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Originally posted by simonm
Well, you've gone straight ahead to take the bull by the horns by tackling generalised statements first.
I'll get to the fine statements if you want me to. :)
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However, you seem to make a point that we can know these statements are true beyond all doubt and then gradually retract from this position towards the end of your post.
It wasn't my intention to retract from that point of view, but I can understand why you are thinking that. I guess my stance is, you can't simply make a statement, you have to make sure that no one has observed a contrary.
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You are suggesting that you can be certain of the truth of a generalised statement because it has never made a false prediction (or an observations has never been made that contradicts it). You are saying that it is true because it has not (yet) been falsified. But, just because a statement hasn't been proved wrong does not mean it's been proved right, does it?
You cannot be absolutely certain that it is correct because it makes predictions for an infinite number of hypothetical situations and you would only know it were true, beyond all possible doubt, if you lived for eternity and witnessed each of the infinite number of situations.
This is true, but futile. We have to decide on a method (a scientific method). That method leads us to believe that "everything falls down". Yes, this may not be the absolute truth. There may be something that falls up, that posses the tendancy for anti-gravity, but no one has ever reported such a substance, so we have to stick to what we know. If we wanted to ignore Newton simply because of what might be, then we had no reason to listen to Beurnoulli (sp?), since it is obvious that man can't fly because he is composed of too much earth and not enough air.
So I guess from a philisophical point of view, no, you can never declare a undoubtedly true statement, since you can't know all the possibilities. But to take this approach gains you nothing. It is terribly impractical. It is akin to living in fear. Why should I drive to work since I could die in a car crash. Why should I believe in gravity since there may be an exception.
So my stance is, yes, you can declare a statement that can be cleared of all reasonable doubt. The difference between these two statements is pure mental masturbation. While one may enjoy it, it is a waste of resources and doesn't compare to the real thing.
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However, you go on to mention Einstein's Space/Time theory. This theory has essentially replaced Newton's theory of gravitation. Why did it replace Newton's theory? Because Newton's t heory does make false predictions for very large masses (such as planets).
Einstein's theory is a better explanation for the phenomenon of gravitaiton and hence is considered closer to reality than Newton's theory.
Here I thought Newton's theories failed because they didn't accurately describe the why, just the what. What Newton observed is still true, but Einstein supposed a why.
Semantics. In any event, Einstein paints a sharper picture, but Newton's wasn't wrong, just fuzzy, and used as an example since it is much easier to write.
PS: I still hate the "feature" of vBulletin that forgets what forum, what thread, and what message you wrote if you take too long writing it.