interesting concept

[gasgod]

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okay i think i follow now

what i meant the whole time was randomly selected number, not random number, my apologies for the confusion

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Can your birth number be a randomly selected number? Quite obviously not

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not obvious to me

and btw, as far as i can see this is not a paradox

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Can you describe the process by which your birth number was randomly selected? All you did was to look in the mirror and say "I hereby select you." Hardly random, since every other human being -- past, present, and future -- was excluded from the selection process.

But my argument is even stronger, since we can show that no such random process can even be imagined unless we know the range.

The Doomsday argument may not be paradox in the usual sense, but you must admit that it seems a bit silly that a few words and numbers can predict the future of mankind.

GG

[WhiteWolf]

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IMO you could use this argument to say cards are not random, once you are dealt 72, the odds you have pocket aces is exactly 0

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To me, it seems the method to select the cards you are dealt (shuffling then dealing) is random, but the method you use to assign 'birth numbers' (first person born gets #1, etc) is not random.

Edit: Hopefully this makes my idea clearer:

If I shuffle and deal you a card, I will have no idea what card you have. I can say, however, that there is a 1/52 chance it is the A of spades, a 1/52 chance it is an A of clubs, etc. This is a property of a random event.

I also have no idea what your birth number is, but I can say that the the chance it is 1 is exactly zero, and the chance that it is 1 trillion is also exactly zero. If birth numbers were truly randomly assigned, I would not be able to say that.

[Jazza]

okay so you and gasgod don't like one of my assumptions -

that we were 'dealt a random hand'

to me it seems very reasonable to assume, i can't prove it of course, but basically i think that if you took any person on the earth and right after that person was born you could state that it is just as likely that this person was born in the first half of all people to ever be born than be born in the last half of all people ever to be born.

and this person has a 25% of being in the first 1/4 of people ever to be born and so on

i guess i'm just restating my assumption here, but here's my question to you guys:

if we weren't 'dealt a random hand', just in what way is it not random?

[PairTheBoard]

This is in response to posts above by Master Shake, Jazza, xorbie, gasgod, Girchuck, and Whitewolf.

Suppose there are Two Urns. One contains 10 balls labeled 1-10, the other contains 10 million balls labeled 1-10 million. Suppose a fair coin is flipped to decide which urn a ball is chosen from. Before you look at the ball you would say there's a 50-50 chance it was drawn from Urn 1 or Urn 2. Now, say you look at the ball and see it has #7 on it. You don't need to do the Bayes calculation to know that it's Far Far more likely the ball came from Urn 1 than Urn 2. #7 is indeed much different than #3,245,876. This is essentially the kind of argument being made by Doomsday. The discussion should be about why the Doomsday scenario is Fundamentally Different from this Two Urn Scenario.

Here's another example where it's easy to see the difference. It's the Incubator. There's a Jail with 100 cells. An observer is created and placed in cell 1. A fair coin is flipped. If Heads, nothing more is done. If Tails, 99 more observers are created and placed in the remaining cells.

Now, you are an observer in one of the cells. You know you were created via this process. Not knowing what cell you are in, you conclude there's about a 50% chance you are alone and in cell 1 and about a 50% chance you are a random member of a group of 100 and equally likely to be in cell 1-100. Now suppose you look outside and see that you are indeed in Cell 1. What do you conclude? By Bayes you conclude that the odds are huge that the coin was heads and the other 99 people were never created. The difference between this and Doomsday is easy to see. In Doomsday the real situation is that you are in Cell 1 and are STILL WAITING for the Coin to be Flipped.

PairTheBoard

[gasgod]

[ QUOTE ]
okay so you and gasgod don't like one of my assumptions -

that we were 'dealt a random hand'

to me it seems very reasonable to assume, i can't prove it of course, but basically i think that if you took any person on the earth and right after that person was born you could state that it is just as likely that this person was born in the first half of all people to ever be born than be born in the last half of all people ever to be born.

and this person has a 25% of being in the first 1/4 of people ever to be born and so on

i guess i'm just restating my assumption here, but here's my question to you guys:

if we weren't 'dealt a random hand', just in what way is it not random?

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A number, in and of itself cannot be random. Suppose I told you that 1729 was a random number. What test could you apply to determine whether it was random or not? Unless you knew how the number was chosen, you would have no reason to judge whether it was random or not.

Whether a number is "random" or not depends on how it is selected. When you assume that a birth number is random, you necessarily assume that the method for choosing it is random.

In the doomsday argument, assuming that your birth number is 'random' is simply invalid. It is like assuming that 97 is greater than 100. You cannot assume the impossible.

GG

[Jazza]

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In Doomsday the real situation is that you are in Cell 1 and are STILL WAITING for the Coin to be Flipped

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we are?

you don't think there's a chance the coin has been flipped already?

one of my assumptions was that the total number of people to ever be born is some number X, i.e. the coin has been flipped already

[Jazza]

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In the doomsday argument, assuming that your birth number is 'random' is simply invalid. It is like assuming that 97 is greater than 100. You cannot assume the impossible.

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i don't agree with this, i don't think what i'm assumming is impossible

the way i see it you have no reason to assume it's not random, IMO the simplest explanation is that it was 'randomly selected'

[gasgod]

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Suppose there are Two Urns. One contains 10 balls labeled 1-10, the other contains 10 million balls labeled 1-10 million. Suppose a fair coin is flipped to decide which urn a ball is chosen from. Before you look at the ball you would say there's a 50-50 chance it was drawn from Urn 1 or Urn 2. Now, say you look at the ball and see it has #7 on it. You don't need to do the Bayes calculation to know that it's Far Far more likely the ball came from Urn 1 than Urn 2. #7 is indeed much different than #3,245,876. This is essentially the kind of argument being made by Doomsday. The discussion should be about why the Doomsday scenario is Fundamentally Different from this Two Urn Scenario.

[/ QUOTE ]

Selecting one's own birth number is not the equivalent of drawing a ball from an urn. In selecting my own number, I have excluded from the selection process every number not equal to my own. I have no right to simply assume that my number is somehow 'random'. If the process of selection is non-random, then the result cannot be considered random.

Ask yourself this question: Is it possible to to choose a birth number randomly without knowing the range of possible numbers? If not, then asserting that one's own birth number is 'random' is to assume the impossible.

GG

[Jazza]

i think i found our fundamental difference, you see it as us selecting the number, i see it as us being given the number

[gasgod]

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In the doomsday argument, assuming that your birth number is 'random' is simply invalid. It is like assuming that 97 is greater than 100. You cannot assume the impossible.

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i don't agree with this, i don't think what i'm assumming is impossible

the way i see it you have no reason to assume it's not random, IMO the simplest explanation is that it was 'randomly selected'

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How can you say that your birth number was randomly selected? You were the one who selected it, and it just happens to be your own. In effect, you have said: "I am going to select my own birth number at random." This is just silly.

GG