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How much of our life is in our minds

  1. Apr 8, 2005 #1
    Ive been reading most of the posts on this board, and from the "how much of our life is in our minds" post I came to think of something ...how can anyone proove anything to anyone else? Some people would say that science is prooves things but I think it's just sort of making an attempt to prove something... Can we proove we exist? Can things be proven? does proof exist or is EVERYTHING a speculation?
  2. jcsd
  3. Apr 8, 2005 #2
    read decartes meditations!

    my analysis might be a bit rusty, but here's what i remember.

    the first meditation deals with how we can't trust our senses because we might be dreaming. however, our sense of logic is intact.

    the second meditation deals with how we can't trust our logic either, because we may be being controlled by an evil demon (many analogies have been made to The Matrix, if you've seen it)

    the third meditation... is not worth reading, IMHO. it's a crappy "proof" of god's existence, that contradicts his earlier meditations. however, many scholars believe he only added this proof of god's existence due to pressure from the church. keep in mind, he lived around the same time as galileo, who was sentenced to house arrest for contradicting the church. this is further supported by the enscription on his gravestone, which translates to "he who hides well, lives well". sneaky bastard!

    i haven't read any of the other meditations.

    anyway, i think it's the second one that states the famous "Cogito ergo sum", or, "I think therefore I am". his philosophy was that you can doubt that I exist, or you can doubt that the Earth exists... you can doubt pretty much anything. However, it's hard to justify doubting doubt. If you doubt doubt exists, there is still doubt! a better phrasing of his words might be to say "Doubt exists.", and that's all we can prove. make of it what you will.
  4. Apr 8, 2005 #3
    A proof relies on a certain number of basic, self-evident assumptions that can't be argued with. The hard part of proving something isn't finding the proof, but finding these assumptions that everyone can work with.
  5. Apr 9, 2005 #4
    Decartes sounds interesting......

    Icebreaker, so a proof is based on ASSUMPTIONS, which are self evident... ? Maybe I dont understand this but If its based on assumptions, is it really proving anything?
  6. Apr 9, 2005 #5
    Can you do it any other way?

    Different assumptions allow you to prove different things. The key is finding the logical assumptions that are self-evident. If something you're trying to prove is not self-evident, then break it down, look at it and see if you can spot any ambiguities in the components -- anything that can be refuted, or anything that simply doesn't make sense; if so, break them down further until you arrive at the fundamental parts of the argument which are self-evident while eliminating the flawed ones. If you can rebuild your original argument with these, then your proof has merit.

    How well you can break them down and analyse them determines how rigorous your proof is. This applies to any field.
  7. Apr 9, 2005 #6
    But surely, an assumption is mearly speculation or 'what you think something will be' and 'what you think something will be' is most definitely speculation.

    IMO, Rygars post makes the most sense. We can only doubt everything - except doubt itself - as doubting something is doubt.
  8. Apr 10, 2005 #7
    If you assume nothing, then you can prove nothing.
  9. Apr 10, 2005 #8
    Nothing can be proven then, except doubt... ?
  10. Apr 10, 2005 #9
    Everything is an illusion, except that that creates the illusion.
  11. Apr 10, 2005 #10
    This post seems to be filled with nice little sayings, but I think we aren't really getting anywhere.
  12. Apr 10, 2005 #11
    Here's another one for good measure. No one can be told the truth, that is something for each of us to figure out on our own. Philosophy and religion can only point to truth. This question is at its core a philosophical question. Hence, you are right in your assessment saying "we".
  13. Apr 10, 2005 #12
    i don't think there's any answer to this. no, technically, you probably can't prove anything at all.

    but does that mean it's not worth trying?
    i don't think that's true. there is a long list of major philosophers that covered these issues.

    do you really need something to be 100% justified to take it as fact? if it's not conclusive, does that mean it's a mere speculation? maybe justification is a sliding scale, and not a dichotomy?

    i guess to me, i have that small spot in my head that says "yeah, descarte is right, we can't prove anything"... but it's overshadowed by a plethora of inductive evidence that states elsewise. so if i can't justify induction (which no one can, by the way), i guess i'm screwed.

    but i'm not going to sweat over it, because the world i live in is all i have to go by!
    sure, i guess it's true that a lot of evidence used to "prove" something would be based on inductive premises, but if it's all i have to go by, i'll take it over nothing!
  14. Apr 11, 2005 #13
    Descartes' best quote (to my mind) is :

    If you would be a real seeker after truth, you must at least once in your life doubt, as far as possible, all things.
    Rene Descartes, Discours de la M├ęthode. 1637


  15. Apr 11, 2005 #14
    I agree that all "proofs" ride on the back of assumptions (or axioms). There is no proof in existence which does not somewhere assume something.

    I think one can sum up "truth" in one phrase : "logical consistency"

    I believe our world must be logically consistent (ie we could not be living in a logically inconsistent world).

    This means that whatever view we have of "truth" or "reality", we must always endeavour to ensure that it remains logically consistent.

    Aside from this - anything is possible!

    The only question that remains is : Is there more than one possible logically consistent world?

  16. Apr 11, 2005 #15
    Well, to give a mathematical example: non-Euclidean geometry.
  17. Apr 11, 2005 #16
    I will try to re-direct this thread to what I think the auther tried to discuss.

    First, I can ussume something, it doesn't mean that you have prove it. I can assume that E=mc^3 but it isn't it's E=mc^2 and only the fact that I ssume that it is the first equation, it doesn't mean it's correct.

    Secondly, someone said up there that everything is an illision except that that created the illusion. Well, that leads to paradox.......If everything is an illusion except, and only except that that creates the illusion, then the illusion itself isn't an illusion, contradicting it's own meaning, but if the illusion is an illusion, it is contradicting the statement.

    Thridly, here we are asked if it is possible to prove, and if this is able, how to prove and why this is to proof. Not about what most people are talking which is about what proving is. But lets define proof, maybe this is ok: the demonstration of something. It can be via many ways, it can be proof or disproof, it can be proving something true.... Now, if proving is the demonstration of something, how can we demosntrate something? Really, I'm not sure that we actually can. We know what it is, and it's nature, but we can do it because most probably it is something that depends on nature. If any of you knows how to prove and why that is a prove, please tel me because that I really don't know.
  18. Apr 12, 2005 #17
    which is an example of a geometry; not (with respect) an example of a logically consistent world.

  19. Apr 12, 2005 #18


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    And the non-euclidean geometry of Lorentzian spacetime. This is not proposed as a logically self-consistent world? Not a model but an assertion that this is the way the world really is? (I know there are objections to this from the particle physics community, but Freeman Dyson, for example, isn't persuaded by them).
  20. Apr 12, 2005 #19
    No, it is proposed as the "geometry" of a logically self-consistent world.
    The map is not the territory.
    And the geometry is not the entirety of the world.

    The world is not asserted to be non-Euclidean; even if the "geometry of the world" may be asserted to be non-Euclidean.

  21. Apr 15, 2005 #20
    Moving finger, I was following you up until you said logical consistency... What exactly do you mean by this?

    Our views on reality must be consistant because there is no real way of proving anything.. so we have to follow some model? And make it logical?

    Also you agreed that all proofs are based on assumptions... Does that make them proofs? Is proof meant to be based on assumption or does proof mean no assumption?
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