A Primer on the Doomsday Argument
anthropic-principle.com
A Primer on the Doomsday Argument
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Re: A Primer on the Doomsday Argument
#2Is there a strong, formal version of the Doomsday argument not based on cubicles and such? The obvious flaw in that version is that it is based on finite possibilities: that is, finding oneself in this or that kind of universe out of so many possible ones.
For starters, we have no idea of how likely our universe is; we know what numerator is 1, but what goes on the denominator? Is there even such a number? If so it is something so huge that the probability is vanishingly close to zero.
Then what about the parallel universes hypotheses: what if the universe is constantly fragmenting into multiple futures. In one future, I will submit this comment and close the tab, then check my e-mail. In another, I keep the tab open and go make a coffee.
This proliferation of multiple futures from any moment would tend to provide a way for doomsdays to be circumvented.
If you are cloned into N futures in this moment, and you're killed in N-1 of them, then you don't know it; by the anthropic principle itself, only the surviving future matters; there is no consciousness in the others. The suriviving future has no idea about the size of N, either.
Re: A Primer on the Doomsday Argument
#3"If the Doomsday argument is correct, what precisely does it show?"
That philosophers are not statisticians?
Re: A Primer on the Doomsday Argument
#4Is this a restatement of the Fermi Paradox?
Re: A Primer on the Doomsday Argument
#5Is this a restatement of the Fermi Paradox? http://en.wikipedia.org/wiki/Fermi_paradox
No, it attempts to quantify how many humans are alive at a point in the future.
Re: A Primer on the Doomsday Argument
#6"If the Doomsday argument is correct, what precisely does it show?" That philosophers are not statisticians?
That philosophers take their arguments too seriously?
I mean, this is fine as an interesting thought exercise. To the degree that you take it seriously as applying to the real world, to that degree you need... something. Perspective? To not take fine-sounding argument so seriously? To take a long walk? To get a life?
Not everything that cannot be logically disproven is true. Not everything that cannot be logically disproven should be acted upon as if it were true. It is useful to know when to smile at the philosophical earnestness and then just go on with your life.
Re: A Primer on the Doomsday Argument
#7> The last step is to transpose these results to our actual situation here on Earth
Yeah, that's the trick, isn't it? Is the metaphor truly valid? This how philosophers differ from scientists: they see no need to test their hypothesis with real-world measurement. This is also why philosophy needs to go the way of alchemy and astrology - as an amusing but archaic belief.
Re: A Primer on the Doomsday Argument
#8My favourite answer to the doomsday argument: The many worlds hypothesis is correct and we haven't created our "world ending" p=np computers yet. (Literally halt if randomly generated solution is incorrect and catch fire to every sentient being in the world).
Another possibility is that we're very close to building realistic simulations, and by induction, it makes sense that we're at this stage of development.
Re: A Primer on the Doomsday Argument
#9>Now we modify the thought experiment a bit. We still have the hundred cubicles but this time they are not painted blue or red. Instead they are numbered from 1 to 100. The numbers are painted on the outside. Then a fair coin is tossed (by God perhaps). If the coin falls heads, one person is created in each cubicle. If the coin falls tails, then persons are only created in cubicles 1 through 10.
>You find yourself in one of the cubicles and are asked to guess whether there are ten or one hundred people? Since the number was determined by the flip of a fair coin, and since you haven’t seen how the coin fell and you don’t have any other relevant information, it seems you should believe with 50% probability that it fell heads (and thus that there are a hundred people).
The conclusion in the last sentence is incorrect is an incredibly subtle way. Since 10 times more people are in cubicles in the heads case, the probability that you find yourself in a cubicle at all is ten times higher in that case, which affects your prior. By Bayes' theorem:
P(HEADS| WAKE UP) = (P(WAKE UP|HEADS) * P(HEADS)) / ( P(WAKE UP |HEADS) * P(HEADS) + P(WAKE UP|TAILS) * P(TAILS) )
= (10 * P(WAKE UP|TAILS) * P(HEADS)) / ( 10 * P(WAKE UP|TAILS)* P(HEADS) + P(WAKE UP|TAILS) * P(TAILS) )
= 10 / (10 + 1)
= 10 / 11, or about 91% chance of heads given that you find yourself in a cubicle.
Re: A Primer on the Doomsday Argument
#10Is there a strong, formal version of the Doomsday argument not based on cubicles and such? The obvious flaw in that version is that it is based on finite possibilities: that is, finding oneself in this or that kind of universe out of so many possible ones. For starters, we have no idea of how likely our universe is; we know what numerator is 1, but what goes on the denominator? Is there even such a number? If so it i…
The big gaping hole I see is that the blog post at least doesn't treat the earlier epochs with the same question. If a person in 1000 CE took up the same question, would they predict Doom Early or Doom Late? If everyone for the last ten thousand years would predict Doom Early, that seems like a piss poor predictor.