(June 7, 2015 at 4:44 am)Alex K Wrote: Pyrrho,
I'm not saying we want ultimate truth. But do the explanations which we take from theories not tell us something true about the world. I think even you make that assumption regularly and that one can't do entirely without.
I think it depends on what you mean.
To give a philosophical sort of problem, somewhat suggested by JuliaL above, let us consider the old idea of a brain in a vat (which is easier for modern people to understand than the otherwise better example of a disembodied mind or the possibility of everything being a dream).
Suppose you go to sleep tonight as usual, and go into a coma. You are found to have some sort of terrible disease infecting your body, but some genius doctor has come up with a plan to remove your brain and has figured out a way to not only keep your brain alive, but to hook up a computer to all of your brain's inputs and outputs, and to recreate your entire world. So that when you try to raise your arm, the computer receives that input, and outputs such that you get the sensation of lifting your arm, etc. If this were done perfectly, for you, your life would be indistinguishable from having an actual arm, etc. The start, for your new experience of being the brain in a vat, is you waking up in your bed the next day, as if nothing happened. We can add more fun to the example, and imagine your brain is in a bomb shelter, with the computer and your life support powered by a nuclear reactor, or geothermal power, or some other such independent power supply. Imagine the U.S. and Russia finally use the weapons that they have spent so many billions (is it trillions?) on and detonate all of their nuclear bombs, and imagine all other human life is destroyed. Only you remain. Your life in the bomb shelter goes on, unaware of what has happened to everyone else. You interact with the computer, which has simulated your wife and everyone else in your life, so you are blissfully unaware of this, and continue on as normal.
Now, imagine that this happened last week, so that right now this is your life. Or imagine that it happened to you as a fetus, so that your entire life outside the womb has been computer generated. In that case, it may be that the writer of the program thought it would be good fun to change you into a primate, when really you are a lizard which normally has 8 legs and 10 eyes. Maybe the programer has totally altered the laws of physics for your universe, and all of that is completely different from the way the real world is as well. So what you are doing, Alex, is just reverse engineering the computer program's version of physics, and not discovering anything about the way the universe actually works.
Now, what is the point of this sort of story? The obvious point is that one cannot know that this is not the case (if taken as given). The less obvious point is that it does not matter. This second point is worth drawing out a little bit. Suppose you are the brain in the vat. You put your imaginary hand into an imaginary flame, and it hurts terribly, just the same hurt as it would be if you had a real hand that you put into a real fire. The program is well-written, so that the "next day" you have imaginary burns on your imaginary hand, and if you had it in the imaginary fire too long, your imaginary fingers were destroyed, just the same as if you had a real hand kept too long in a real fire.
Notice, it does not matter whether you believe you have a real hand or are just the brain in a vat; you still want to avoid sticking your hand in a fire. Unless, of course, you want the pain, and want the consequences, of that action.
Most people prefer the story of having a real hand and there being real fires, and so they tend to believe that story. But the story does not matter for any purpose one might have. The story of a real hand does not add value to anything, it does not explain anything, it is totally irrelevant to everything that you know or do. It is completely and totally irrelevant to anything you can do. It makes no difference at all in your life.
Here is another story, one that I rather like more. (I am hiding it because some people don't like long posts and may want to scroll down past this. They are likely to miss the point of this post if they ignore it, but people may do as they please.)
"A wise man ... proportions his belief to the evidence."
— David Hume, An Enquiry Concerning Human Understanding, Section X, Part I.
