certain; a move against rationalism.

In respect of the question posed in the OP, it might be recalled that the 'knowledge of the external world' was the subject of an often-quoted passage in the Critique of Pure Reason, to wit:

It still remains a scandal to philosophy and to human reason in general that the existence of things outside us … must be accepted merely on faith, and that if anyone thinks good to doubt their existence, we are unable to counter his doubts by any satisfactory proof. — Kant, Critique of Pure Reason, B519

Bear in mind that in the context, Kant was addressing his philosophical predecessors, including Berkeley, who famously stated esse est percipe, and Descartes whose cogito argument stated that knowledge of one's own being was the foundation of all certain knowledge. I think they were the kinds of sceptical challenges he was referring to.

As is well known, to rebut this scepticism, Kant argued that knowledge is not grounded solely in sensory experience (empirical knowledge), nor exclusively from logical reasoning (rational knowledge). Instead he shows that the understanding is a function of the unavoidable way in which the mind structures the stream of sense-data according to the categories which are innate to the intelligence. Referring to "a priori" (knowledge that is independent of experience) and "a posteriori" (knowledge that is dependent on experience), Kant claims that space and time are not solely objective in nature, but rather grounded in the forms of intuition which are inherent in the structure of cognition. Accordingly he claimed that while we can never know objects as they are in themselves we can know them as they appear to us (the phenomenal world). But I think it's fair to claim that this does not reduce empirical knowledge to illusion or fantasy. Kant was an empirical realist, but not, in today's terms, a scientific realist, because he would obviously dispute the tenet that the objects of knowledge are truly mind-independent. But the distinction between Kant's transcendental and Berkeley's subjective idealism is quite a subtle matter. I think Kant's might be described as being a kind of 'qualified realism' - that what we see really is there, but that it's also inexorably dependent upon the eye with which we see it. That 'things conform to thoughts' was the Copernican revolution of Kantian philosophy.

My take is that the subjective nature of time and space are the cornerstone of the framework. But I don't think he claims that these are 'merely' or 'only' subjective, in the sense of being peculiar to the individual. Rather that they are grounded in the human mind, so, if you like, a kind of 'universal subject' rather than an individual ego. This is where Kant's 'transcendental apperception' is significant ('experience both of the self and its objects rests on acts of synthesis that, because they are the conditions of any experience, are not themselves experienced'). It's an antidote to the kind of hyperbolic objectivity that science is inclined to foster (many argue that it culminates in a kind of hyperbolic subjectivism, although I don't agree with that.)

//ps// and also Hume's scepticism should be mentioned which was principally scepticism of the knowledge of causal relationships. This was the subject of Kant's answer to Hume which is a unit of study in its own right.//

is it logically correct in saying "The world exists."?
— Corvus

Might be interesting how that even came to be a question. — Mww

Kant says that the World is totality all appearances in the universe (CPR, Antinomy of Reason), therefore it belongs to the subject of Cosmology. It is illogical to say "the World exists." Because pure reason cannot grasp totality of all appearance in the universe.

You seem to be a master of missing the point. The argument is simply that the existence of the world independently of its being perceived is an inference to the best explanation for our experience. It isn't a proof and doesn't purport to be.

As I read Hume all he was doing was pointing out that inductive and abductive reasoning are not deductively/ logically certain; a move against rationalism. — Janus

I am not sure where you read Hume from, but it doesn't sound as if there is any truth at all in your points.  Therefore I will give it a miss on that. :D

I have a few commentary books on Hume, and all of them have substantial amount of writings on the topic i.e. Hume's scepticism on the External World.  In fact there are a few books devoted to Hume's theory on the External World e.g. by H.H. Price.

Personally I do feel that, Hume's Scepticism on the External World is the most interesting part of his Philosophy, and it has a good amount of arguments and proofs in it. It is not just a 2 line google search results amount as you claim.

Just to give you simple hint or summary of his arguments and proof, his Treatise Hume devotes a full section called "Of the Scepticism with Regards to Senses" to discussion on the Perception of the External World.  He divides his arguments into 2 parts.  One from the Vulgar(Ordinary People)'s point of view, and the Philosopher's point of view for the other.

He argues that the ordinary people believe in the existence of the external world when not perceiving it, and it is based on the idea that the objects have distinct existence from perception. Because objects have distinct existence without perception, the vulgars (ordinary people) believe that the objects have continued existence while not being perceived. And because the objects have continued existence, it is also distinct in existence (i.e. exists without perception)

But in Hume's system for an object to be distinct, it has to be the perception of the object, because all objects are impressions.  Nothing can be perceived without impression, so the distinct object in existence must be an UNOWNED floating impression.   But it is impossible for impressions to be unowned or floating logically.  Hence from Modus tollens,

If CE then DE 
not DE 
therefore not CE

It follows that the vulgars' belief in the existence of the external world is false.

He goes on proving Philosopher's belief in the existence of the external world, and concludes that the belief cannot be based on reason, but imagination.  There are extensive arguments and proofs why this is the case.

Therefore your post seems to have been based on false information of you readings or your misunderstanding on Hume.

My take is that the subjective nature of time and space are the cornerstone of the framework. But I don't think he claims that these are 'merely' or 'only' subjective, in the sense of being peculiar to the individual. Rather that they are grounded in the human mind, so, if you like, a kind of 'universal subject' rather than an individual ego. This is where Kant's 'transcendental apperception' is significant ('experience both of the self and its objects rests on acts of synthesis that, because they are the conditions of any experience, are not themselves experienced'). It's an antidote to the kind of hyperbolic objectivity that science is inclined to foster (many argue that it culminates in a kind of hyperbolic subjectivism, although I don't agree with that.)

//ps// and also Hume's scepticism should be mentioned which was principally scepticism of the knowledge of causal relationships. This was the subject of Kant's answer to Hume which is a unit of study in its own right.// — Wayfarer

:up: Interesting points. I am going to go over Kant's view on Scepticism too, after Hume. This post seems giving me insight and guidance where to look in Kant's sea of works. Thanks. I will read your post with attention, and will get back to you if I have any point to add, ask or criticise. :D

What do you want me to do, quote all the places where Hume is wrong? — Metaphysician Undercover

No, doesn't have to be all, but more the merrier of course. But this is good. It gives me good guidance where to look. I am grateful. Thanks.

Check this reading group: https://thephilosophyforum.com/discussion/13614/reading-group-humes-of-skepticism-with-regard-to-the-senses — Metaphysician Undercover

:up: :pray:

It is illogical to say "the World exists." Because pure reason cannot grasp totality of all appearance in the universe… — Corvus

Ehhhh, maybe. I’ll have to back check that. But there’s a more exact exposition of why not. See A592/B620 for the groundwork, if you’re so inclined.

Ehhhh, maybe. I’ll have to back check that. But there’s a more exact exposition of why not. See A592/B620 for the groundwork, if you’re so inclined. — Mww

Sure, I feel this is one of the interesting points in CPR. Will have read and thoughts, and get back for further discussions and clarifications.

He goes on proving Philosopher's belief in the existence of the external world, and concludes that the belief cannot be based on reason, but imagination.  There are extensive arguments and proofs why this is the case. — Corvus

Arguments do not prove anything; they are merely consistent (if valid) with their presupposed premises.
This means that belief in the existence or non-existence of the external world is based on reason, but the premises that reasoning, whether for or against, is based on cannot be certain and are themselves based on abductive speculation (imagination). None of which disagrees with Hume, so it looks to me like it is you who misunderstand Hume.

Rather that they are grounded in the human mind, so, if you like, a kind of 'universal subject' rather than an individual ego. — Wayfarer

Do you believe in the existence of a universal subject?

I will respond with an exposition of the transcendental nature of the Self from the Upaniṣads. While is true that there are many cultural divergences between Kantian and Indian philosophy, his notion of the transcendental subject of experience is plausibly comparable to the ātman of Vedanta.

Yājñavalkya says: "You tell me that I have to point out the Self as if it is a cow or a horse. Not possible! It is not an object like a horse or a cow. I cannot say, 'here is the ātman; here is the Self'. It is not possible because you cannot see the seer of seeing. The seer can see that which is other than the Seer, or the act of seeing. An object outside the seer can be beheld by the seer. How can the seer see himself? How is it possible? You cannot see the seer of seeing. You cannot hear the hearer of hearing. You cannot think the Thinker of thinking. You cannot understand the Understander of understanding. That is the ātman."

Nobody can know the ātman inasmuch as the ātman is the Knower of all things. So, no question regarding the ātman can be put, such as "What is the ātman?' 'Show it to me', etc. You cannot show the ātman because the Shower is the ātman; the Experiencer is the ātman; the Seer is the ātman; the Functioner in every respect through the senses or the mind or the intellect is the ātman. As the basic Residue of Reality in every individual is the ātman, how can we go behind It and say, 'This is the ātman?' Therefore, the question is impertinent and inadmissible. The reason is clear. It is the Self. It is not an object.

"Everything other than the ātman is stupid; it is useless; it is good for nothing; it has no value; it is lifeless. Everything assumes a meaning because of the operation of this ātman in everything. Minus that, nothing has any sense.

Then Uṣasta Cākrāyana, the questioner kept quiet. He understood the point and did not speak further. — Brihadaranyaka Upaniṣad

Arguments do not prove anything; they are merely consistent (if valid) with their presupposed premises.
This means that belief in the existence or non-existence of the external world is based on reason, but the premises that reasoning, whether for or against, is based on cannot be certain and are themselves based on abductive speculation (imagination). None of which disagrees with Hume, so it looks to me like it is you who misunderstand Hume. — Janus

Your post sounds like as if you have not read anything on Hume and any messages in this thread with attention.  What does Hume say about  the way our beliefs arise for the continuous existence of the external world?

Your post sounds like as if you have not read anything on Hume and any messages in this thread with attention.  What does Hume say about  the way our beliefs arise for the continuous existence of the external world? — Corvus

Our belief in the external world and causation are habitual based on the experienced reliable presence of objects and invariance of objects and the observed constant conjunction of events.

What do you think he says?

Our belief in the external world and causation are habitual based on the experienced reliable presence of objects and invariance of objects and the observed constant conjunction of events.

What do you think he says? — Janus

You have not even understood the question. The question was not about the external world, but was about the CONTINUAL existence of the external world (when not perceived).

They are the same question; if the existence of the world depended on your perception of it, it would not be at all external to perception.

If we have no reason to believe in an external unperceived world then we have no reason to believe in an external perceived world.

And you haven't told me what you think Hume says about it. If you are unable to present his arguments in your own words you could try quoting him directly.

Can I ask if it would make any sense to believe otherwise? Then if it matters at all if we believe in such an ‘existence’ extraneous to our general sensory interaction as part-of the world (rather than as some disembodied entity).

You might be interested in Descartes proof of the outside world, from the MM:

I will conclude that, if the objective reality of any of my ideas is such that I clearly recognize that it is neither formally nor eminently in me and that, consequently, I cannot myself be the cause of it, it necessarily follows that I do not exist alone in the world, but that there is still something that exists and that is the cause of this idea; whereas, if such an idea is not found in me, I will have no argument that can convince me and assure me of the existence of anything other than myself; for I have searched them all carefully and have not, until now, found any.

The issue then is that the proof is only a tool to prove God. He does not see in the outside world anything that he himself could not have generated. The only idea that must come from an outside source is his/our idea of God:

Now between these ideas, apart from the one which represents me to myself, from which there can be no difficulty here, there there is another which represents to me a God, others corporeal and inanimate things, others angels, others animals, and finally others which represent men similar to me. But as for the ideas which represent other men to me, or animals, or angels, I easily understand that they can be formed by mixing and composing other ideas that I have of bodily things and of God, although besides me there were no other men in the world, neither any animals nor any angels. And as far as the ideas of corporeal things are concerned, I do not recognize nothing so great or so excellent, which does not seems like it could come from myself

Later on the sixth meditation, we see the simple argument that if there were something in my mind causing the perception of the, materially false, outside world, I would be aware of it. Not being aware of it, it must be the case that it comes from outside. However in earlier meditation he speaks about a possibly unknown part of the mind:

“Can it, however, also happen that these same things which I suppose not to be because they are unknown to me, are not actually different from me, who I know?”

and

“[…] more distinctly known than that part of myself which I do not know and which does not affect the imagination;”

Though these possible unknown parts of his nature would not affect the imagination, he claims. There is no reason prima facie that some unknown part of the mind would not affect it, but defining the mind as at least things that I am conscious of, it can't be the case. As SEP puts it:

For from the additional premise that nothing can be in my mind of which I am unaware, it follows that if sensations were being produced by some activity in my mind, I’d be aware of that activity on the occasion of its operation. Since I’m not thus aware, it follows that the sensation I’m having is produced by a cause external to my mind. — Stanford Encyclopedia of Philosophy

That alone proves the outside world, be it things or an evil or good god. When it comes to a physical world, Descartes' approach is not without trouble, as is explained in the following SEP article.
The article “Descartes’ Theory of Ideas and the Existence of the Physical World” by Şahabeddin Yalçin might be useful. Also SEP's article on that part of Cartesian philosophy.

Can I ask if it would make any sense to believe otherwise? Then if it matters at all if we believe in such an ‘existence’ extraneous to our general sensory interaction as part-of the world (rather than as some disembodied entity). — I like sushi

The belief in the existence of the hypothetical planet Vulcun comes to mind. Sometimes even the Scientist believe in the non-existence of the contiguous external objects when not perceived.

You might be interested in Descartes proof of the outside world, from the MM:

I will conclude that, if the objective reality of any of my ideas is such that I clearly recognize that it is neither formally nor eminently in me and that, consequently, I cannot myself be the cause of it, it necessarily follows that I do not exist alone in the world, but that there is still something that exists and that is the cause of this idea; whereas, if such an idea is not found in me, I will have no argument that can convince me and assure me of the existence of anything other than myself; for I have searched them all carefully and have not, until now, found any. — Lionino

Good point. :up: Thank you for your post, and welcome to TPF.

So we are now talking about the ‘existence’ of fictional and hypothetical worlds?

No thanks. I am out.

Only so many liberties we can take with words before gibberish takes over.

So we are now talking about the ‘existence’ of fictional and hypothetical worlds?

No thanks. I am out.

Only so many liberties we can take with words before gibberish takes over. — I like sushi

No, it is about how our mind and belief works, and how even Science use our belief in non-existing existence and observations as a methodology at times for finding and exploring the universe.

Your rushed and senseless judgement on the point seems to be based on misunderstanding and ignorance on the topic. All the best.

I have edited and updated my answer on the Cartesian proof to be more complete.

I have edited and updated my answer on the Cartesian proof to be more complete. — Lionino

Thank you. :cool: :pray:

Ehhhh, maybe. I’ll have to back check that. But there’s a more exact exposition of why not. See A592/B620 for the groundwork, if you’re so inclined. — Mww

I was reading B446/A420 and B448/A421 in CPR for the part, where Kant says that the World is totality of all appearances in the universe, therefore it is beyond the grasp of Reason. The topic of the World is, therefore subject of Cosmology.