An epistemological proof of the external world.
I'm planning on writing a paper soon about the relationship between epistemological solipsism and using it as an ad hoc proof that knowledge is possible. I'm looking for some feedback or how to shape these loose ends into something coherent.
A while back I come to the conclusion that for any solipsist inhabiting a 'world', that solipsist cannot doubt. One of the implications of such a hinge proposition is that if a man or woman were presented with Descartes Evil Demon, which prods the fictional Job or what have you to doubt, then the very process of doubting cannot be doubted itself implying that the doubting of the evil demon is proof that the person is not living in a hermetically sealed off world of their own (brain in vat)/(solipsism).
Therefore, if one can doubt when confronted with any skeptical argument, then that implies that knowledge is possible, and that we don't live in a solipsistic world.
Let me expand on this idea of epistemological solipsism. The world of the solipsist is one and the same with the self of the solipsist. What does this mean? It means that doubt cannot arise, because the world of the solipsist is full of certainty. To present this issue another way, epistemologically the solipsist is hermetically sealed off from anything beyond what constitutes their 'world'.
That's about the gist of it.
Main points:
Descartes Evil Demon causes an individual to doubt.
A solipsist can never doubt, and live in a world full of certainty.
Therefore, in the presence of doubt knowledge is possible.
Hence, the Evil Demon's prodding to doubt is proof that an external world exists.
A while back I come to the conclusion that for any solipsist inhabiting a 'world', that solipsist cannot doubt. One of the implications of such a hinge proposition is that if a man or woman were presented with Descartes Evil Demon, which prods the fictional Job or what have you to doubt, then the very process of doubting cannot be doubted itself implying that the doubting of the evil demon is proof that the person is not living in a hermetically sealed off world of their own (brain in vat)/(solipsism).
Therefore, if one can doubt when confronted with any skeptical argument, then that implies that knowledge is possible, and that we don't live in a solipsistic world.
Let me expand on this idea of epistemological solipsism. The world of the solipsist is one and the same with the self of the solipsist. What does this mean? It means that doubt cannot arise, because the world of the solipsist is full of certainty. To present this issue another way, epistemologically the solipsist is hermetically sealed off from anything beyond what constitutes their 'world'.
That's about the gist of it.
Main points:
Descartes Evil Demon causes an individual to doubt.
A solipsist can never doubt, and live in a world full of certainty.
Therefore, in the presence of doubt knowledge is possible.
Hence, the Evil Demon's prodding to doubt is proof that an external world exists.
Comments (73)
The "deceiver" does not cause the doubt but takes advantage of it. Doubt is the natural element of Reason. The idea that one is being mislead by appearances on purpose is not a promotion of the isolation of solipsism but points to the difficulty of thinking for oneself.
From that point of view, Descartes' answer may be too easy.
Then I suppose you can do away with the Evil Demon and simply treat doubt as the main issue here. I suppose I can rewrite the conclusion as follows:
A solipsist can never doubt, and live in a world full of certainty.
Therefore, in the presence of doubt knowledge is possible.
Hence, doubt is proof that an external world exists.
An epistemological proof of the external world.
Does that sound better?
That works for me.
But i have to confess that I never got the solipsism thing. In any of its iterations.
I am probably the wrong person to ask. I simply do not understand the idea.
Well, to be honest this idea originated from my studies of Wittgenstein's Tractatus, mostly. In that the limits of my world are the limits of my language. This equates in some idealist sense, the world with the solipsist in a pantheistic sense. What results from this is that epistemically, one can expand the limits of one's world when confronted with doubt, which is impossible for a solipsist. Hence, doubt, contra certainty, is what allows one to overcome one's limitations in the world.
Hope that made sense.
That does make sense.
I will have to mull upon it.
Why would that be impossible for the solipsist? I mean wouldn't just the same restriction apply to new experiences?
Because epistemically, the solipsist is one and the same with the 'world'... I don't think there's much confusion about that statement, or not?
I don't understand. The point I am making can be thought analogously to a dream where a person self is in play and experiences are synthetically conjured up, in a solipsistic world that is finite. Does that make any sense?
I disagree despite not being a solipsist.
I accept 1).
2) The question here is what is "knowledge". I assumed it to be something along the lines of "the improvement of certainty". However I don't see why this is evidently given without further assumptions. Lets say the Self investigates a certain part of itself to increase it's knowledge of that part. This partial improvement seems possible with your conception. However there is no guarantee that while increasing the certainty in one domain by amount x there isn't a loss in (an) other domain(s) that adds up to the amount x. This would obviously lead it to be a zero sum game overall and only a shifting of certainty of different parts. To prevent this you would have to assume something along the lines that there is a net gain over time. I don't see any basis for that.
However lets assume this to be the case to look at 3)
3) I don't see/understand how the external world enters into this at all. Lets say the Self increases knowledge there is no reason why a solipsist couldn't just call this an improvement of the knowledge of the Self by the Self (since everything in this view is part of the self). Therefore gaining knowledge/certainty does not necessarily refer to an increase of knowledge of an external world and can not prove the existence of an external world.
This can be illustrated if you imagine an incompetent god that by accident creates the universe. After this god investigates said universe and improves his/her knowledge of it. There is no reason to conclude from that, that there has to be something outside of that universe.
Btw I think the approach of Fichte is interesting. His basic question is why is the "illusion" so consistent and strongly present. The approach he takes is investigating fundamentaly necessary structures/properties of the self with this. However this is only vaguely related.
Btw2. My approach is the idea of change being a necessary condition for the self preceding it. The self experiencing change requires it to change itself. On this basis in my opinion one can view change as external factor that the self has to obied by. I am aware of the fact that a solipsist could state that the self is necessary for change like change is necessary for the self. However I view it as unequal pairing since at least in principle one can imagine change without a self but not a self without change. (Since there would be no possibility to have experiences without change.)
However I don't want to divert further from your actual point I just thought it might be interesting to you.
Yes, the world horizon or what Wittgenstein calls the limits of one's world is expanded by the process of doubting. Now, how can a solipsist doubt if they live in a 'world' where everything is the same as the self?
If everything is the self and the solipsist can have new experiences, then she has not experienced all of her self in which case she is never omniscient and so there would be room for doubt, no?
I don't think there are degrees of certainty. It's a binary situation here, or at least for the sake of this thread, epistemic closure is guaranteed for the solipsist. Since the solipsist is one and the same with the world, then there's nothing to doubt, yes?
Quoting CaZaNOx
Quoting CaZaNOx
Well, just take the most popular book in the world, being the Bible. (Keep in mind that God, literally is the ultimate solipsist). S/He/It created us in his own image. While is this sort of irrelevant, I suppose it can be an interested corollary to the topic.
I don't think that the solipsist can experience genuinely new experiences. The boundary between doubt and certainty is rather explicit for a solipsist, which I assume you don't agree with here?
I'm not sure what you mean by "genuinely new experiences". Anything you experience which you haven't experienced before is a new experience, isn't it? There is a sense in which everything you experience is a new experience, because everything that happens is unique and unrepeatable.
Can you explain what you mean by the boundary between doubt and certainty being "rather explicit for a solipsist"? I mean if the world was nothing but you, and you knew yourself exhaustively, there would be nothing but certainty, would there? Or do you think it would be possible, assuming that the world is nothing but you, that there could be any doubt at all, in that case, that the world is nothing but yourself?
Isn't that a metaphysical claim? I believe Wittgenstein addressed this issue of private experiences or some such in the Investigations with his Private Language Argument.
Yes, I'm glad we are on the same page finally...
Quoting Janus
What do you mean?
I was just leaving open the possibility that you might not agree with the first two sentences, but you said you are glad we are on the same page, so apparently you do agree with them. The problem then is that I am never certain what will happen next, so there is apparently not "nothing but certainty" in which case solipsism is already refuted by the possibility of (unpredictable) new experiences.
As an example the fact that I am speaking to you, and have no idea what you will say next refutes solipsism on this criterion, and I would also say this applies equally to the dream world as it does to the waking world.
I can counter this by providing the 'Will'. In a dream where one is cognizant that one is dreaming, everything that happens is dictated by a sense of 'willpower' of the subject imposed on the happenings of the dream (now fully realized as one and the same). I haven't come across a better analogy to think of that would reflect the sentiments of this line of reasoning/thread.
Yeah, pretty much.
Quoting Janus
About how every one of us goes about in life, I suppose.
Are there any unanswered questions in your mind about epistemic solipsism and how it can be countered by doubt leading to the conclusion that if a person can doubt then that "experience" is grounds for proving the existence of an external world?
This can be gotten around by defining solipsism a certain way. First of all, the self is just another experience. For the solipsist, all that exists is the experiences a solipsist has. There is no hidden self generating the experiences of a world.
In addition, doubt is just one more kind of experience. Also, the solipsist can doubt because they do have experiences of what appears to be an external world full of other people. Remember that solipsism is a philosophical position that only comes about through inquiry and taking skepticism to its logical conclusion. Nobody is a solipsist by default.
What solipsism is supposed to do is to provide a certain philosophical outlook based on only the experiences a solipsist has and nothing else. It's actually a response to radical skepticism. But just because the position is certain doesn't mean that the solipsist can't doubt the truth of solipsism. After-all, experience appears to be otherwise, and you have all these people in those experiences criticizing and mocking the position.
As for new knowledge, it's just another experience. The question is why is there a stream of experiences if nothing is causing them? There's no more answer to that than why anything exists.
I further don't see why there should be nothing to doubt or what you are appling this to.
The main thrust of my argument im 2) was that there are parts that you can have knowledge of. To me this seems indicated by your wording of 1).
I would put it this way either their is a single domain (the entire self) to which one ascribes could ascribe certainty or there is a multitude of domains to which certainty can be attributed to. This second notion could also include the entire self.
If we look at descartes cogito (ergo) sum (I think, (therefore) I am) one can see that certainty is ascribed to ones existance. In other words even if the self knows nothing else the self is certain of it's own existence. The key conclusion is that a self that is purley based on doubt can not doubt itself at it's core. This view simultainously asserts that there seem to be other domains, being part of the self, that can be doubted. So the self would have only uncertainties no matter what is in question exept it's own existence.
I would therefore basically refuse that because the solipist is one with the world there is nothing to doubt. It evaluates different aspects differently the "Existence" as such is not doubted however any ascribed property is.
I don't see how you address my criticism regarding 3).
I basically suggested the analogy with god because he as you pointed out he/she seems to be the ultimate solipsts. His having a certain knowledge of the world(or not) doesn't shows or lead to concludimg that there is somethimg outside. Do you agree?
True, but, imposing a stipulative definition on a generic one to make the logic fit is basically cheating. I use solipsism not stipulatively here...
Quoting Marchesk
The self is the only experience a solipsist can attest to being true. Again, there is no ordinary 'world' in the "world" of the solipsist.
Quoting Marchesk
Yes.
Quoting Marchesk
Arguably, yes, although that issue is addressed in the Uppinshads and Bhagavad Gita.
Quoting Marchesk
Not true. Doubt is the only experience that is genuine here. Everything else in a solipsistic 'world' are what Wittgenstein might call tautologies.
Quoting Marchesk
Then, that wouldn't make them solipsists.
Quoting Marchesk
Not only that; but, solipsism is an extreme form of idealism. And, I contest here, just for the sake of argument, that the entity we call 'God' is de facto the only true solipsist.
Quoting Marchesk
Not the same kind-of experience as that of living in a solipsistic world...
OK, before we agree, I wanted to raise the issue of 'domains' with @Janus but, was too busy trying to reach some common ground...
The point with domains, is that the experience of the domain or 'world' of the solipsist is truth apt from within the world, and not by analysis wrt. to other domains. To try and phrase this abstract issue another way, if I and you spoke different languages, then we could only reach a common understanding through the use of ostensive definitions, which we could point at and say that 'grue' is the same thing as my 'water' while pointing at a glass or pouch full of water.
What am I getting at here? Well, the point in my mind is that domains that are non-truth apt (a common criterion cannot be achieved), such as the stuff that Wittgenstein talked about private pains or private languages, are non-nonsensical within language and must be shown. Perhaps @Banno can help out here.
And, this is why solipsism was/is (at least in my mind) thought of as a valid idea that one can hold, what cannot be doubted is the fact that one is doubting, within the domain of the self.
A solipsist cannot doubt because they are trapped in their own world. Epistemically closed off, hermetically sealed, thus doubt cannot arise because it is the opposite of what a solipsist experiences, supreme certainty.
Quoting Wallows
I first want to emphasize the word expierience (1) to refere to it later in my reply.
I agree that the world is not truth apt wrt. other (external) domains. This would just be misunderstanding the solipsistic viewpoint. It rather has to be as you state that it is truth apt from within.
However what seems to me especially problematic is Quoting Wallows
Lets ignore the language the other speaks and focus, from the solipsitc perspective, on the notion of there being a language at all. The key point of an (internal) language is that it names different things differently in order to conceptualize the world from within. This however needs as precondition different things/domains that are worth distinguishing from within. This analogy seems completley missplaced if one understands the solipsistic perspective to only contain one domain (the self/world of the solipsist).
Now I see no reason why a solipsist couldn't in general state that existence necessarily is given despite there being doubt because of him experiencing at all. However negate any content of his experience/statement formulated by his internal language and therefore it's validity. This could also be applied to doubt that can be understood as reasoning with/applying the internal language, that can be faulty. Therefore in principle doubting itself as process could be entirely misguided in framing the doubt. Further any attempt to state what one is doing could be misguided, including doubting itself. I obviously agree that from an outside perspective one could form that statement but not from within.
I want to point this out by referring back to experience(1).
I wrote Quoting CaZaNOx
The key points for entering the brackets is that with the brackets we are applying a coherent language with coherent logical conclusions. This is not the case for the solipsist at all. For him it is somehow a experience in which he by thinking/doing sth.(whatever this is) he experiences sth. Where the experience contains the manifestation of existence of the self at a fundamental level. However in form of experience there doesn't have to be any proper realization of this as we framed it with our coherent use of language from the outside. As you surely know at this point of his work descartes already negated the conceptualizing a triangle as thing with three angles. The solipsist so to speak seems to be in an phenomenological hole where all he has is incoherent experiences. (I don't know how clear I made this point?)
However what I completely fail to grasp is why and how any of this things should refer at all to the existence of an outside world at all. Even if we assume the solipsist to be at a way better place then the self that is doubting in descartes meditations f.e. based on an approach similar to Fichte that based on experiencing consistency infers consistency that has to be explained by a certain necessary internal structure, allowing somewhat proper internal language.
This I think as you would agree leads to an axiomatic system where there is no doubt and only deductive proofs that are certain in said system. However the certainty of the axiomatic system itself build by the self is not free of doubt. Because the chosen axioms by the self are open to doubt as descartes showed. There is no reason why different solipsitic positions couldn't build different axiomatic systems or why a self couldn't swap between them if they build this system at all.
In terms of language, because the language is so to say only internal the meaning of the words would be certain. However this doesn't exclude the possibility of inventing a new language from scratch.
A solipsistic position could for example include the necessary experience of doubt. We could even translate this to conceptualizing death(as we understand it) to mean in solipsism an expierience of doubt that leads to a complete new language/axiomatic system after death. This obviously would have to be reasoned by the current language logic used by the solipsist. However I really want to emphasize again my overarching core question. Where is the pointer to an external world in this at all?
Sorry that I can't address the entirety of your post, given my limitations here.
The point with the domains analogy was that the solipsist can only doubt if and only if there is something more than the self of the solipsist in existence. Hypothetically, we can assert that the solipsist lives in a world that only is immediately knowable to the solipsist and not other.
Thus, my post about domains of discourse and the like. Let me know if that helps.
Why can he just assume incoherence of his reasoning process or axioms or words used.
Or why can't we conceptualize the solipsist simply as having expieriences of incoherence.
In other words don't you need specific assumptions to justify your iff.
You seem to say that doubt necessitates external initators, however the loosing of consistency or coherence can be thought of as internal initators of doubt that can in principle be build into the self. In the analogy of death I used above: death as internal shortcoming/necessary-process/change from within without conceptualizing external factors that lead to death (this case gets clearer if a solipsistic position doesn't necessarily postulate a material body that could be subject to external forces.)
Quoting CaZaNOx
Yes, you're on point here. These conditions are multifaceted in the Tractatus. Spinoza's pantheism and necessitarianism, Schopenhauer's theoretical egotism, Kant's Transcendental Idealism all contribute to the conditions allowing Wittgenstein to postulate such an entity as novel and unheard of until its publication. Mind you, even in his Investigations I don't believe he repudiated the notion of a hypothetical solipsist. This line of thought continues into his latter philosophy presented in On Certainty.
Here is P.M.S Hacker on this solipsism present in the Tractatus:
What the solipsist means, and is correct in thinking, is that the world and life are one, that man is the microcosm, that I am my world. These equations... express a doctrine which I shall call Transcendental Solipsism. They involve a belief in the transcendental ideality of time. ... Wittgenstein thought that his transcendental idealist doctrines, though profoundly important, are literally inexpressible.
— Hacker, Insight and Illusion, op cit., n. 3, pp. 99-100.
1) A solipsist lives in a world full of certainty.
2) Epistemologically, Cogito ergo Sum, ergo, a solipsist self is one and the same with the world, leaving no room for doubt in such a world.
3) A solipsist cannot doubt and live in a world full of certainty.
4) Where doubt arises, the world is not solipsistic.
5) Therefore doubt presupposes a world where epistemologically one can find out new facts or experiences about the world.
6) Hence, where doubt arises, the existence of an external world that is non-solipsistic is warranted to assume and/or conclude.
I don't see how that follows. If your belief that the external material world existed was false then you wouldn't be able to have doubts and knowledge would be impossible?
Well, the ability to learn more, establish norms, and do all sorts of things would be moot for a solipsistic being that lives in a world full of certainty. Yes?
I don't see how this is a response to my objection.
It could not be proven false in the same way the set of all sets cannot contain itself. Or another way to frame the issue is if you were born in a coma and lived in a dreamless world, since dreams attain their ontological significance from the waking world.
In order to know something you have to know that the contrary is impossible.
How could you justifiy your belief in the external material world without begging the question?
Well, yes just as the fact that I am doubting cannot be proven false or analogously the cogito ergo sum entails that existence is a prerequisite for the statement to even be plausible. Conversely what would the contrapositive even mean in that case?
Quoting GodlessGirl
I think I laid out my thoughts about this with the above.
Quoting GodlessGirl
I'm not quite on the same page, can you elaborate, please?
You seem to be strawmanning me. I am not proposing a contrapositive for your belief that you exist and doubt. I am saying you do not have justification that the external material world exists. There is no observation that is inconsistent with Descarte's demon being the case.
Therefore solipsism or a brain in vat? No, I already expanded on the fact that doubt epistemically presupposes that one is not a solipsist, and hence the external world exists.
I'm convinced it does. Here it is again in standard form:
A solipsist is one and the same with his or her own world.
Epistemically the solipsist lives in absolute certainty.
A solipsist cannot doubt and live in absolute certainty at the same time.
Therefore, where doubt arises, there is more to the world of a solipsist than only their self in it.
It could be said that there is more to the self that one's knowledge of the self at a particular time.
As an analogy, if you consider that a lucid dream stems from a self, then there are things you can doubt within a lucid dream, but that doesn't imply in itself that the lucid dream stems from something outside the self. Then continuing with that analogy, to a solipsist everything is a lucid dream, so doubt doesn't imply something outside the self, but only that the self doesn't know itself completely.
We don't have to assume that the self would have to know everything about itself. Then it's a matter of interpretation whether we see the unknown as something separate from the self or as an unexplored part of the self.
A limitation in this kind of discussion is that our language and concepts stem from what we experience, so for instance the very concept of doubt stems from our experiences, and then if you assume that doubt cannot exist if there is only a self then you conclude that there is something separate from the self, but if you assume that doubt is a normal part of the self then it doesn't follow that there is something separate from it.
Yes, and that is an issue worth exploring. The self as we know it in today's Western pop-psy lingo is composed of an ego-ID-and super-ego. I have a very small ego, infinitesimally haha. The continentals have exalted the ego to the point of arriving at postmodernism and the like. Yeah, a lot can be said here.
Quoting leo
Well, you might be taking the analogy too far. I suppose the point is that in a word where only the self exists, there is absolute certainty. Perhaps the ID is Satan, the ego Jesus, and the super-ego God?
Quoting leo
Yes, go on, what do you mean by something separate from the self?
Something that is not the self. If there is only self then there is nothing that is not self, nothing separate from it, nothing independent of it, nothing outside it. If there is only self everything is part of it, everything is connected.
If there are two parts of the self that seem always disconnected, then we could say that the self has not managed to see the connection, or we could say that there is something besides the self.
We could see all of us as part of one self, seemingly disconnected, but connected in a way we have not quite uncovered yet.
Sorry, I totally missed your post...
The difference between the matrix and a solipsist is in that the matrix still engendered the idea of separate selves in the simulation. Which, is fundamentally different than the world view of the solipsist.
Yeah, this is pretty much the starting point for any form of spiritualism. Yet, the solipsist is a fictional God if you can extrapolate from what I've been preaching.
We might be talking past each other with solipsism. I just mean the position that you can never know if any other minds or a material world exist. I dont see an argument for being able to know Descartes demon doesn't exist.
Yet another "Huh?" response from me. A lot of what you wrote seems bewildering to me.
The first question, I suppose, is why are you conflating solipsism and whether knowledge is possible? They're not the same thing.
I don't know if you're being facetious or not. The self of course exists, otherwise who's talking here?
A solipsist is one and the same with his or her own world.
Epistemically the solipsist lives in absolute certainty.
A solipsist cannot doubt and live in absolute certainty at the same time.
Therefore, where doubt arises, there is more to the world of a solipsist than only their self in it.
Quoting Terrapin Station
I'm using solipsism as a template to compare an entity to that which a fictional entity might assume to have knowledge about in an absolute manner. Given that a solipsist is tantamount to being a godlike entity, I then proceed to show that their omniscience of the world they inhabit, corresponds with a degree of knowledge that leave no room for doubt. Thus, where doubt is not possible, then that solipsistic world excludes the existence of other minds, or an outer world apart from one's own self. Therefore, where doubt is possible, then that would validate, through contradiction of the previous, the idea that there exist other minds or an external world.
That's not a tenet of solipsism and it doesn't follow from anything. Consider thoughts you have, things you imagine, ways you feel, etc. Aren't they sometimes vague/uncertain for you?
It follows from assuming from assuming that everything that there is to know is contained within the world. And, if the solipsist self is one and the same with the world, then s/he knows everything there is to know about the world.
Maybe it may be easier to assume that God is a solipsist, also?
You completely ignored this part: "Consider thoughts you have, things you imagine, ways you feel, etc. Aren't they sometimes vague/uncertain for you?"
Well, yes, there's the issue of hidden processes of the mind that are unknown to the conscious mind, such as intentions, the very existence of dream characters (a really interesting question, as to how do dream persona have their own intent), and feelings.
But, this seems to not detract from the gist of the solipsist being tantamount to a fictional god-like entity. I mean, aren't you in control of all aspects of your dream-world, when you dream?
I'm not talking about things that are hidden or unknown/not conscious.
Are you telling me that all of your conscious thoughts, imaginings, feelings, etc. are certain for you and never vague, fuzzy, etc.?
Then please specify, what's the problem in my analysis of claiming that a solipsist (such as a God) is epistemically omniscient?
[quote=Wikipedia]Solipsism (/?s?l?ps?z?m/ (listen); from Latin solus, meaning 'alone', and ipse, meaning 'self')[1] is the philosophical idea that only one's mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside the mind. As a metaphysical position, solipsism goes further to the conclusion that the world and other minds do not exist. This extreme position is claimed to be irrefutable, as the solipsist believes themselves to be the only true authority, all others being creations of their own mind.[/quote]
As you can see the solipsist view stems from doubt that the question "do other minds exist?" clearly demonstrates. I don't see how that questioning mind, the doubt that bothers the solipsist, leads to certainty as you put it.
Imagine if you were a true solipsist, or "God", does God doubt? Wouldn't an omniscient being not even be able to doubt?
How's omniscience related to solipsism?
From what I can see solipsism is born from not knowing rather than knowing. You may be referring to hardline solipsism here but I don't subscribe to the belief that only I exist.
Yeah, well think about it this way. I am omniscient, there is nothing more to know about the "world". Hence, the life of a solipsist is epistemically absolute, no doubt can arise.
Quoting TheMadFool
Pretty much hardline solipsism.
But it's not necessary for there to be no other minds. An omniscient being may come to know other minds exist.
That may be true, but doesn't detract from God ever truthfully answering a question with:
1) It is possible for an omniscient being to know other minds exist. So omniscience doesn't lead to solipsism.
2) Solipsism arises from doubt and so solipsism doesn't entail certainty.
As for an external reality let's try proving that proving whether it exists or not is impossible or possible. I'll try proving that it's impossible for us to know anything about the existence or nonexistence of an external reality.
Our senses can be likened to TV screens through which we perceive reality and we're like people trapped in our TV rooms with no doors or windows. Our only access to the world is the TV. How can we ever know that the TV is giving the right information or not? So, it seems that solipsism actually refutes your claim and although it's impossible to deny an external reality we can "certainly" put such a notion in doubt.
Not really. Think about a dream world which you inhabit during sleep. You see other people in it who seemingly have an intent of their own. But, the reality of the solipsistic dream world is one where you are the only mind present in it, and your-self is the only mind creating these dream characters with "other minds". Hope that makes sense. It's important that I highlight here that the solipsist's self is one and the same with the "world". There is nothing beyond this solipsistic world, epistemologically.