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The Doomsday Argument

dylancatlow
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1/9/2016 9:32:12 PM
Posted: 11 months ago
"The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far. Simply put, it says that supposing that all humans are born in a random order, chances are that any one human is born roughly in the middle... Assuming that the world population stabilizes at 10 billion and a life expectancy of 80 years, it can be estimated that the remaining 1,140 billion humans will be born in 9,120 years. Depending on the projection of world population in the forthcoming centuries, estimates may vary, but the main point of the argument is that it is unlikely that more than 1.2 trillion humans will ever live on Earth."

Unfortunately, if the argument is fundamentally correct, the estimate of 9,120 years is far too generous. For much of human history the chances that someone would ponder this question was close to zero. Thus, the "60 billion humans who have been born so far" is the wrong sample to look at, since there was no chance we would be asking this question during much of that period. The relevant sample consists of the people who ponder the question, which is pretty much confined to people born in the last few decades.

Possible counterarguments:

1. "The a posteriori observation that extinction level events are rare could be offered as evidence that the DA's predictions are implausible; typically, extinctions of a dominant species happens less often than once in a million years. Therefore, it is argued that human extinction is unlikely within the next ten millennia."

Humans are simply not comparable to other species in this regard. Other species don't have nuclear weapons or the ability to rapidly destroy the environment.

2. "Another objection to the Doomsday Argument is that the expected total human population is actually infinite."

This is probably the best counterargument. If the age of the universe is infinite, and if this entails "everything happening an infinite number of times" then the doomsday argument collapses.

3. "One objection is that the possibility of your existing at all depends on how many humans will ever exist (N). If this is a high number, then the possibility of your existing is higher than if only a few humans will ever exist. Since you do indeed exist, this is evidence that the number of humans that will ever exist is high."

This is a terrible counterargument. There are countless "potential people" who don't exist, but who never get to ponder any of this. The only examples of people we have are those people who exist. Thus, those who ponder the question i.e., us, are not "randomly selected" out of all the possible people, but rather out of the people who exist. In other words, it's not as if all potential people were laid out on a table, and when we closed our eyes and randomly pointed to one they happened to exist. That *would* imply that a significant portion of potential people end up existing. Rather, what we have amounts to an extreme form of selection bias.

4. "The Bayesian argument by Carlton M. Caves says that the uniform distribution assumption is incompatible with the Copernican principle, not a consequence of it.

He gives a number of examples to argue that Gott's rule is implausible. For instance, he says, imagine stumbling into a birthday party, about which you know nothing:

Your friendly enquiry about the age of the celebrant elicits the reply that she is celebrating her (tp = ) 50th birthday. According to Gott, you can predict with 95% confidence that the woman will survive between [50]/39 = 1.28 years and 39["50] = 1,950 years into the future. Since the wide range encompasses reasonable expectations regarding the woman's survival, it might not seem so bad, till one realizes that [Gott's rule] predicts that with probability 1/2 the woman will survive beyond 100 years old and with probability 1/3 beyond 150. Few of us would want to bet on the woman's survival using Gott's rule."

In the absence of any knowledge about biological lifespan, this would be a reasonable estimate. If we make no assumptions about how long humans live on average, then the range of possible human lifespans is effectively infinite, and each one would have equal probability. Since the person in this example is celebrating her 50th birthday, this implies that this isn't the case; it would simply be too extraordinary that we'd randomly stumble into someone celebrating their 50th birthday when she could just as easily have been celebrating a birthday corresponding to a random number (a number chosen randomly out of all possible numbers would be infinitely likely to be infinitely large). Thus, we have to assume that human life span does not extend indefinitely, in which case Gotts rule's estimation has to be adjusted. This doesn't undermine Gott's rule completely, it just means that Gott's rule tends to overestimate at the extreme ends of the spectrum because it doesn't make any assumptions regarding limits on the possible range of values.
dylancatlow
Posts: 12,244
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1/10/2016 12:25:41 AM
Posted: 11 months ago
I should probably clarify that the estimate of 9,120 years has to do with the upper bound of the predicted lifespan of humanity. That is, there is a 95 percent chance, according to the argument, that humanity will be extinct within the next 9,120 years. The predicted lifespan is much less than that, no more than a few hundred years.
000ike
Posts: 11,196
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1/10/2016 12:54:30 AM
Posted: 11 months ago
At 1/9/2016 9:32:12 PM, dylancatlow wrote:
"The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far. Simply put, it says that supposing that all humans are born in a random order, chances are that any one human is born roughly in the middle... Assuming that the world population stabilizes at 10 billion and a life expectancy of 80 years, it can be estimated that the remaining 1,140 billion humans will be born in 9,120 years. Depending on the projection of world population in the forthcoming centuries, estimates may vary, but the main point of the argument is that it is unlikely that more than 1.2 trillion humans will ever live on Earth."

Unfortunately, if the argument is fundamentally correct, the estimate of 9,120 years is far too generous. For much of human history the chances that someone would ponder this question was close to zero. Thus, the "60 billion humans who have been born so far" is the wrong sample to look at, since there was no chance we would be asking this question during much of that period. The relevant sample consists of the people who ponder the question, which is pretty much confined to people born in the last few decades.

Possible counterarguments:

1. "The a posteriori observation that extinction level events are rare could be offered as evidence that the DA's predictions are implausible; typically, extinctions of a dominant species happens less often than once in a million years. Therefore, it is argued that human extinction is unlikely within the next ten millennia."

Humans are simply not comparable to other species in this regard. Other species don't have nuclear weapons or the ability to rapidly destroy the environment.

2. "Another objection to the Doomsday Argument is that the expected total human population is actually infinite."

This is probably the best counterargument. If the age of the universe is infinite, and if this entails "everything happening an infinite number of times" then the doomsday argument collapses.

3. "One objection is that the possibility of your existing at all depends on how many humans will ever exist (N). If this is a high number, then the possibility of your existing is higher than if only a few humans will ever exist. Since you do indeed exist, this is evidence that the number of humans that will ever exist is high."

This is a terrible counterargument. There are countless "potential people" who don't exist, but who never get to ponder any of this. The only examples of people we have are those people who exist. Thus, those who ponder the question i.e., us, are not "randomly selected" out of all the possible people, but rather out of the people who exist. In other words, it's not as if all potential people were laid out on a table, and when we closed our eyes and randomly pointed to one they happened to exist. That *would* imply that a significant portion of potential people end up existing. Rather, what we have amounts to an extreme form of selection bias.

4. "The Bayesian argument by Carlton M. Caves says that the uniform distribution assumption is incompatible with the Copernican principle, not a consequence of it.

He gives a number of examples to argue that Gott's rule is implausible. For instance, he says, imagine stumbling into a birthday party, about which you know nothing:

Your friendly enquiry about the age of the celebrant elicits the reply that she is celebrating her (tp = ) 50th birthday. According to Gott, you can predict with 95% confidence that the woman will survive between [50]/39 = 1.28 years and 39["50] = 1,950 years into the future. Since the wide range encompasses reasonable expectations regarding the woman's survival, it might not seem so bad, till one realizes that [Gott's rule] predicts that with probability 1/2 the woman will survive beyond 100 years old and with probability 1/3 beyond 150. Few of us would want to bet on the woman's survival using Gott's rule."

In the absence of any knowledge about biological lifespan, this would be a reasonable estimate. If we make no assumptions about how long humans live on average, then the range of possible human lifespans is effectively infinite, and each one would have equal probability. Since the person in this example is celebrating her 50th birthday, this implies that this isn't the case; it would simply be too extraordinary that we'd randomly stumble into someone celebrating their 50th birthday when she could just as easily have been celebrating a birthday corresponding to a random number (a number chosen randomly out of all possible numbers would be infinitely likely to be infinitely large). Thus, we have to assume that human life span does not extend indefinitely, in which case Gotts rule's estimation has to be adjusted. This doesn't undermine Gott's rule completely, it just means that Gott's rule tends to overestimate at the extreme ends of the spectrum because it doesn't make any assumptions regarding limits on the possible range of values.

http://reactiongif.org...
"A stupid despot may constrain his slaves with iron chains; but a true politician binds them even more strongly with the chain of their own ideas" - Michel Foucault
dylancatlow
Posts: 12,244
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1/10/2016 12:57:01 AM
Posted: 11 months ago
At 1/10/2016 12:54:30 AM, 000ike wrote:
At 1/9/2016 9:32:12 PM, dylancatlow wrote:
"The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far. Simply put, it says that supposing that all humans are born in a random order, chances are that any one human is born roughly in the middle... Assuming that the world population stabilizes at 10 billion and a life expectancy of 80 years, it can be estimated that the remaining 1,140 billion humans will be born in 9,120 years. Depending on the projection of world population in the forthcoming centuries, estimates may vary, but the main point of the argument is that it is unlikely that more than 1.2 trillion humans will ever live on Earth."

Unfortunately, if the argument is fundamentally correct, the estimate of 9,120 years is far too generous. For much of human history the chances that someone would ponder this question was close to zero. Thus, the "60 billion humans who have been born so far" is the wrong sample to look at, since there was no chance we would be asking this question during much of that period. The relevant sample consists of the people who ponder the question, which is pretty much confined to people born in the last few decades.

Possible counterarguments:

1. "The a posteriori observation that extinction level events are rare could be offered as evidence that the DA's predictions are implausible; typically, extinctions of a dominant species happens less often than once in a million years. Therefore, it is argued that human extinction is unlikely within the next ten millennia."

Humans are simply not comparable to other species in this regard. Other species don't have nuclear weapons or the ability to rapidly destroy the environment.

2. "Another objection to the Doomsday Argument is that the expected total human population is actually infinite."

This is probably the best counterargument. If the age of the universe is infinite, and if this entails "everything happening an infinite number of times" then the doomsday argument collapses.

3. "One objection is that the possibility of your existing at all depends on how many humans will ever exist (N). If this is a high number, then the possibility of your existing is higher than if only a few humans will ever exist. Since you do indeed exist, this is evidence that the number of humans that will ever exist is high."

This is a terrible counterargument. There are countless "potential people" who don't exist, but who never get to ponder any of this. The only examples of people we have are those people who exist. Thus, those who ponder the question i.e., us, are not "randomly selected" out of all the possible people, but rather out of the people who exist. In other words, it's not as if all potential people were laid out on a table, and when we closed our eyes and randomly pointed to one they happened to exist. That *would* imply that a significant portion of potential people end up existing. Rather, what we have amounts to an extreme form of selection bias.

4. "The Bayesian argument by Carlton M. Caves says that the uniform distribution assumption is incompatible with the Copernican principle, not a consequence of it.

He gives a number of examples to argue that Gott's rule is implausible. For instance, he says, imagine stumbling into a birthday party, about which you know nothing:

Your friendly enquiry about the age of the celebrant elicits the reply that she is celebrating her (tp = ) 50th birthday. According to Gott, you can predict with 95% confidence that the woman will survive between [50]/39 = 1.28 years and 39["50] = 1,950 years into the future. Since the wide range encompasses reasonable expectations regarding the woman's survival, it might not seem so bad, till one realizes that [Gott's rule] predicts that with probability 1/2 the woman will survive beyond 100 years old and with probability 1/3 beyond 150. Few of us would want to bet on the woman's survival using Gott's rule."

In the absence of any knowledge about biological lifespan, this would be a reasonable estimate. If we make no assumptions about how long humans live on average, then the range of possible human lifespans is effectively infinite, and each one would have equal probability. Since the person in this example is celebrating her 50th birthday, this implies that this isn't the case; it would simply be too extraordinary that we'd randomly stumble into someone celebrating their 50th birthday when she could just as easily have been celebrating a birthday corresponding to a random number (a number chosen randomly out of all possible numbers would be infinitely likely to be infinitely large). Thus, we have to assume that human life span does not extend indefinitely, in which case Gotts rule's estimation has to be adjusted. This doesn't undermine Gott's rule completely, it just means that Gott's rule tends to overestimate at the extreme ends of the spectrum because it doesn't make any assumptions regarding limits on the possible range of values.

http://reactiongif.org...

You're right. The end of humanity is like YAWN. Next topic please
ShabShoral
Posts: 3,229
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11/9/2016 3:09:04 AM
Posted: 3 weeks ago
At 11/9/2016 3:07:51 AM, dylancatlow wrote:
Argument confirmed

I think you misheard - Clinton is *losing*.
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dylancatlow
Posts: 12,244
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11/9/2016 3:19:45 AM
Posted: 3 weeks ago
At 11/9/2016 3:09:04 AM, ShabShoral wrote:
At 11/9/2016 3:07:51 AM, dylancatlow wrote:
Argument confirmed

I think you misheard - Clinton is *losing*.

That was good
ShabShoral
Posts: 3,229
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11/9/2016 3:25:46 AM
Posted: 3 weeks ago
At 11/9/2016 3:19:45 AM, dylancatlow wrote:
At 11/9/2016 3:09:04 AM, ShabShoral wrote:
At 11/9/2016 3:07:51 AM, dylancatlow wrote:
Argument confirmed

I think you misheard - Clinton is *losing*.

That was good

I'm glad you're falling in line.
"This site is trash as a debate site. It's club penguin for dysfunctional adults."

~ Skepsikyma <3

"Your idea of good writing is like Spinoza mixed with Heidegger."

~ Dylly Dylly Cat Cat

"You seem to aspire to be a cross between a Jewish hipster, an old school WASP aristocrat, and a political iconoclast"

~ Thett the Mighty

"fvck omg ur face"

~ Liz
dylancatlow
Posts: 12,244
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11/9/2016 3:33:07 AM
Posted: 3 weeks ago
At 11/9/2016 3:25:46 AM, ShabShoral wrote:
At 11/9/2016 3:19:45 AM, dylancatlow wrote:
At 11/9/2016 3:09:04 AM, ShabShoral wrote:
At 11/9/2016 3:07:51 AM, dylancatlow wrote:
Argument confirmed

I think you misheard - Clinton is *losing*.

That was good

I'm glad you're falling in line.

Heil trump
Philosophy101
Posts: 122
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11/15/2016 12:29:04 AM
Posted: 2 weeks ago
At 1/9/2016 9:32:12 PM, dylancatlow wrote:
"The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far. Simply put, it says that supposing that all humans are born in a random order, chances are that any one human is born roughly in the middle... Assuming that the world population stabilizes at 10 billion and a life expectancy of 80 years, it can be estimated that the remaining 1,140 billion humans will be born in 9,120 years. Depending on the projection of world population in the forthcoming centuries, estimates may vary, but the main point of the argument is that it is unlikely that more than 1.2 trillion humans will ever live on Earth."

Unfortunately, if the argument is fundamentally correct, the estimate of 9,120 years is far too generous. For much of human history the chances that someone would ponder this question was close to zero. Thus, the "60 billion humans who have been born so far" is the wrong sample to look at, since there was no chance we would be asking this question during much of that period. The relevant sample consists of the people who ponder the question, which is pretty much confined to people born in the last few decades.

Possible counterarguments:

1. "The a posteriori observation that extinction level events are rare could be offered as evidence that the DA's predictions are implausible; typically, extinctions of a dominant species happens less often than once in a million years. Therefore, it is argued that human extinction is unlikely within the next ten millennia."

Humans are simply not comparable to other species in this regard. Other species don't have nuclear weapons or the ability to rapidly destroy the environment.

2. "Another objection to the Doomsday Argument is that the expected total human population is actually infinite."

This is probably the best counterargument. If the age of the universe is infinite, and if this entails "everything happening an infinite number of times" then the doomsday argument collapses.

3. "One objection is that the possibility of your existing at all depends on how many humans will ever exist (N). If this is a high number, then the possibility of your existing is higher than if only a few humans will ever exist. Since you do indeed exist, this is evidence that the number of humans that will ever exist is high."

This is a terrible counterargument. There are countless "potential people" who don't exist, but who never get to ponder any of this. The only examples of people we have are those people who exist. Thus, those who ponder the question i.e., us, are not "randomly selected" out of all the possible people, but rather out of the people who exist. In other words, it's not as if all potential people were laid out on a table, and when we closed our eyes and randomly pointed to one they happened to exist. That *would* imply that a significant portion of potential people end up existing. Rather, what we have amounts to an extreme form of selection bias.

4. "The Bayesian argument by Carlton M. Caves says that the uniform distribution assumption is incompatible with the Copernican principle, not a consequence of it.

He gives a number of examples to argue that Gott's rule is implausible. For instance, he says, imagine stumbling into a birthday party, about which you know nothing:

Your friendly enquiry about the age of the celebrant elicits the reply that she is celebrating her (tp = ) 50th birthday. According to Gott, you can predict with 95% confidence that the woman will survive between [50]/39 = 1.28 years and 39["50] = 1,950 years into the future. Since the wide range encompasses reasonable expectations regarding the woman's survival, it might not seem so bad, till one realizes that [Gott's rule] predicts that with probability 1/2 the woman will survive beyond 100 years old and with probability 1/3 beyond 150. Few of us would want to bet on the woman's survival using Gott's rule."

In the absence of any knowledge about biological lifespan, this would be a reasonable estimate. If we make no assumptions about how long humans live on average, then the range of possible human lifespans is effectively infinite, and each one would have equal probability. Since the person in this example is celebrating her 50th birthday, this implies that this isn't the case; it would simply be too extraordinary that we'd randomly stumble into someone celebrating their 50th birthday when she could just as easily have been celebrating a birthday corresponding to a random number (a number chosen randomly out of all possible numbers would be infinitely likely to be infinitely large). Thus, we have to assume that human life span does not extend indefinitely, in which case Gotts rule's estimation has to be adjusted. This doesn't undermine Gott's rule completely, it just means that Gott's rule tends to overestimate at the extreme ends of the spectrum because it doesn't make any assumptions regarding limits on the possible range of values.

If the doomsday argument is correct, it would seem we are living somewhere in the middle of humanity's existence. If humanity has 60bil people then we can expect 60bil more people to resist or 480 more years of humanity. There appear to be several caveats to this including both nuclear war and interstellar travel. Furthermore we could be living at the beginning of humanity's longer reign or the end of a very short reign. I don't see what the doomsday argument proves except perhaps to give food for thought.