Wednesday, March 31, 2004

Skepticism and the Matrix

The skeptic argues that none of our beliefs are really justified, because we have no way of knowing that the world we perceive is the "real" one (e.g. we could be in the Matrix).

The Skeptic's Master Argument:

1. Most of my knowledge about the world depends upon the reliability of my perceptions (e.g. I 'know' I have two hands, because I can see & feel them).

2. It is possible that I could have all the exact same conscious experiences that I'm having now, even if none of them were "true" perceptions (e.g. I could be in the Matrix, and never realise it).

3. Trusting in my perceptions is not justified, unless I can prove (at least beyond reasonable doubt) that they are perceiving reality (i.e. prove that I'm not in the Matrix).

4. I cannot prove beyond reasonable doubt that I'm not in the Matrix.

Therefore, 5. I cannot truly know that I have two hands. (Or, more generally, my beliefs about the world are unjustified.)

"Isn't that a bit improbable?"
The most natural response (the first time you come across the skeptic's argument) is to say "well sure, anything's possible, but it's surely not very LIKELY that my whole life is an illusion!?"

The problem with this response is that it begs the question. There is no way for us to assign probabilities to these rival metaphysical hypotheses. Of course realism SEEMS more likely to us, but this judgement is made based on assumptions we have picked up from our perceptions and everyday life. In other words, realism only seems more likely if you've already assumed realism to be true. If judged objectively, there is no possible evidence which could suggest that realism is ANY more likely than anti-realism, because all our subjective experiences would be exactly the same in either world.

My Solution:

I would answer the skeptic by identifying various different "worlds" that we can talk about, and then asking which of these worlds we are refering to when we claim to have knowledge.

Particularly, I want to distinguish between the "Objectively Real World" (or RW), and the "Common World" (or CW). To explain these terms and make this distinction clearer, consider the scenario portrayed in the Matrix movies. In this case, the RW is that which is ruled by the machines, which humans are blissfully unaware of (forget about Morpheus & co for the moment). The CW, by contrast, is the world inside the Matrix.

It is this matrix-world that humanity have in common, that people talk and argue to each other about. Moreover, I suggest that it is this Common World that is the appropriate domain of knowledge, rather than the external RW outside the matrix. Consider Joe, who just got fired (and knows this fact). One might argue "well, he didn't actually get fired, since none of it is REAL", but I think that rather misses the point.

All knowledge is about some particular world, and purports to represent that world accurately. It thus allows us to explain (& perhaps predict) things about that world. For Joe, who knows he just got fired, which is the relevant world? What events is he trying to explain? What sort of future events is he trying to predict? The answer is evident: he is concerned with the world of his experience, the world where he lives and interacts with other people. In short, he (and his knowledge) is concerned only with the CW, not the RW. As Joe's belief (that he got fired) accurately represents the state of affairs within the CW, we must consider it to be true within the context of the CW. There is no reason to deny that Joe does indeed have knowledge - it is simply knowledge about the Common World, rather than knowledge about the Objective World.

Just in case you doubt that knowledge and truth properly belong within a particular framework, consider another example: Bob is talking to Bertha, and says to her "I had this dream where I was walking down the street..." - and suddenly Bertha interrupts, shouting "Liar! You were lying in bed asleep!"

Bertha's response is quite obviously inappropriate in this case. She is imposing an impractically strict notion of truth, restricting it only to the "real" world, which proves to be a serious (and pointless) obstacle to meaningful communication.

I suggest that the skeptic is making the same mistake. By demanding that our knowledge be about truths of the "Objectively Real World", the skeptic is missing the whole point of knowledge and communication. We are not generally interested in discussing some abstract RW. Instead, normal discussion is concerned with (and takes place within the context of) the Common World which we share and experience. Whether it is "objectively true" or not is irrelevant. Propositions about it can be true within the appropriate context, and that is what matters.

We can have knowledge about the world of our common experience. This crucial and undeniable point is overlooked by the skeptic. In the end, all the skeptic can say is that we cannot know whether the world of our common experience is the "objectively true" world or not. But this is of no great concern, since in our day to day lives, we are not really concerned with some abstract notion of objective truth. Instead, we try to make sense of this world we find ourselves in. No easy task, of course, but not nearly so grim as the skeptic makes out, either.

Update: I notice that Prof. David Chalmers has some similar ideas.


  1. [Copied from old comments thread]

    Having faced similar things in History of Science, I pretty much came to the same conclusions as you (just on Monday during the lecture, actually).

    All the quibbling by atomists over what really makes up the world, and whether movement and change actually exist or not - none of it really matters in the end, because the world is how it appears to be to us, and even if we're wrong, there's no way to prove it either way, and inquiring into these problems is unlikely to shed much light on any problems we might have to face.

    I guess this could be seen as a bit short-sighted - it was people inquiring into how things work that allowed us to discover chemistry, for example. But I think there's a bit of a difference between wondering "is that arrow really at rest?" and wondering "can I turn lead into gold?".
    Lanthanide | 1st Apr 04 - 6:41 pm | #


    Ha, yes, and there's an even bigger difference between "is that arrow really at rest?" and "is that arrow real?"

    I'm afraid I don't know anything about those 'atomists', but from what you describe, I wouldn't necessarily be so quick to dismiss them.

    After all, at least what they're studying is the world we live in (the "common world"). Sure, they're investigating it at a level which is far beyond our usual day-to-day perceptions of it. But it's still the same world.

    So it's at least possible that their findings may ultimately have some use, isn't it?

    (unless i've misinterpreted your description of them.)
    Richard | 1st Apr 04 - 7:22 pm | #


    A Skeptic would say that you're simply assuming the existence of other minds with whom communication about the Common World is possible. The Matrix is a bad example in this respect, because in the Matrix scenario it's true that there are other minds, including machine minds like Agent Smith, even though the rest of the Common World for those plugged in is a computer simulation. The skeptic's question is what if Neo were the only mind in the world, and everyone else, including Smith, were simulations? The utility of accepting CW as true in order to facilitate communication with other minds doesn't enter into it then. Nor is the Skeptic asking for a direct pipeline to an unknowable level of reality. There is a perfectly perceptible reality that Neo could experience if he could just get unplugged.
    What you have, IMO, is an argument for rejecting Platonism, not for rejecting Skepticism.
    Joshua | Email | Homepage | 8th Apr 04 - 3:00 am | #


    Yeah, good point. But I don't think it troubles my argument too much.

    After all, most of what I'm saying here does not actually depend on other minds at all. Of course, the "Common world" would have to be renamed "My world" (MW)... but propositions can still be true (and known to be true) with regard to My World.

    The only question remaining is whether my knowledge-claims purport to describe MW or the RW. As before, I still think the pragmatic answer (MW) is more appropriate - even without the possibility of communicating with other (real) minds.
    Richard Chappell | Email | Homepage | 8th Apr 04 - 11:24 am | #


    Good example Richard. Assuming that this refutes skepticism (I think it does but time will tell), it seems to me like it is also reasonable to assume the existence of other minds (because the world of my perception contains beings that appear to act and react similarly to me, and I can create a very coherent system of beliefs about MW that incorporates other's minds).

    Do you think this is very close to positivism? Also, note that you used 'context' a bit in your discussion. Do you think this is a form of contextualism (standards that change being what 'world' you are talking about)? Could be useful for that essay!
    Patrick | Email | 10th Apr 04 - 9:21 am | #


    Yeah, I'm not exactly sure where my solution fits. It does seem vaguely positivist/idealist (are those the same thing?) in that the world of our perception is considered to necessarily 'exist' (in at least some sense). However, unlike them, I do not deny the existence of an objectively real world.

    Some of Hilary Putnam's writings on Semantic Externalism also seem to gel nicely with this view. (He suggests that "tree" in vat-English refers to a "tree-in-the-image", rather than any objective tree, and so the Brain-in-a-Vat is indeed saying true things.)

    But I think this probably does fit best as a form of contextualism. Note, however, that I'm not suggesting we change the standards of evidence at all. Instead, I'm suggesting that we change what world we are talking about depending on the context.

    That is, what I offer here is perhaps a sort of metaphysical contextualism, which is quite distinct from the usual sort (epistemic contextualism).
    Richard | Email | Homepage | 10th Apr 04 - 11:38 am | #


    Oh yeah, just for the record: Patrick originally came up with that example I gave about the dreaming "liar".

    (I didn't bother mentioning it at the time because Blogs don't require the sort of detailed referencing that essays etc do.)

    So many thanks for that
    Richard | 10th Apr 04 - 11:46 am |

  2. Hello Richard,

    I just stumbled upon your remarks to the brain-in-a-vat scenario. I think you left out one serious point in your consideration (and David Chalmers in his also), and that is: In the matrix it is possible to reach into the RW. Neo is woken up by Morpheus to learn that he lives in the matrix. If a skeptic worrys about whether he lives in a Matrix or not (or whether he is a brain in a vat or not), your argument will not be of great help to him. For it may be true that he "knows" something about his world, but he will not know until he wakes up whether he is in a matrix or not. And if he wakes up, like Neo, he will think that all beliefs he had had about himself and the world he lives in, are false.

    Usually the question is handled in terms of a "disquoting" language. That means that the language of the brain in the vat, just as mine, is "fully disquotional" and the truthmaking scheme <"I'm a brain in a vat" iff I'm a brain in a vat> can be applied. You give Putnams argument a metaphysical twist; I have already read a book (I hope your german is good enough :-)) by Olaf L. Müller that fully outlines the metaphysical consequences of the BIV-Szenario.

    For Müller's Book look on his page

    My Blog:


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