On Philosophy

January 18, 2007

Our Model Of The World

Filed under: General Philosophy — Peter @ 12:12 am

Physically speaking all we have access to are the signals that go into our brains. When we look at how a perception makes its way to the brain there is nothing special about the visual input that makes it interpretable as visual alone. If we were to connect a display to the input of the senses it would just look like so much data. But from the “inside” of this system this is not the way it seems at all. We don’t feel like we are receiving arbitrary data, but rather seeing and hearing. And moreover our senses seem to have only one possible interpretation, they tell us about a world that exists independently of us, that contains all sorts of things, that behave according to their own laws.

Obviously the fact that we don’t interpret our senses as arbitrary data is a fact that can be explained by how our brains work. Our brains are simply set up to interpret data from different senses as being of fundamentally different kinds of things. And moreover it seems that our brain naturally interprets and structures this data, unconsciously, in terms of an independently existing world. But this solves only part of the mystery. We might accept the fact that we, by no choice of our own, interpret our senses in a certain way. But is this interpretation justified?

Now previously I have shown that the best explanation for our senses is that an external world, independent of us, exist, on the basis that a) no matter how hard you try you can’t affect the contents of that world without acting, and that b) the external world contains things that you didn’t know, but couldn’t be otherwise (like complicated mathematical proofs), showing that even if the world is not as it appears whatever is behind it is more complex than you mind. And this is part of the answer that we are looking for. The other part is to show that the interpretation we naturally give to our senses, about a three dimensional world that contains various everyday objects, ect is the correct one.

I have bad news; the interpretation that we give our everyday senses is not correct. The best science shows that the world, fundamentally, works in ways that are completely alien to us, for example of the quantum world. We live in this world, and although the data that our senses contain doesn’t directly point to this unusual structure, it is still what ultimately is behind our perceptions (or at least it is an approximation of some even more fundamental reality, which can certainly be only more strange). And it isn’t quantum physics alone that has brought us to this realization, although it is the most obvious example. We perceive the world as being made up of objects, when in reality there is no such thing as an object, simply an uneven distribution of matter. Much of our intuitive conception of the world revolves around these nonexistent objects, we give them properties, we expect them to interact in certain ways, and we conduct our lives as if objects were the most fundamental part of the world. Usually this is a workable description of the world, but it doesn’t explain everything, and the explanations that do don’t include objects (only X, where X is what the current theory says is the fundamental constituent of nature). So the world we perceive doesn’t really exist, at least not as we perceive it.

But the world we perceive isn’t a total illusion either. For example, if you see a train coming you should probably get out of the way, otherwise you will have an unpleasant experience. Although the world as we perceive it may not reflect the underlying reality perfectly it does a very good job, especially in the situations we usually find ourselves in. The world we perceive should be thus best thought of then as a good approximation, or a convenient and useful model, of the real facts. Let me put it another way. The data we receive from our senses can be interpreted in many ways. One model is the world we are used to living in, but surely there are other, much more complicated, ways as well. But the world, as we conceive of it, is by far the simplest of these, and the most reliable for generating predictions as to what will happen next.

Thus I think that we can trust our experience of the world to be a decent, although imperfect, reflection of what is really out there. But it is also important to remember that we can’t trust it completely. Because our model of the world contains objects of various kinds, and their properties, we can’t really trust it in full. Believing that the world really is exactly as it seems leads to bad science, and bad philosophy. A good example of this problem is ancient Greek philosophy. The Greeks were good reasoners, but unfortunately the philosophy that came to dominate their thought (post-Socrates) only rarely took into account the possibility that the world might be other than it appeared (with a few notable exceptions), and thus we ended up with forms and categories. Of course this problem still crops up again occasionally in modern philosophy. We should be suspicious whenever we are told that something is obviously one way or another, except when it is something that we construct (not part of the objective world) or when it couldn’t possibly be otherwise.



  1. Objections in brief.

    1. Your model of the brain interpreting sense data seems a bit homunculus-like.

    2. The world is like we think it is. I think water will make me not thirsty, and it does; I think trains can kill me, and they can; I think the pyramids are in Egypt, and they are; I think my fiancee loves me, and prolly so. Atoms and quantum junk are maybe true, but that doesn’t invalidate ordinary experience, unless in ordinary experience we feel the irresistible need to make up impractical theories about what things are like on a microscopic scale. Even if that’s the case, our macroscopic intuitions stand.

    3. The suggestion that the Greeks didn’t consider the world to be different than it appears is a bit bizarre. Thales? Parmenides? Heraclitus? Democritus? The beauty of the post-Socratic era was that it came up with a rebuttal to these theories of the difference between reality and appearances that reconciled the difference, but people never forgot that the challenges had been made and as a result Skepticism flourished as a serious school for centuries.

    Comment by Carl — January 18, 2007 @ 2:03 am

  2. 1. It’s just the way the brain works. The brain gets signals, that’s all it gets.
    2. Read the last two paragraphs. I didn’t say the world we perceive isn’t often a good approximation of what is really there, indeed I said the exact opposite. But there is a difference between being a good approximation and being right (as in true).
    3. Thales, Parmenides, Heraclitus, and Democritus were all pre-socratics, and I quote myself “but unfortunately the philosophy that came to dominate their thought (post-Socrates) only rarely took into account the possibility that the world might be other than it appeared”

    Comment by Peter — January 18, 2007 @ 2:12 am

  3. 1. I don’t dispute that the data is unlabeled, but the way you describe it, it seems like a little man in my brain is getting unlabeled floppy disks then figuring out what’s on them. However, the activity of the data in the brain is what makes data what it is. It’s like a LISP program, the data is the application. So, it’s not that there’s data and then an interpretation. The data is the interpretation.

    2. I argue that common sense is “true” not just an approximation. Admittedly my assertion depends on whether common sense claims to describe the microscopic (I claim it does not) and the nature of truth.

    3. I know that you said post-Socratic. I guess I’m nitpicking about the meaning of “rarely” in “rarely took into account.” I mean, it’s not like Aristotle’s 4 elements (+ ether) theory is that much more common sense than chemistry. It still argued that “this looks like ‘steam,’ but really it’s fire plus water becoming air.”

    Comment by Carl — January 18, 2007 @ 2:42 am

  4. 1. A lisp prgram is only a lisp program when you have a lisp intepreter, it does not interpret itself, magically. And yes the brain does impose an interpretation on the data see paragraph #2, which, as I pointed out leaves the validity of the interpretation unanswered.
    2. Common sense says: there are such things as chairs. Science: there is no chair, only a bunch of atoms you think of as a chair, there is no “chairness” in nature. Therefore common sense is wrong. Common sense also says that space is euclidean, and in fact few people can even visualize a non-euclidean space. But space is non-euclidean, so again our model of the world that we have (and contintue to have in spite of knowing better on an intellectual level) is wrong. Old common sense also included: the earth is flat, the sun goes around the earth, ect. Even our modern common sense contains errors about the nature of the world, it is just that on reflection we realize them to be errors, and that we unlearn the silliest mistakes when we are little.
    3. I’m primarily thinking of the forms, neo-platonism, ect, which dominated philosophy for quite a long time. And aristotle was a big proponent of ontology / division of nature based on self evident categories, which in turn were based on grammer. He also thought that forms existed in addition to matter and combined with matter to make objects, which was a big part of his theory about change.

    Comment by Peter — January 18, 2007 @ 2:53 am

  5. And if anyone ever said: “this looks like ’steam,’ but really it’s fire plus water becoming air.” they are quite odd. Who speaks of “fire” combining with things? We might say heat, but only after defining heat to mean molecular motion, and not as a substance, at which point you wouldn’t speak of it combining with water. And no one would maintain that steam is air either. Air is O2 + N2 + ect. It becomes gaseous water, which is very very different from air.

    Comment by Peter — January 18, 2007 @ 2:56 am

  6. Another example: you throw a ball. Common sense: the ball followed a curved path. Science: the ball followed a straight path through curved space-time, and although I know this I will never be able to see it, my model of the world will always involve curved paths.

    Comment by Peter — January 18, 2007 @ 3:22 am

  7. Aristotle would say steam is air made from water plus fire. He considered fire a substance made from fire-type matter.

    Also, re: 2. my definition of chair is not, “Thing made up of a solid, continuous substance.” It’s “thing that can be used for sitting.” Science does not deny the existence of chairs in my sense!

    Comment by Carl — January 18, 2007 @ 3:46 am

  8. My common sense is, “If I follow a curved path, I can predict the path of the ball.” Science denies it not!

    Comment by Carl — January 18, 2007 @ 3:52 am

  9. Science doesn’t deny that you can make rough predictions, science syas your model of the world by which you make these prediction, which does cotnain chairs and curved paths, is wrong, as in not true. Am I incorrect, when you look outside do you see everything moving under the influence of gravity alone as going in a straight line?

    Comment by Peter — January 18, 2007 @ 11:05 am

  10. And I quote “It still argued that “this looks like ’steam,’ but really it’s fire plus water becoming air.”” which it is not, to the best of my knowledge.

    Comment by Peter — January 18, 2007 @ 11:06 am

  11. Oops. That was a typo? “It is still argued…” should be “Aristotle argued…”

    I find my typing bizarre sometimes.

    Anyhow, what does it mean for a model to be true? If it makes good predictions, what else is there?

    Comment by Carl — January 18, 2007 @ 12:45 pm

  12. Although our model of the world makes good predictions it also makes many bad predictions, while the scientific model makes much better predictions, both in accuracy and over more cases. For example if someone had a model of addition that worked for the numbers 1-10 but failed otherwise would you say that their model of addition was true, if they primarily encountered only those numbers? No, we would say it was false because it didin’t give the correct result in all cases. Likewise our model of the world does not give the correct result in all cases, thus it is false, and not the best explanation of the data provided to us by our senses.

    Comment by Peter — January 18, 2007 @ 1:19 pm

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