There is no illusion indistinguishable from reality. — BrianW

Then I defer to your omniscience. For myself, I cannot scale such heights. I seek logic that works for me, with all my faults and deficiencies.

BIV is a truth... — TheWillowOfDarkness

No, it's not. It's a speculation. How could we recognise it as 'a truth', when there is no evidence concerning its correctness?

There is no point to a position which leaves us without any sort of knowledge. It's just a waste of our time. — TheWillowOfDarkness

How about the knowledge that we have no knowledge pertinent to the matter in hand? To move something from 'don't know we don't know' to 'know that we don't know' is worthwhile, isn't it? :chin:

...Another difference between reality and illusion is the multifaceted/versatile nature of reality in contrast to the one-sided nature of illusions.... — BrianW

You consider only illusions that are detectable because they feature imperfections? Of course such illusions can be detected, with application and practice. But can you not conceive of a convincing illusion? One good enough to convince you (and me), at least? That is what we are discussing here, surely?

If it's indistinguishable, then it is the same — TheWillowOfDarkness

So, if you were colour-blind, red and green would become 'the same', because you can't distinguish between them? The two speculations are indistinguishable to us humans.

BIV claims direct access to objective reality — TheWillowOfDarkness

Not really. It offers a possible speculation, nothing more. RL is another such speculation. If we were concerned here with their correctness, we would truly be wasting our time, for such speculations cannot be verified or falsified. But we are, instead, wondering how these speculations, and others like them, should be dealt with logically. Thankfully, this does not require access to OR. :wink: :up:

We already know by our experiential lives we are not BIV. The events of my life, my experiences, my body, the interactions I have with other and everything around me, etc., these are not a Brain in a Vat-- I mean, my brain is in my skull. — TheWillowOfDarkness

You can't know that, which is rather the point. The BIV speculation is defined to be indistinguishable from the RL speculation, and from every other possible speculation concerning our relationship with Objective Reality. BIV and RL are indistinguishable to us. Either could be correct, or both could be wrong. But we do not and cannot know that we are, or are not, BIV.

If we are having "theories" some sort of context of evidence is proposed. We are posing some sort of event or phenomena and then developing description which reflects it. These cannot be outside evidence because they are evidential claims. — TheWillowOfDarkness

Then what is the BIV speculation? Because it concerns our relationship with Objective Reality, something to which we have no direct (Objective) access, we don't and can't know if it's correct (or incorrect). And there is no evidence. There are other such issues; BIV is only an example. The RL speculation posted earlier is another one. There is no evidence for its correctness either. So what do we do with such speculations? I cannot accept that we should dismiss them because they're difficult to deal with. If there are good reasons to dismiss these things, I would like to know what they are. One thing I think we can all agree is that our reasoning would be simpler and clearer if we had such reasons.

Reality is (for us humans) filled with uncertainty. Everywhere we look, there are things we don't know, and some of them we can't know. At least knowing that we don't know is a step in the right direction, n'est ce pas? :smile:

I apologise for getting involved in this distraction. I should know better at my age. :blush:

If you know how to deal logically with speculations that come without evidence, please say so.

A deduction is a species of inference — StreetlightX

A deduction follows directly and unavoidably from its source material. Inference generalises from the specific, and is unreliable for that reason. Deduction is not inference; it is as reliable as the source on which it is based.

Why do speculations not need to be disproven? — Pattern-chaser


Because rationality deals with arguments on the basis of the inferences that are soundly and validly developed in the course of those arguments. — StreetlightX

But when there is no evidence, there can be no inferences. This topic asks what we do in such circumstances, not what we (should) do in other situations. And besides, inference is unreliable. I prefer deductions, or a simple admission that 'I don't know'.

Stephen Hawking was afflicted later in life, but he is an illustration nevertheless of how misleading the term "disabled" can be. — Baden


Yes, of course you're right. Stephen Hawking should've been drowned at birth, right? :fear: Because he was just a "parasitic drain" on society, right? :fear: Yeah, kill 'em all! :fear: :groan: :cry: :rage: — Pattern-chaser — intrapersona

By placing these quotes after one another, you make it look like I was responding to @Baden, when my post clearly quoted you. You really should be more careful.

Yes, of course. A real illusion is, of course, real. — Pattern-chaser


I'm not saying illusions are real. Only that the components of illusion are borrowed from our perception of reality. — BrianW

I am (saying illusions are real). They aren't what they pretend to be, of course, that's what illusions are all about. :wink: But an illusion has existence as such, so it's real. :up:

As to BIV and RL, I would ask that you formulate a personal test for which to recognize the difference between reality and illusion. A kind of litmus test for the difference between the 'texture' of illusion vs that of reality. I believe you will find it impossible to mistake one for the other. — BrianW

Issues such as we are discussing here wouldn't even exist if we (humans) knew of a test by "which to recognize the difference between reality and illusion". It's the nub of the problem. In many circumstances, we can't distinguish reality and illusion (or even hallucination).

I would love to create a test such as you describe, but I'm afraid I can't. :meh: I have no clue as to how to go about it. :fear: I actually believe it to be impossible, but I'm very much open to persuasion. So please, go ahead and explain how, for example, we can detect the "texture" of an illusion. It would be really useful. So can you help? Go on, try it. "I believe you will find it impossible to" distinguish one from "the other." Prove me wrong. Please. It would be enormously helpful and useful.

[Some illusions are poor illusions, and seeing through them is easy for anyone. Can we please assume the illusions we're considering are convincing illusions, OK? It simplifies the discussion. Great. Thanks. :wink: ]

Indeed he was. :up:

Which in the case of disabled people isn't much at all really is it? Are they not like a parasitic drain due to our ethical hesitation? — intrapersona

Yes, of course you're right. Stephen Hawking should've been drowned at birth, right? :fear: Because he was just a "parasitic drain" on society, right? :fear: Yeah, kill 'em all! :fear: :groan: :cry: :rage:

Lifelong suffering from disability can be prevented yet you want to argue we ought not to intervene with our superior intellects (much in the same way judges do)... — intrapersona

This kind of thinking leads to mentions of things we're supposed to avoid on the internet. So I'll confine myself to shuddering with fright when I wonder which intellects are sufficiently "superior" to decide whether my own disability condemns me to euthanasia? Do you consider yourself up to this task? :chin: I'm afraid I don't. Sorry. :fear:

just stories for children playing at philosophy — StreetlightX

A lovely image. :up: Stories are how humans learn and remember best. You can deal with reality as you see fit. I will continue to think about things I consider interesting, and the stories presented here are interesting, to me at least. It seems one or two other people also agree. Perhaps you should just leave us kids to play here, in the philosophy playground? :razz:

Speculations do not need to be disproven — StreetlightX

Another unjustified assertion. Why do speculations not need to be disproven? What is the logical justification? You keep insisting that there is no question to answer, but all you offer to support your case is unjustified assertions. You seem to be presenting a position that you believe to be logical, and I'm asking you for the logical justification for your position. What is it?

I wonder if considering disabled people as a separate group in society is helpful? I find myself wondering if we should not be considering instead how each member of society (able or disabled) can contribute to society? Maybe we should look at the (in)efficiency of not "allowing" disabled people the support they need to make their contributions? Stephen Hawking made a contribution. Others too, although they are less well-known. I am autistic, which is considered by many to be a disability. Do I have a place in society? I too made a contribution during my working life. If you live in the UK, you can't make a telephone call without using my work. But I'm 'disabled'. What is your point here? Must I be euthanised, or held in a secure institution? :chin:

What grounds do you offer that could be rationally engaged with? — StreetlightX

You offered several speculations. I have taken them in the way you intended, and not given them serious consideration. I'm sure you haven't either. But let's consider them logically.

If any speculation can be disproven, logic seems to recommend dismissal. Fair enough. But what if you come across a speculation that is possible, but can't be disproven? What then? There does not seem to be a logically-justifiable reason to dismiss it. :chin: Do you know of one?

Rationality is not your - or anyone's - play-thing. — StreetlightX

I beg to differ. Isn't this exactly why we're here, in this forum? :wink:

I think your question is worth answering directly. As a preliminary venture. Consider:

BIV Hypothesis (BIV): I have lived a normal life on earth for many years. Last week I was, without realizing it, removed from my body. My brain was placed in a vat of chemicals and hooked up to various electrodes which produce in me sensory experiences just like those I would have if I were still in the ordinary world. For example, I have sensory experiences as if I am in my apartment; as if I am in my office; as if I am eating by the lake. But really, I am never in any of the places my sensory experiences show me to be in. I am a brain-in-a-vat, and I have been for a week, but I never noticed it.

Real Life Hypothesis (RL): I am now in my apartment having sensory experiences of my apartment. In general, my sensory experiences as a fairly accurate guide to my present surroundings. I have never been en-vatted. — PossibleAaran

Thank you for this, @PossibleAaran! :smile: With two examples, we can make the whole thing a little more interesting. I start from the position that both BIV and RL are possible, and that they both come with the same amount of evidence: none at all. Here's an interesting question:

Can we compare the two?

Odd as it seems, no. :chin: Having no means to assign probabilities of correctness to either speculation, we have no means to compare them. We can say that they are not both correct, as they contradict one another. We can say that one or both of them could be incorrect. Logic allows no further justified conclusions, isn't that so? :chin:

Also, a treat for those concerned that unlikely speculations are given equal weight with more likely scenarios: we cannot logically justify saying that BIV and RL are equally likely. This is because we can't establish a numerical probability for either one. :up:

My (unjustified!) conclusion is that we should never dismiss these things, but instead we should use them as it suits our convenience. RL offers me utility, so I use it. BIV is a teaching-story that I find otherwise useless, so I don't use it. But it remains a possibility, and I continue to remember this as my reasoning progresses. I'm not leaving lies behind me, to confuse me later. Isn't this the only practical and honest way of proceeding?

As a general rule any unmotivated question of the form 'is there any reason to think that such-and-such is not the case' can be readily dismissed out of hand. It is the conspiracy theorist's question: "is there any reason to think the Queen is not a lizard?; "is there any reason to think we are not ruled by aliens?";these are not questions to be taken seriously. They are questions to be laughed at and ridiculed. — StreetlightX

[My highlighting.]

Well that's great news! :up: Now, if you could just offer a logical justification for dismissing such things...? Seriously, some of these things just look ridiculous, and we dismiss them without a second thought. But are we justified in doing so, or are we just hiding from the uncomfortable truth, that we have no logical justification at all for dismissing such things? Is it all just to avoid admitting to ourselves that there are things - many things - that we just don't know, and that we can never know? :chin: :razz:

In short, It falls to Occam's razor. — hypericin

You seem to have mistaken Occam's Razor for something authoritative. :chin: It's just a rule of thumb, a way of guessing when we can think of no better way to proceed with our reasoning.

Putnam's BIV was never about what Pattern-chaser's want it to be. Not even close. It's not an earlier version of the Simulation "theory", never was anywhere close to it, and you are doing a serious disservice to philosophy by spreading this misrepresentation. — Akanthinos

With all due respect to Mr Putnam, I just picked up ('stole', if you like) a speculation that I used for illustrative purposes only. I make no attempt to show that BIV is true or false. In fact, I believe that it cannot be demonstrated to be true or false. That's the issue that I'm trying to focus on.

Philosophy is about thinking, and thinking about thinking. Almost any subject can be considered philosophically - that is to say, using careful consideration and structured thought - and I see no reason why this particular topic should be different. A "serious disservice to philosophy"? No. A simple application of philosophy, to discuss something that is usually ignored. :chin:

So, how should we treat these speculations? As a critique of our own belief. You do not need to provide evidence to build a critique -- use the other person's evidence if you'd like. — Caldwell

What evidence? The point of this discussion is to ask how we deal with speculations for which there is no evidence. It seems that logic takes us so far, but no farther. And when we reach that point, we must stop. The temptation is to draw conclusions anyway, instead of having the courage to admit that we don't know, and that the only logically-justified conclusion we can draw is ... that we don't know. :chin:

Outside of metaphysics the brain-in-a-vat theory is not as striking. — BrianW

It was never my intention to promote a discussion of whether the brain-in-a-vat speculation is true or not. It's only here as a good example of speculation which are possible, but that come without evidence. And let's be clear: I am not proposing BIV as being true (or false). Please can we leave the correctness of BIV alone? :wink:

I choose to accept a theory which states that illusion is a part of reality — BrianW

Yes, of course. A real illusion is, of course, real. :up: :wink:

...I do not find it worthy of belief. — Dfpolis

Oh my! :scream: I was hoping to convince you, so that others who are also in awe of your status and prestige might follow your attention, and maybe read my posts. What will I do now? I am bereft.

So, please justify your claim. — Dfpolis

we don't have Objective access, so everything you say about "the world" is necessarily speculative, and will always be so. — Pattern-chaser

The justification is that we don't have Objective access to "the world". The uncertainty follows from that.

Of course we have access to our own world. — Dfpolis

Yes, but we don't have Objective access, so everything you say about "the world" is necessarily speculative, and will always be so. :chin:

It seems to me that possible worlds talk is unnecessary, circular and a source of possible confusion.

First, it is unnecessary. As we can have no epistic access to any world but our own, actual world, anything we can learn, we can learn from the real world. — Dfpolis

Right at the beginning, you include assumptions such as "actual world" and "real world". What are these worlds, and where is your justification for their "real" or "actual" existence? These assumptions are unjustified and unjustifiable. It seems possible that, as a result, your following arguments cannot deliver reliable conclusions, can they? :wink: :razz:

Your logic is irrefutable! I therefore joyfully accept your conclusion. :up:

We could probably prove God is a Panda using similar methods. — Baden

...then I think we should! Let's do it! :smile: :smile: :smile:

Does it really matter whether we call it a thought experiment, a theory, a hypothesis or a fairy story? — Pattern-chaser


It matters. — Caldwell

And also:

Yes, it does matter. It is the topic. There are some moves which are permissible against a theory and which have no purchase whatsoever on a thought experiment. For example, questioning the likelihood. — Akanthinos

OK, then I apologise to all for my imprecise use of words, and re-present the topic as: how should we deal, logically, with speculations that are possible, but that come without evidence?

N.B. Brain-in-a-vat is a good example, but it is only an example, and not the topic itself. We are entirely unconcerned here with whether the brain-in-a-vat speculation is true or not.

I’ve intentionally avoided this thread because it addresses a darn good, and very complex, question. Compliments to the chef. — javra

:blush: :smile:

The BIV scenario, as far as I can comprehend, is one asking how we can justify that we are not BIVs. Maybe this can be justified. My best go at it in a nutshell: The very idea of being a BIV is dependent on there being such a thing as real brains, wirings, and computers. Yet if we were BIVs, then all our empirical data would be bogus by entailment of so being BIVs. — javra

I think that, because the source of our 'data' from 'the world' is Objectively (hard definition :smile:) unknown and unknowable, I don't think you can oppose any speculation of this type by focussing on the source of the data. :chin:

But BIV is only an example, and the main issue here applies to all such speculations that are possible, but that come without evidence. How should we deal with such speculations, logically? :chin: :chin: :chin:

All the same, I’d like to read of other logical reasons for dismissing some philosophical conundrums but not others. — javra

Me too! :up:

The Brain in the Vat is that it doesn't actually explain anything new. It doesn't answer any questions. It just proposes a scenario which is theoretically consistent with any set of observations. — hypericin

Indeed. But this topic offers the brain-in-a-vat scenario as an example of a speculation that is possible, but comes without any evidence. And it asks: how should we deal with such speculations, logically? :chin: :chin: :chin:

I think the brain-in-a-vat example is a very intelligent thought experiment. However, it ignores the reality of our perception. While most of our perception relates to our senses directly, there is a level of perception which seems to be beyond them. I mean instances where we meet a person and we perceive them as compatible/incompatible or as having some kind of good/ill intentions, etc. Intuition and gut-feeling may not be right all the time or exactly scientific but the accuracy and the degree of dependability by the instinctive mechanism is quite telling. — BrianW

Yes, this is how I understand it. When we dismiss a notion as unrealistic, we're using our nonconscious minds in the same way that we make up our minds about new people we meet within seconds. As you say, it's an instinctive reaction, and it works very well in situations that are ill-defined, maybe with many disparate variables involved. But it isn't always right.

In this circumstance, I'm trying to set aside this non-conscious response, and look at what lies behind it. Is there any logically-justifiable justification for, in this case, dismissing the brain-in-a-vat notion? I don't think there is. I can't find one, which is why I started this topic: to see if I'm missing something that someone here knows about. Am I missing something, or is it the case that our dismissal of brain-in-a-vat is arbitrary, unjustified and unjustifiable? :chin:

My default position in the absence of evidence to the contrary is that it would require a slightly different brain to 'run' a female body than to 'run' a male one. — Pseudonym

Yes, and a male-oriented brain running a female body might explain gender dysphoria as something other than a delusion. :smile: :up:

If they exist you should be able to assert what they are. How can something biological exist but defy definition? — Pseudonym

I don't think these things defy definition. But I don't know enough about the biology involved even to hazard a guess. The fault is mine. I believe that human bodies are adapted to their sexual/gender differences because I can't see that one, er, configuration could adequately deal with both. Am I wrong? :chin:

Known to many of us here: HItchen's razor: "What can be asserted without evidence can be dismissed without evidence." — tim wood

Yes, I've seen this before, but it's just like Occam's Razor: a rule of thumb which has proved useful in the past, which we can choose to apply if there's no better way of proceeding. Neither of these razors has authority; they're just ways of guessing.

If we are choosing to turn a spotlight on such decisions, as we are here, the use of rules of thumb (guesses) doesn't seem appropriate or useful. They just help to mask our lack of justification for the decisions we make about these things. It is my intention here either to convince you that we make these decisions without justification, or to learn from you that there's something I've missed. Can you help? :chin: :up:

↪Pattern-chaser
Because it's not simple and not settled. — Moliere

It's not settled that there are differences in the brains/minds of males and females, associated with their biological differences? I think it is. I don't assert any specific difference, only that these differences exist, yes? And if they do, the possibility exists for the brain/mind to be 'misaligned' with the rest of the body, in the particular respect of this topic, yes? :chin: