I heard someone make an assertion that 'We cannot really prove that there is reality.'.

'Reality' here would mean the universe and everything in it. You could look at an apple and think its an apple but it could really be something else, and we cannot really prove its "appleness".

My initial answer was the mere fact that having a notion for reality is proof enough that there is such a thing.

My question is: Is that a sufficient answer? Is there a proof that reality exists? Or is the question a valid one to begin with?

  • Do you mean, in reality it is no apple? Then there is a reality: One where there is really a football you are looking at or one, where you are only imagining an apple when in fact you are really staring at thin air. So are you asking if our senses could be systematically deceived and we don't see, what there actually is? Or are you asking if there is something "out there" that could be perceived (be it an accurate perception or not)? – Einer Sep 11 '14 at 19:28
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    Invisible apples?! So sorry, couldn't resist. – AndrewC Sep 11 '14 at 19:53
  • I don't think your initial answer is a sufficient one for surely there are things you (or some SciFi author, say) can now think of that have no known representation in reality. – Drux Sep 11 '14 at 20:42
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    A logical positivist would say that empirical matters can never be absolutely verified while tautological matters (a.priori truths like 2+2=4) are always absolutely true whether they exist in reality or not. But just because it can't be proven does not mean the sun will or won't rise tomorrow. It means we can only ever be 99.9% sure the sun will rise in the morning. Omg I hope it rises. – DrewT Sep 13 '14 at 20:16
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    Would the prove be part of reality? – Drux Sep 26 '14 at 15:19

19 Answers 19


We cannot really prove that there is reality

What would it mean to prove reality? Simone Weil, philosopher and younger sister to the famous mathematician Andre Weil (who solved the local Riemann hypothesis) wrote in her Lectures on Philosophy - which are in fact notes compiled by one of her students:

One can never really give a proof of the reality of anything; reality is not something open to proof, it is something established. It is established just because proof is not enough. It is this characteristic of language, at once indispensable and inadequate, which shows the reality of the external world. Most people hardly ever realize this, because it is rare that the very same man thinks and puts his thought into action ...

The right question to ask is how can we justify our knowledge of the world; this brings us to epistemology: where the notions of inate ideas, inference, deduction, analogy and authority are explicated.

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    If I understand the author correctly, it seems that she is confusing two very different questions here: that there is some reality that we can realize and whether we can be sure about the full reality of something (i.e. essence). As I also explained in my answer, there can be no doubt that there are some realities but our perceptions of reality can be (and indeed is) open to revision and correction. However at each instant there can be no doubt that there are some realities realized by a supreme indisputable reality: our self-consciousness. – infatuated Sep 12 '14 at 3:13
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    @infatuated: She isn't questioning reality per se; but how one proves it; I'm supposing that the OP use of the word 'proof' is orientated towards mathematics or formal logic given the demographics of this site; Descarte, for example takes it as an axiom that 'he thinks'; because as you say there is 'no doubt' of that. Having said this in Buddhist philosophy there is a standard position that disputes the reality of the unitary self - its essence as such. – Mozibur Ullah Sep 12 '14 at 3:29
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    Having said that its not a position I go along with - though I find it intriguing; for Weil, to establish rather than prove that 'you are' is to have self-awareness. To establish the reality of an 'apple' one merely needs to perceive it; however to establish the reality of an 'atom' this must be inferred - through science - we do not have direct awareness of that ontological level of reality. – Mozibur Ullah Sep 12 '14 at 3:33
  • Am I right that by 'proof' you are talking about logical proof as in inference, whereas in 'establishing' you're referring to acts of observation (of both one's self and the external world)? I'm not sure if I understand Weil's distinction between 'proof' and 'establishing'. – infatuated Sep 12 '14 at 3:56
  • As for the Buddhist theory, there are similar thoughts about elusive/illusive nature of the universe in Islamic sufi/philosophical thoughts. However they do not reject the relative reality of the universe and one's self but how they are misunderstood in relation to greater more substantial realities that underpin them. – infatuated Sep 12 '14 at 4:05

I think one reality is certain and indisputable: our own individual reality which is intuitively perceived without the need to any empirical data or substantiation. There can be no doubt that you are a self-conscious reality: a reality that realizes itself!

Now on the analytical level, the statement "there is no reality" is itself an expression of a reality (the reality of no reality) and therefore a self-defeating statement, nevertheless it proves that we humans have a general sense of 'reality' (that there is something after all that is 'real'). This sense is rooted in our self-conscious being that, as I discussed earlier, is one indisputable supreme reality, if you will.

But as for the reality of things that exist out there, we have no way but to employ our natural and artificial means of perception and observation to examine their reality. If our perception or scientific study of an external reality informs us that "there is an apple out there" and there's no other way to prove it otherwise, there seems to be no rational reason in assuming that the observed reality is something else. There's no question that all observed phenomena can be open to scientific reexamination and revision, but in absence of new information about the reality, as I said, there's no reason (as there's simply no evidence and even no practical consideration) to assume the observed reality is something else unless there are new revelations.

  • One can reason in the spirit of Existentialism, that a human being is something, which is not yet a reality. Its reality is always a problem, not a fact. – Gelato di Cræma Sep 12 '14 at 23:27
  • @GelatodiCræma, yes, but only if we assume that the full potentials of human beings have not yet been discovered. – infatuated Sep 16 '14 at 19:13
  • @ infatuated It's interesting to imagine the situation when indeed the full potential has been discovered. Does it mean that from now and forever humans can do only one thing - to expand and to accumulate because they cannot expect anything new from themselves as humans? I guess there would be many who have became abated by this situation. – Gelato di Cræma Sep 16 '14 at 20:28
  • @GelatodiCræma, I am not sure what you meant by "expand and accumulate" however if we discover that human potentials are infinite, and therefore infinite levels for actualization of those potentials, then I'd believe upon the discovery there would be a passion and aspiration on the part of each individual for the full actualization of the revealed potentials. These speculations however are in fact based on my personal beliefs on what those potentials really are. – infatuated Sep 16 '14 at 20:57

If there were no reality, then all would be unreal. If all is unreal, then you are not real, your thoughts are not real, the statements you make are not real, there is no truth or falsehood, there is no reason, there is nothing but nothing (and not even empty space, since that's something. The verb "is" simply isn't available, period).

Thus, the person who says "we cannot really prove that there is a reality" is speaking nonsense. He's making a logical statement, containing meaning, conveying an idea that is falsifiable and has the capacity to correspond to other things or not correspond to them. His words have an inherent order, and while open to interpretation, there are many things they cannot be saying such as "the moon is made out of cheese."

It is therefore patently obvious that in the final analysis, in his very statement about reality, he's asserting that reality exists. One can't say anything at all without accepting reality. To try to do otherwise is a kind of gross and public self-pleasuring at the expense of other people's value and their comfort—though, if there is no reality, then other people don't exist, and it doesn't matter what we do to them, does it?

If words have meaning, then reality exists. If words don't have meaning, then I wish people asserting this would get their gratuitous and disgusting public self-pleasuring as far away from me as possible...

If a person asks "Does reality exist?", and thinks there's an answer besides utter nonsense such as "Zlopfnarglesoweiglawepqoijse"—even "well, we can't really tell one way or another"—then he is asserting that reality does exist.

There's a more compelling way to say this:

It's a category mistake (similar to asking what the color blue tastes like) to ask whether reality can be proven. You can't prove it, and it is meaningless that you can't. You also can't prove logic, or math. Have fun without those. You have to take reality for granted to do anything at all, and most especially to communicate with others on the nature of reality.


This is essentially the project of Descartes' Meditations. As you may recall, his aim was to find some aspect of reality capable of absolute proof, and his answer was that he could at least prove the reality of his own existence to himself.

He proceeded from that starting point to establish what he considered a proof of the existence of what we commonly perceive as reality, but most readers find that portion of his work less compelling.

You might want to read at least the first two of the Meditations if you never have, they are short, reasonably clearly written and freely available online.

  • He also went on to argue that existing meant having been created, hence having had a creator, hence having had a Creator. A bad case of putting Descartes before dehors. – keshlam Sep 13 '14 at 0:55
  • Worth adding that you don’t have to be a philosopher to read them. They’re fantastically engaging, or at least, I found them so, as someone who doesn’t find philosophy easy to read in general. – Peter LeFanu Lumsdaine Sep 13 '14 at 22:19
I think,therefore I exist.

Be sure to give a thought on these words because they much more than a simple sentance.

By being persuaded of either accepting that we are real or not you ARE a persuaded being.You can't be nothing if you ARE something even if you assume that that SOMETHING is nothing.Because no matter what you think you are a thinking something

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    This only really proves that there is a thinking something. What about the rest of the world? E.g. Do I exist? Can you prove it? – Einer Sep 12 '14 at 7:16
  • @Einer If you think about it our ability to perceive reality is a proof of reality. – Christo Sep 12 '14 at 7:28
  • Maybe your ability. From where you stand I'm still unproven. It could all be a dream of yours and all you are 'perceiving' is just an elaborate fantasy including an internet-guy nagging about your answer. – Einer Sep 12 '14 at 7:47
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    @Einer By being persuaded of either accepting that we are real or not you ARE a persuaded being.You can't be nothing if you ARE something even if you assume that that SOMETHING is nothing.Because no matter what you think you are a thinking something. – Christo Sep 12 '14 at 7:54
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    On the internet nobody knows you're the only verifiable existence. – 2rs2ts Sep 12 '14 at 23:06

This question has been asked and answered by so many different minds, and in so many different ways, that the only remaining issue of importance is how you intend to interpret the question and answer.

First off:

It is impossible to prove that reality exists.

It is impossible because, your ability to prove reality hinges on the existence of reality - and hinges on the existence of a reality that includes you - and includes you as a being capable of correctly interpreting the measurements and logic required to "prove" reality. If you were completely assured of your ability to correctly interpret your measurements and proofs of reality, it would be absurd to try and prove reality exists.

If you could somehow acquire 100% certainty that you were not deceiving yourself with your logic and with your tests, then you would not need to prove anything. You would already be 100% certain. Without 100% certainty, there is always the chance that there is something you are measuring wrong; or maybe you're just a brain in a vat somewhere.

And 100% certainty is impossible. I won't go into Plato's allegory of the cave (he used it for other purposes as well), but if you imagine you spent your whole life inside a cave never catching a glimpse of the sun, then you could prove a great many things that would instantly become nonsense the first time you saw the sun and realized your measurements were based upon (at best) incomplete data.

There are many thought experiments which cover this ground and suffice to say it is not possible to get anywhere close to producing something which resembles a proof that reality exists.

Now here's the next part of the question. What do you want to use this for? Depending on the context of the question, there are a great many pathways to increase understanding and intelligence.

Consider it this way: What do you mean when you say, "Does reality exist?"

Do you mean?

  • "Does what I observe with my eyes correspond with what is actually there?"
  • "What is the isness that I label 'reality' and in what manner can I understand this isness?"
  • "Do I have permanence?"
  • "Does anything have permance?"
  • "Is what I label reality a thing that can be qualified?"

These questions are unending. I think a far more reasonable challenge would be to try and come up with a new way to ask the question. The answers are in no short supply; and everyone "knows" that there answer is the right one. What would be far more interesting I think, is to come up with such a way to ask the question as to illuminate a new sliver of reality; to have the question itself be a work of art and a pathway to enlighten the mind.

Let's go do that.

Note: On rereading my answer, I realized that it may have come across as dismissive. That is not my intention. I love questions like that of the OP, because they stimulate the thinking required to respond.

  • But I notice you're personally sure enough of reality to write structured, falsifiable statements about it the topic--things that could not be if reality were not real. Even your statement "100% certainty is impossible" has an underlying 100% presupposition that reality IS real. You HAVE to act as though reality is real in order to say anything at all. Thus saying reality isn't, is nonsense. – ErikE Sep 26 '14 at 19:58
  • I didn't say that reality wasn't real - only that it's not provable. As far as I can prove, your comment is nothing other than a dream that's being had by some dreamer pretending that he has existence. The same goes for my answer. When I'm awake I know I'm awake, but I also "know" I'm awake when I'm dreaming. – dgo Sep 26 '14 at 20:22
  • But despite my comment possibly being unreal, you act as though it is. Since unreality immediately leads to the loss of all meaning, and the concomitant cessation of life (why eat, drink, or avoid pain if it's not real), there's no need to prove that reality isn't or isn't real, nor any useful distinction between provable reality and unprovable reality--since everyone does, and must, act as though reality IS real, or be shunned by all. – ErikE Sep 26 '14 at 22:57
  • Well...that was kind of the point of my post. Still, your answer offers nothing in the way of proof. – dgo Sep 26 '14 at 23:07
  • You can't prove logic or math, either--that doesn't mean they aren't legitimate. Reality not being provable is meaningless--it's a category mistake to say that. – ErikE Sep 26 '14 at 23:47

James Jean wrote in the Mysterious Universe - "To speak in terms of Plato's well known simile, we are still imprisoned in our cave, with our backs to the light, and can only watch the shadows on the wall...." and "Many would hold that, from the broad philosophical standpoint, the outstanding achievement of the twentieth century physics...is the general recognition that we are not yet in contact with ultimate reality."

Read "Quantum Physics and Ultimate Reality; Mystical Writings of Great Physicists" by Michael Green


The notion of a reality is most certainly not a proof. This can be demonstrated via counnterexample: I can have a notion that the Reiemann Hypothesis is true, but nobody in their right mind would consider that to be a proof thereof.

More interestingly:

'Reality' here would mean the universe and everything in it

This is an interesting definition. It's one that unravels in funny ways when you try to apply it. I mean, I can assign the word "boggmothafa" to anything I please and claim it's a thing, but what are its properties? What does it mean for reality to be a "universe and everything in it?" For example, one popular concept of "in it" is found in set theory. Nearly everything you've learned in both mathematics and science is founded in set theory -- meaning nearly every mathematical construct you use can be expressed in sets. They're a very natural concept which includes concepts of "including" its elements. However, when you then turn to the universe, you find that the universe is not a set. It's actually a class.

So what if I start from the assumption that the universe is a class? Well, it turns out its quite a lot harder to build proofs around classes. You'll find many of the things you really really really want to be true in reality are actually not provable in class theory unless you limit yourself to sets.

Also consider the Chinese Dao as an interesting counterexample. They might actually get away with claiming the Dao exists, because their approach doesn't pin the word to anything. Famously, "the dao which can be written is not the eternal dao." So in their sense, they handwave and say "there is a thing which exists and is everything," but they can't specify any properties thereof. They can only point in its direction. And you'll note in my word choice there, they assume the dao exists. It's an assumption akin to "I think therefore I am," but instead of being focused on "I" it's focused on something you're a part of.

I think the only reason you can say it is proven that the universe exists if you are comfortable with the assumption thereof. However, always remember that a skeptic can sweep that assumption out from underneath your feet.


To describe something you’re holding in your hand such as an ‘apparent’ apple as either “real” or “unreal” is a question of genuineness or authenticity. Either way you have a genuine apple or a genuine fake (representation). In this context you have useful information regarding affordances (J.J. Gibson) - a genuine apple is edible a fake one not. To describe “everything” (The universe as a whole) as either “real” or “unreal” seems to me like a categorical error.

Statements like “we cannot prove that there is a reality”, smack of folly, since they suggest that there is a ‘standard reality’ by which you can differentiate. If there is no benchmark reality by which to make a comparison, then I’d say the concept has no extension. Also the existence of just about everything (apart from what is normative/conventional or artificial) is not contingent upon whether you have a conception/notion of it or not. Either way the [Real(apple) V –Real(apple)] makes pretty good [Real(cider) V –Real (cider)], which gets me [Real(soused) V –Real (soused)], or better yet {Realy[Real(soused)]} V –{Realy[Real (soused)]}!


Reality is our perception whether a given phenomenon exists or not. The primary senses are the only way humans perceived the reality in the past. Senses are deceiving so people began to build philosophical arguments with the little information they get from the primary senses. Soon philosophy was merged with mathematics and theoretical sciences was born. In reality the physical phenomena are too complex to make as simple equations. So scientists began to take ideal cases where they could perceive very well and form simple equations. Even though they distorted reality they could perceive reality to certain extent. Experiments forced them to deviate from ideal cases and add other factors.

The same happens to human experiences. A child has very idealistic expectations of the world. Once the child grows into an adult, the past experiences make him/her perceive reality.

            Humans can perceive reality upto a certain extent. Reality is a relative term. There is no absolute truth or absolute lie. 
  • It's so tiring to hear that "There is no absolute truth or absolute lie." because gosh, that sounds like a pretty absolute statement, there. – ErikE Sep 26 '14 at 22:57

As a human being you only have one dependable perception of reality, and that is your own perspective through your own body. Everything else is bound to your imagination.

If you pick up an apple, and hold it in front of yourself and two friends - you could say there then exist 3 realities. Only you see through your own eyes and view the apple from your unique perspective, as your two friends.

Let us add in another twist - the side facing you is red, the side facing friend #1 is green, and the side facing friend #2 is yellow.

How does friend #2 prove their reality to you? The apple is red in your reality, but in theirs it is green.

They could hold up a mirror to allow you to see a hint, but it wouldn't exactly be a complete proof of their experience.

Perhaps they could connect wires from their brain to yours, so that you may perceive exactly as they do. But this act in itself changes the context... you are now experiencing two realities. In other words, there is no way their friend would be able to prove their reality to you as it was experienced by them. The mere act of showing you inherently changes their proof.

Our realities are our quantums. We own them, alone and by ourselves, but infinitely malleable and finitely experienceable. We can share bits and pieces with eachother, and then decide to trust or disregard eachother's realities.

Take another leap, and imagine if we were actually able to prove reality. Then you could say we have no reason to disregard eachother's realities, as they are provable. There would be no lies, no deception, but also no mystery and no great unknown. What a different world that would be.


I would say no. It cannot be proven because reality is derived from perception. If you see an apple, touch it, bite into it, and taste the juice, you are only perceiving it. Maybe its real, maybe you are hallucinating. Maybe you share the apple. If both of you agree that it is real is it? Maybe you are hallucinating the other person as well.

I think you will find that any attempt to prove reality requires you to either disprove a negative or have a point of comparison to a non negative. Meaning, you can't prove reality by contrasting it to a known fiction because you are then forced to disprove the fiction is reality first. I'm sure it is real to someone. Religion comes to mind here.

Also what happens to the proof if reality turns out to be a series of nested simulations? How could you ever know which one is the real one? http://en.wikipedia.org/wiki/Simulation_hypothesis

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    Where would the simulation be hosted? In another simulation? Is there a "master-simulation", hosting all simulation? If so, then there is reality. If not: Is it simulation all the way down? If so: Isn't that reality then? – Einer Sep 12 '14 at 16:47
  • @Einer, indeed. Absolute negation of realism is a form of sophistry but also one that is so easy to point out and expose. – infatuated Sep 16 '14 at 21:03
  • It's turtles all the way down. – dgo Sep 26 '14 at 20:23

There is a reality. A reality that'd explain what you perceive.

But as to proving that what you perceive is the reality. Obviously you cannot.

Famous movies have made this pretty clear. The Matrix (you can't with 100% certainty, rule out the possibility that reality is very different and 'perhaps' you are some human battery locked in a pod being fed a delusion). Or Total Recall, (you can't prove that your memories are real).

It's worth considering that but also, worth considering also dropping the notion of absolute certainty and look at things in terms of likelyhood and probability.


There is an idea, an a fair argument can be made in its defense, that the entire universe as we know it is simply some kind of simulation being done by some unknown and vastly superior intelligence. Evidence that leads to this idea is that the closer you look at the inside of an atom the more you begin to realize that there is no actual physical size to anything in the universe. That is to say that everything is made up of points in space that exhibit properties like gravity, but they have no physical size (like a video game simulation). Inside of a proton is smaller particles that are so small they may possibly exist merely as points in space reacting with neighboring points in space as their properties dictate.

Combining this idea with our own consciousness is a bit offensive to some people, but you only have to imagine the idea of a program/simulation that is so complex that the program itself believes that it is conscious and has free will (exhibit: Lt. Commander Data). Once you admit the possibility that such a thing can exist outside of yourself you are then presented with the question of whether or not it is possible that we ourselves are examples of such complex programs. It is certainly an entertaining idea in the least.

If such an idea were to be valid, it would also imply that a "god" exists as the creator, but this entitie's intentions and abilities however, still cannot be known.


Proving any statement is true or probably true is impossible, unnecessary and undesirable. This is true whether the statement is deemed to be philosophical or not. If you assess ideas using argument then the arguments have premises and rules of inference and the result of the argument may not be true (or probably true) if the premises and rules of inference are false. You might try to solve this by coming up with a new argument that proves the premises and rules of inference but then you have the same problem with those premises and rules of inference. You might say that some stuff is indubitably true (or probably true), and you can use that as a foundation. But that just means you have cut off a possible avenue of intellectual progress since the foundation can't be explained in terms of anything deeper. And in any case there is nothing that can fill that role. Sense experience won't work since you can misinterpret information from your sense organs, e.g. - optical illusions. Sense organs also fail to record lots of stuff that does exist, e.g. - neutrinos. Scientific instruments aren't infallible either since you can make mistakes in setting them up, in interpreting information from them and so on.

We don't create knowledge (useful or explanatory information) by showing stuff is true or probably true for reasons so how do we create knowledge? We can only create knowledge by finding mistakes in our current ideas and correcting them piecemeal. You notice a problem with your current ideas, propose solutions, criticise the solutions until only one is left and then find a new problem. We shouldn't say that a theory is false because it hasn't been proven because this applies to all theories. Rather, we should look at what problems it aims to solve and ask whether it solves them. We should look at whether it is compatible with other current knowledge and if not try to figure out the best solution. Should the new idea be discarded or the old idea or can some variant of both solve the problem?

So how should we assess realism? Let's suppose solipsism is true. You have just imagined the whole world. There are large parts of this imagined world that you can't control. If you walk across an imaginary motorway with your eyes closed you will be run down by an imaginary car and spend several imaginary weeks in an imaginary hospital. Your entire position consists of taking the world as described by realism and labelling certain parts as imaginary. This labelling doesn't solve any problem and ruins solutions to existing problems. Why did you just happen to imagine that dinosaurs exist? There is an explanation of why dinosaurs exist, but it involves the existence of a real world so solipsism denies that this explanation is true. Any theory that claims that something described by a current explanation doesn't exist suffers from a similar problem, including any other position that denies realism.

See See "Realism and the Aim of Science" by Karl Popper, especially chapter I and "The Fabric of Reality" by David Deutsch.


Ok this is rather simple.

My argument draws from Descartes: "I think therefore I am"

Thought occurs, therefore something exists (whatever has caused the thought or whatever medium the thought is happening in).

Descartes presupposes the existence of a thinker. In any case, this argument is simply a slightly more waterproof variant of Descartes'.

  • You wrote "I think", suggesting that you (the "I") are the one doing the thinking. To get your point across better, I think it should just be "Think." or "Thinking occurs. Therefore,...") – stoicfury Sep 16 '14 at 4:48

There is no way to prove it, beyond the obviousness of it all.

So one must choose to believe it because one likes it. That is all one can do. It's a particular aesthetic.


Well heres my attempt to prove reality: If reality isn't real, what is real? That last part has to be defined, if nothing is real then you are defining real incorrectly. We could define reality as not nothing, which in that case is true. We could say that reality is exclusive, that somethings cannot be real, as there are more unreal things than there are real things. If we define real as the math version of real, we are not imaginary as there are no tachyons (imaginary mass particles). If we want to be unnecessarily specific, we could say that reality isn't a simulation, in that case your proof is to find the limitations of the simulation, not just limitations in general. So I guess its very dependent on what you mean by real, and what is not real. So is the apple really an apple? What is not an apple? If its what an apple is not then it is so. We need to define what apple means. So I guess you answer your own question, what is real and what is not, where do we fall?


Scientists have proven that there is an objective reality each and every one of us plays a part in, but they have also proven that our perception of that objective reality is subjective and flawed in many ways.

Currently, there is growing evidence that our universe is a giant hologram. Does that mean that our universe isn't real? Or should we reassess what it means to be real? Personally, I would argue for the latter, as our objective reality is the only reasonable reference we have for what constitutes as real or not.

  • "Scientists have proven that there is an objective reality" is factually incorrect. To do empirical tests requires the assumption, or projection (to borrow from Nelson Goodman) of an objective, temporally unidirectional and causally ordered reality as background, or none of the tests would make sense. See amazon.com/Fact-Fiction-Forecast-Fourth-Edition/dp/0674290712 – Ryder May 12 '15 at 8:29
  • @Ryder : All the tests confirm the assumption that there is in fact an objective, temporally unidirectional and causally ordered reality and nothing whatsoever in any tests indicates otherwise. – John Slegers May 12 '15 at 10:12
  • increasing inductive confirmation is not the same thing as a proof, and the problem with that distinction is integral to the question at hand. If you want to re-define proof in such a way that it can include contingent propositions with arbitrarily small values of probability for any counterexamples (i.e., prove "there are no black swans"), you're free to do so. However, it's poor practice to retrofit your definitions without owning up to them and making it clear. – Ryder May 12 '15 at 12:53
  • @Ryder : I would be glad to consider any data suggesting that there isn't an objective, temporally unidirectional and causally ordered reality and adjust my answer accordingly. So far, however, it is my perception that all the data points exclusively to the existence of a objective, temporally unidirectional and causally ordered reality and as such I do not consider it relevant to consider any alternatives in my answer. – John Slegers May 12 '15 at 14:57
  • Again, that's fine– but you're applying a different standard of "proof" than has been asked for. – Ryder May 12 '15 at 15:10

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