I am new to philosophy and I have been looking for a way to find answers to my disturbing doubt for a long time, I was reading Berkeley but I did not find a convincing refutation, especially because what they say to refute "the master argument" seems to me a misinterpretation of their thought or at least what I think it is, since I had these thoughts long before reading Berkeley or any idealist.

My question is the following: If all we perceive is the sensible world, how can we ensure that something like matter exists? Even if we could make sure that matter exists, what would it be? I take the example of the matrix film, they live in a virtual world, where stimuli are controlled by machines, that is, true reality exists but all the stimuli that come to us of "real objects" are artificial stimuli. So if you are inside that virtual world, how can you make sure that there is another reality? Assuming that it exists.

There are two questions.

It's something that I can't get out of my head and I can't find an answer, I've been thinking about this for days and I'm desperate.

  • Comments are not for extended discussion; this conversation has been moved to chat. – Philip Klöcking Feb 16 at 15:57
  • If for your peace of mind you need a 100% water-tight unrefutable proof that matter exists, you are in the wrong forum. There's only one area of human knowledge I know of where proofs are accepted without question: mathematical theorems based on axioms and definitions. No philosopher can help you to be absolutely certain. All you can do is try to accept that your perceptions reflect the world that all the others accept. But philosophy can be useful for figuring out what we mean by "matter." – Timm Feb 17 at 13:52
  • @Timm Mathematics is part of philosophy – Voxywave Feb 17 at 15:33
  • @Voxywave That would surprise a lot of mathematicians! While there are some philosophers who do use mathematical methods to gain some rigor in their search for truth, the idea of mathematics being a part of philosophy is a pretty far-fetched notion. But don't take my word for it. Look here: Quora: difference between maths and philosophy. – Timm Feb 18 at 15:30
  • Sorry to say, in more than 60 years listening to English and several years following at least a dozen SE groups, I have never seen the form "…what are the proofs…" used by an educated native speaker; much less "…what are the proofs to…" In your case, what could "… to affirm…" change? In any case, what might "… all we see is the sensible world…" mean? – Robbie Goodwin Feb 18 at 23:13

12 Answers 12


Since you are talking about "prove", I'll take a materialistic standpoint in my answer.

If all we perceive is the sensible world, how can we ensure that something like matter exists?

We cannot. That is the age old argument of Plato's Cave. It is fundamentally impossible.

Even if we could make sure that matter exists, what would it be?

We cannot know. If you ask current-day physicists, they will tell you all about the quantum realm, but the fact of the matter is that they also do not know what matter actually is.

To give you an example: the Greeks figured out that there must be "atoms" by way of the argument that you can split whatever matter you have many times, but at some point down the line there must be an end to splitting. They called that thing "atom", which literally means "unsplittable". It turned out that at every point in time in our scientific history our understanding of what are the unsplittable constituents of matter were basically wrong. Atoms are made up of electrons and the core, the two of which separate all the time (e.g. in electricity and all kinds of chemical processes). The core splits easily into protons and neutrons by way of all kinds of everyday processes. We can smash protons etc. together and they explode into many other pieces. Matter converts into energy, energy into matter; none of those bits and pieces are like little billiard balls, but much more abstract - it's all a big mess.

So the probability that our current Standard Model as we have it now is the final last word is... unlikely to say the least, especially as we are not even close to explaining gravity in the quantum realm yet.

But the more pertinent argument is that all we do when trying to figure out the universe is again just observing and thinking. Observing is always just an indirect process. Photons hit atoms and subtly change their wavelength (hence, color), and thus we infer properties of the atoms. Smaller things are even more indirect, we can only smash rocks together and see what happens with the explosion (which is what CERN does) - not much more than what the Neanderthals would do.

At no point in human time has there ever be even the tiniest glimpse in any methodology or way to look behind the curtain. For all intents and purposes, unless you build a grand logic or spiritual building and start believing religiously in that, it is impossible for us, as far as we can tell now.

An even deeper argument is that as far as we know, we are 100% made up of the same matter as the kind of matter we are reasoning about. We are simply too crude. If what the string theorists propose is true, and there are many-dimensional entities flitting around, vibrating at unfathomably high frequencies, then it will be absolutely, fundamentally, unchangeably impossible to ever even observe these things, or prove anything to a degree which would make everybody happy.

I take the example of the matrix film, they live in a virtual world, where stimuli are controlled by machines, that is, true reality exists but all the stimuli that come to us of "real objects" are artificial stimuli. So if you are inside that virtual world, how can you make sure that there is another reality?

You cannot. By our best estimate today, the brain gets all its information through nerve endings strewn through the body, and these are simply electrical and chemical messages traveling along a cable. If an entity is technologically able to plug your brain into a lot of cables, and trigger them in the right way, there is in a quite fundamental sense no way whatsoever you could know about that, or break out of it.

If you want to get even more confused, read the classic paper Are we living in a computer simulation; then relax. It will all be well.

  • I really liked your answer. I like when science is combined with metaphysical questions. – Voxywave Feb 17 at 12:07

If all we perceive is the sensible world, how can we ensure that something like matter exists? Even if we could make sure that matter exists, what would it be? I take the example of the matrix film, they live in a virtual world, where stimuli are controlled by machines, that is, true reality exists but all the stimuli that come to us of "real objects" are artificial stimuli. So if you are inside that virtual world, how can you make sure that there is another reality?

If "everyone*" sees a sees a rock, feels the pain as they kick the rock, and hears the rock go thump as they hop around in pain, and then feel disoriented as they fall over... does it matter whether or not it's a mass shared hallucination and that we're all actually in pods controlled by machines, or electrons in a giant simulation?

I assert that it does not matter.

This "shared acceptance" of reality is how we determine if someone has a disease of some sort: if you're hearing voices telling you to kill President Biden, and no one else is, then either:

  1. The Machines in The Matrix are implanting the idea,
  2. the beings running the simulation are implanting the idea, OR
  3. you're sick and need to see a doctor right away.

Occam's Razor says "see a doctor right away" even though we might actually be in a simulation.

* Except, of course, the blind who can't see, the paraplegic who can't kick, and the deaf who can't hear, but we can discern that they are different and accept their inability to sense the world like we do.

  • Your thinking is like my thinking. It is for this reason that I ask the question, because I constantly see a dispute between materialists and idealists when in reality it does not matter, we live in a reality, is it a shared, independent, imposed, solipcist reality? If you can't prove it WHAT MATTERS – Voxywave Feb 15 at 1:40
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    @Voxywave the uncharitable answer is that highly intelligent people who don't want to get productive jobs scam society by becoming Philosophers, wowing the not-as-intelligent with their indecipherable gibberish while sponging off of others. – RonJohn Feb 15 at 1:46
  • Of course, if we sincerely doubt the evidence of our senses, then we don't even know for sure that there is a "shared acceptance" of reality: maybe we're alone and hallucinating, or alone in a pod controlled by machines, or the like. – ruakh Feb 16 at 19:53
  • @ruakh my answer specifically addressed everything in your comment. – RonJohn Feb 16 at 20:03
  • @RonJohn: I don't think it does. It does mention the possibility that "you're hearing voices telling you to kill President Biden, and no one else is", but retains the assumption that you know no else hears those voices. My point is that if we sincerely doubt the evidence of our senses, then there may not be any "shared acceptance of reality", because we have no idea what anyone else thinks, or indeed whether there is anyone else to think anything. – ruakh Feb 16 at 20:23

Assuming you believe that perception requires a material substrate (just how we think perceiving requires the brain, or a computer), then you can reason as in Descartes and say that the fact you perceive something (or appear to) is proof that there is something doing the perceiving.

If you don't believe that perception requires some material substrate, then I don't see how to do this.

  • That is the point. Common sense says, if we can perceive something it is because somehow the matter that causes this exists, you can try to corroborate your ideas with science and that certainly would be prudent. But this is one of Berkeley's points. If we were to be guided by a cause-effect relationship, we would never finish discovering which is the true cause of everything (true matter), it would be an infinite loop. – Voxywave Feb 14 at 20:45

Berkeley's immaterialist arguments are quite interesting. And since philosophy does not defer entirely to experimental "proof," metaphysical arguments can't be flat out "proven" or "disproven" in that sense. One must examine the coherence and assumptions in the argument.

First, Berkeley is not arguing for a Matrix-type skepticism. He would argue that sensory experience of objects is perfectly "real," only it is not caused by something "behind" or "below" our experiences in the sense of Kant's noumena or Locke's primary qualities. That includes some inert underlying substance we cannot perceive named "matter" in Newtonian mechanics.

So Berkeley is a very strict empiricist. All we have are "experiences" and our recombinant "ideas" about experiences, such as memories, imagined things, which are all like shakier, fainter experiences. All of these he calls our "ideas," only some are very vivid and immediately sensed. It makes no epistemological sense, he argues, to discuss things like "matter" that could on principle never be experienced. Though, of course, we can make up signs and names as matters of convenience.

The most famous refutation of Berkeley's idealist empiricism is Samuel Johnson's, who said "I refute it thus!" and kicked a stone. This appeals to the "common sense" idea that there is a vividly distinct ontological class of mind independent objects, an argument which can also be demonstrated in a less terse, comical fashion.

But again, Berkeley is not to be misunderstood as a skeptic. Experiences are real. Empirical science is valid. His primary aim amounts to a novel proof of God by a careful examination of materialist, mechanical doctrines, particularly causation. Like Hume and Hegel after him, he believes material causation is simply "constant conjunction" observed by a mind. It is not something essential and universal beyond observation.

For Berkeley, only minds are active, creative, and "cause" things. We know this for certain because we, as finite minds or spirits, can immediately create or "cause" new ideas and new experiences. Though we cannot seem to cause those "ideas of sense" or what we would call "objects." Thus, he believes, we must account for those things my some other mind, since mind is the only creative or "causal" force we immediately experience. Causation or creation cannot arise from something presumably inert and never even experienced, called "matter."

So we get the same "common sense" world, only mind comes prior to matter, which creates nothing but is itself created by mind, not our own finite minds but infinite mind. Why, Berkeley might argue, do we insist on imagining an infinite, dead, inanimate universe preceding and surrounding minds, which somehow arose out of it? This chicken-egg conundrum is contrary to what we in fact know most immediately and vividly, which is experiences and a mind unifying them. We have no "experience" of unconsciousness prior to or distinct from consciousness. How could we?

So, rather than rehearse "mind independent" arguments against Berkeley, of which there are many, I'm just pointing out that he is not a skeptic, not saying that our experiences are illusions or that there is something "behind" the matrix of perceptions "causing" our delusory ideas. His arguments are not meant to raise doubts, but to relieve us of the mistaken abstraction that we are inexplicable sparks of mentality fallen into a vast, dead, mindless universe that immediately extinguishes us. He might wave his hands at all that we are experiencing now and reply to Johnson "I refute it thus!"

  • I agree that Berkeley's vision is not only to put materialism to the test but also to give a coherent explanation of what we see and relate it to his worldview (that of a creator god). But notice that I myself, agreeing with some of the objections that are put to materialism, its conclusions derived from these do not seem to be entirely valid, what I am saying is that saying that there is a god incurs the same problem of believing in the matter. That is why I say that Berkeley was misinterpreted, I am not saying... – Voxywave Feb 14 at 21:23
  • ... that Berkeley was a skeptic, but I do not find convincing refutations to these skeptical arguments with which immaterialism starts, and I think that is the true master argument. (I reposted the comments because I was wrong to put a word) – Voxywave Feb 14 at 21:24
  • @Voxywave, In a more direct response to your question, you can find a very concise refutation of Berkeley's immaterialism in Russell's History of Western Philosophy, Ch. 16. – Nelson Alexander Feb 16 at 0:07

Short answer: We can't know that something like matter exists. You are perfectly right, we only experience our sensible world, and there is nothing to prove that there is more behind our perception than that we perceive it.

Long answer: We should still accept the fact that matter exists as our working hypothesis. Simply because of Occam's Razor: It is the simplest possible explanation of our perception, especially once you factor in all the physical experiments that have been performed. These physical experiments have proven over and over again that what we call matter behaves in certain well-defined ways. We would not expect such an extreme level of consistency if we were just dreaming our perceptions.

Final note: Just as Descartes noted, there must be something real that does the perception. Even if our perception is just a dream, I can be certain that at least I must exist, and again, the simplest explanation is that the world I perceive is real, and that I'm just like the other people I see walking along on the streets.


Another approach is semantic externalism: "meanings aren't in the head". Hilary Putnam argued for it:

Imagine a planet mostly the same as Earth, but with no H2O, only a alternative substance (say XYZ) that's a biologically adequate substitute. The humans living there even call it water. But on the planet, water doesn't mean what it means here; it means XYZ, because of the world shaping their language.

Putnam argued that a brain in a vat doesn't have the right experiences to have accurate definitions of terms, so statements it thinks in its language will be false. So if it thinks "I'm a brain in a vat", it's wrong, just as its thoughts are wrong in general. But if even a brain in a vat can't accurately think it is one, then such brains don't exist.

This argument is related to the principle of charity. If you try to translate a recently discovered tribe's language, you have to assume their beliefs about the world are largely accurate, like your own, otherwise you can't fathom a guess at what they're likely saying when they say statements, or asking when they ask questions. Even though a brain in a vat remains logically possible, Putnam has rendered it too unworkable a scenario to reason intelligibly about. We can't really get anywhere if we think our experiences are too misleading for us to learn from them. By contrast, realism, even if only representational realism, is much more operable than any attempt at near-global scepticism about the empirical world.

I like externalism because of the light it casts on Quine's attempted dissection of the analytic-synthetic distinction. His "married bachelors" thought experiment involves a world different enough for terms to mean something different there, so that the fact that "all bachelors are unmarried" has a different truth value therein may be ascribed to the definitions being different rather than to the truth value depending on more than terms' definitions, which is what would happen if the statement were synthetic.

  • Good answer, though I'd like to point out that Putnam has brought forward arguments both against internalism and externalism. Tim Button's The limits of Realism does contain a nice, structured reconstruction of the arguments, including a section where the logical inconsistencies of various arguments are laid out formally. – Philip Klöcking Feb 15 at 8:54
  • @PhilipKlöcking Thanks, I'll read Button if I get a chance. My knowledge of Putnam on this is not only selective but second-hand. – J.G. Feb 15 at 9:36

You mention seeing in the title question, generalize to perceiving in the body, so I suggest that the impression of solidity in haptic perception supports the belief in "matter." It might be objected that "science says" that solid objects are "made up of" a lot of "empty space," that solidity comes from electromagnetic repulsion, etc. but electrons are counted as matter particles so if we countenance them, we countenance matter. Roughly. (Air is not seen as solid but wind can push against us as if it were...)

Generalizing again, though, what is matter supposed to be? Descartes thought that extension is material as such, so perceiving space is itself perceiving matter. If we abstract to pure substance, this seems more like a cognitive imposition--we don't directly see that something is the essential subject of impressions, but presuppose this description by applying the logical form of our language to the possibility of experience. I.e. to unite our bare sense of space and time, we think of a substrate in all space that represents the permanence of time, and this ends up as pure matter. But we only perceive this inasmuch as we perceive space and time; otherwise pure matter is invisible (intangible).

  • What books do you recommend to extend this last explanation? I feel that it is a good point but it does not convince me, perhaps because I do not understand enough what is meant by extension and what it means to think about space-time. – Voxywave Feb 14 at 21:50
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    The argument/explanation comes from the second edition of the Critique of Pure Reason. – Kristian Berry Feb 14 at 23:51

The sensible world indicates that something (call it physical reality) exists outside my mind because my perceptions, when analyzed critically, exhibit enormous coherence far beyond that of my purely internal thoughts.

In principle, a simulation or virtual reality could be indistinguishable from a "true" reality. However, in practice, each layer of simulation requires vast resources to maintain fidelity, and introduces the possibility of errors that would undermine coherence.

Whatever its ultimate nature, reality is accountable -- it surprises me sometimes (indeed fills me with wonder), but with enough effort I can track down reproducible causes and make successful predictions (science), including something as simple as the persistence of objects. And when I make mistakes in my thinking, reality intrudes (sometimes painfully so) and I can typically identify what mistakes I made. I have to accept that some inconvenient things are true in reality even when I desperately wish they weren't.

Practically speaking, I use this idea implicitly when I wake up from a dream. I know I'm in reality, and not just another dream, when I observe the overwhelming, accountable coherence that is absent in hallucinations -- e.g., the proverbial "pinching myself" where sight, movement, and touch align perfectly.

I can drill down in almost endless detail and still find coherence. So many different kinds of evidence -- my memories, written records I can see, statements I can hear from other people -- turn out to be consistent (or explainably inconsistent) in ways that would be implausible for me to orchestrate a priori in my mind.

In everyday life I constantly rely on the fact that what I can't currently, personally know or perceive nevertheless has a reality. If I lost something, I may be able to say it's either here or there, and definitely not both places at once. I can investigate and learn where it is, and will find that it has had all the effects it should have had if that's where it was.


From my philosophical understanding regarding the ontological world (ie, your definition of matter in your question), so far no metaphysical theories can prove its existence or not. Though all natural sciences are dealing with the relations between seemingly all "material" stuffs, but actually sciences are dealing with the relations of all the perceptions of the ontological world reflected in our rational human mind, which happens to be capable of reasoning and organizing all these reflections (concepts, notions, statements, theorem, laws, etc) into the whole current human knowledge. In short, all human understandings are essentially metaphoric reflections, which can be reflected totally differently even from the same ontological reality as different possible theories.

So regarding the ultimate ontological matter/reality/truth (or whatever you may call it), no one can be sure what it truly looks like or even exists at all. What we're sure is there're definitely impressive marks left in our mind from our surrounding "reality". Actually there're basically 2 schools of speculation about the underlying "material reality" based on our human perceived experiences: materialism & idealism. Similar to your assumed position as majority of people will tend to agree, materialism speculates the ontological "reality" is really nothing but materials similar to what we feels, stable with certain forms, some fluid, some rigid, some gaseous, ultimately they're composed of atoms/quantum particles, etc, maybe endless in this fashion... While a small number of people tend to have a bolder opposite view called idealism, which claims what really exist in the ontological "reality" is nothing but conscious beings and substances, like God's images similar to us human minds. Matter actually does not exist ontologically, it's just an illusive sensation or reflection of some other perceptible or conscious substances.

One naturally will be very doubtful about the speculations of Idealism, sounds super natural and mystic. However, there're two main arguments supporting it:

  1. It avoids dualism, basically there's only one type of real existence ontologically, namely perceptible substance (most people call God or the equivalent, Leibniz called Monads), it explains why human mind as only a small part of the whole world, however, can understand much more beyond its body and seemingly can grow its knowledge of the whole containing world indefinitely. Using mechanical reductions as in physics, it cannot be satisfactorily explained "Why part can understand whole? Why "I" exists?" yet. While if one admits the only real ontological substance is some bare perceptual or advanced conscious being which can conceive ideal concepts such as sensations or math notions, then haven't all modern sciences taught us all phenomena can be explained from those ideal concepts?

  2. One can always infinitely divide any matter which always has some geometric extension, in this fashion you cannot hold onto any remains to claim "this is the final holy grail real matter!" because you still can divide it further no matter how small. Much like modern quantum physics shows the whole atom is nothing but curved spacetime tightly structured to feel like material, but actually is a immaterial field. Leibniz famously followed this infinite dividing thought process to arrive at the mystic but ideal concept called infinitesimal "dx" which has no geometric extension (thus immaterial) and cannot be intuitively experienced at all.

Hope this can alter your insistence to prove matter exists ontologically. In a word, ideas can only be conceived thus born from the ideals...

  • Certainly your answer and the others give me a lot of peace of mind, I thought I was crazy since I could not find answers like these. Each answer given in this question gives me a lot of peace of mind. – Voxywave Feb 15 at 3:04
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    Many times from my own observation, watching too much without true understanding will just confuse you further, it's a common phenomena everywhere in this world throughout history... that's why although philosophy/belief/religion is of utmost importance, but very few studies and emphasizes. – Double Knot Feb 15 at 3:15

Assume the opposite: Matter doesn't exist and it's all a simulation. What changes would you make to your life? Can you come up with any substantive conclusions based on the supposition that nothing exists?

There are infinite simulation scenarios with unique and disparate objectives. In the face of overwhelming uncertainty of truth and impact, the only sensible solution is to assume that all that we sense is, for all intents and purposes, real.


There is no sufficient way to decide whether the signals that comes from our sense to our mind are caused by "real matter" or a simulation thereof. However, there are ways to probe to some limit I will specify later whether the universe is a simulation or not:

A simulation run by a computer is limited to run turing computable algorithms. However, not all possible computer programs are turing computable. For some turing-machines operating on the input on their tape, we cannot decide whether they will eventually halt or not and even if they halt whether the answer they give is correct (The Halting Problem and problems which can be reduced to the halting problem).

So there are algorithms which may never terminate on their input. If some physical law is not turing computable, or in other words there exists no way to compute it with an algorithm on a computing device, the universe could not be simulated by a computer with the strength of a turing-machine equivalent model of computation.

There are theoretical candidates like the spectral gap, The classification problem for 4-manifolds and a few others. Showing that a physical law is not turing computable would imply the universe to be not the kind of simulation that could ever be run by our classical computers (Which includes in this context quantum computers).

It should be noted that there are stronger models of computation collected under the term Hypercomputation. These include models of computation which allow even the halting problem for turing-machines to be solved. The observable universe, if not turing-computable, could still be hypercomputable in which case you would be unable to differentiate simulation and reality either way. Thus, if the observable universe is a simulation, we could still probe to some degree that extent of computational power of the computing device (Could be a dream of a Boltzmann Brain for all we know) which runs the simulation.


If all we see is the sensible world, what are the proofs to affirm that matter exists?

Call an "ontological set" for a given person, the set of all things which that person asserts exist, (or alternatively the set of all things which that person asserts are real or which that person asserts are actual or some other similar term).

Suppose a given person excludes from that set "matter", on the grounds that he or she cannot directly perceive matter.

Would that person not be required, to maintain consistency, to exclude "other minds" from the ontological set as well? Is not the existence of "other minds" just as much something we infer from our experiences, rather than perceive directly, as "matter" is something we might infer from our experiences, rather than perceive directly?

This is not a proof that "matter exists". However, it is an argument that if one wishes to exclude "matter" from one's ontological set, one may end up excluding more than one bargained for. One may be logically obligated to adopt solipsism.

  • @MathKeepsMeBussy Even if it were so, that would be an argumentum ad consequentiam. But I don't think there is only one option, these are my assumptions: 1) Matter exists 1.A) God created matter (we live in a simulation) 2) Matter does not exist 2.A) God is the mind of God ( Berkeley) 2.B) I am my own god (solipsism) – Voxywave Feb 21 at 17:39
  • Yes it is an argumentum ad consequentiam. I'm not sure that is "bad" however. Sometimes we do not like the logical consequences of how we choose our ontological set. ++++ I don't know what you mean by "these are my assumptions", then give 1 "matter exists" and 2 "matter does not exist". – Math Keeps Me Busy Feb 21 at 18:11
  • I mean that solipsism does not necessarily follow from the statement "there is no matter." And from the statement "matter exists" it cannot be concluded that there is no god. – Voxywave Feb 21 at 18:17
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    @Voxywave No, solipsism does not necessarily follow from the the statement "there is no matter". However, solipsism may follow from the reasons given for asserting "there is no matter", in particular, if one asserts immaterialism on the grounds that matter is not directly experienced, then one is faced with the problem that other minds are also not directly experienced. Also, you are correct that "matter exists" does not entail "there is no god". – Math Keeps Me Busy Feb 21 at 18:19

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