Even if it’s really a bad argument, the badness is far from obvious—just look at the Wikipedia page.
The fact that people are willing to believe something doesn’t make it not obviously wrong. It just means they are, for whatever reason, blind to it’s obvious wrongness.
For an example of why it fails in real-world terms consider the problem of coming up with the reference class. Humans? Great Apes? Apes? Mammals? Verterbrates? Earth-origin Living Organisms? Each produce a different prediction for the doomsday scenario, but a lot of plausible extinction paths for humans would at least take the rest of the apes with us.
For an example of why it fails the moment we have other evidence, consider Bob. Bob is 40 years old. He believes the doomsday argument. Someone points a gun at Bob, and threatens to kill him if he doesn’t give up his wallet. Bob reasons “There’s only a 0.001% chance that I’m in the last 0.001% of my life; so the danger of me dying in the next two hours is miniscule!”. Is Bob right?
Now suppose that Sean has just turned 21, 3 months ago. Just become an adult. He concludes, from the doomsday argument, that as he’s been an adult for 3 months, he has a 95% of stopping being an adult within 60 months, 5 years. So, he’s going to die within 5 years?
A snap judgment cannot lead you from Zeno’s paradox to discovering calculus.
No, but a snap judgement can lead you to correctly conclude that if each time you halve the distance you halve the time you’re going to have a finite amount of time to cross the line, even if you have an infinite amount of instants.
One nice formulation of the reference class for the DA is “observer-moments that think about the DA”. Maybe there are even better formulations.
About Bob: the question is whether the DA constitutes valid evidence, not whether it’s complete evidence. Of course the gun is stronger. But if you were in a state of near-total ignorance, would the DA not sway you even a little bit?
About Sean: most adults who consider Sean’s “adult doomsday” variation will turn out to be right. You have simply cherry-picked a counterexample. If such tactics were valid for breaking the DA, they would also break all probabilistic reasoning, which isn’t what we want.
It looks to me like you’re trying to fight your way to a preordained conclusion (“see! it was wrong all along!”), this is almost always a bad sign.
One nice formulation of the reference class for the DA is “observer-moments that think about the DA”. Maybe there are even better formulations.
And that might even concievably be a good formulation. That is NOT obviously a bad argument. It may or may not be a good argument, but it’s not obviously bad. I can’t just plug in a word-substitution and get the same argument to say something different without breaking the argument.
It’s also not the argument you presented me with. You presented me with the argument formulated over humans. Which is obviously a bad argument.
About Bob: the question is whether the DA constitutes valid evidence, not whether it’s complete evidence. Of course the gun is stronger. But if you were in a state of near-total ignorance, would the DA not sway you even a little bit?
No, because reference classes that are identical with regard to the present, ie. Humans and Cyborgs. Humans. Humans who live their entire life on Earth. Can be very different. And hypothetical ignorant me would be able to come up with such reference classes, unless hypothetical ignorant me lives in a very very simplified world.
In an extremely simplified world, with my only knowledge being that I am Mr. 989,954,292,132, I might buy into the doomsday argument as regards Mr.s
About Sean: most adults who consider Sean’s “adult doomsday” variation will turn out to be right. You have simply cherry-picked a counterexample. If such tactics were valid for breaking the DA, they would also break all probabilistic reasoning, which isn’t what we want.
True, my apologies, that was an obviously bad argument, and I missed it.
I’ve had prolonged debate with philosphers who honestly seem to believe that colour doesn’t really exist. With Truthers who think that the US government bombed the main two WTC towers; but have no concept as to why the US government would need to do so.
Really? I’m not a Truther but I could come up with a just so story at the drop of a hat.
There’s no need to bomb the towers, risking discovery, when simply having the smouldering towers standing there will be sufficient excuse.
The planes, on their own, accomplish the “give the politicians an excuse” goal. Bombing the towers as well can’t be explained by a goal that’s already achieved.
The fact that people are willing to believe something doesn’t make it not obviously wrong. It just means they are, for whatever reason, blind to it’s obvious wrongness.
For an example of why it fails in real-world terms consider the problem of coming up with the reference class. Humans? Great Apes? Apes? Mammals? Verterbrates? Earth-origin Living Organisms? Each produce a different prediction for the doomsday scenario, but a lot of plausible extinction paths for humans would at least take the rest of the apes with us.
For an example of why it fails the moment we have other evidence, consider Bob. Bob is 40 years old. He believes the doomsday argument. Someone points a gun at Bob, and threatens to kill him if he doesn’t give up his wallet. Bob reasons “There’s only a 0.001% chance that I’m in the last 0.001% of my life; so the danger of me dying in the next two hours is miniscule!”. Is Bob right?
Now suppose that Sean has just turned 21, 3 months ago. Just become an adult. He concludes, from the doomsday argument, that as he’s been an adult for 3 months, he has a 95% of stopping being an adult within 60 months, 5 years. So, he’s going to die within 5 years?
No, but a snap judgement can lead you to correctly conclude that if each time you halve the distance you halve the time you’re going to have a finite amount of time to cross the line, even if you have an infinite amount of instants.
One nice formulation of the reference class for the DA is “observer-moments that think about the DA”. Maybe there are even better formulations.
About Bob: the question is whether the DA constitutes valid evidence, not whether it’s complete evidence. Of course the gun is stronger. But if you were in a state of near-total ignorance, would the DA not sway you even a little bit?
About Sean: most adults who consider Sean’s “adult doomsday” variation will turn out to be right. You have simply cherry-picked a counterexample. If such tactics were valid for breaking the DA, they would also break all probabilistic reasoning, which isn’t what we want.
It looks to me like you’re trying to fight your way to a preordained conclusion (“see! it was wrong all along!”), this is almost always a bad sign.
And that might even concievably be a good formulation. That is NOT obviously a bad argument. It may or may not be a good argument, but it’s not obviously bad. I can’t just plug in a word-substitution and get the same argument to say something different without breaking the argument.
It’s also not the argument you presented me with. You presented me with the argument formulated over humans. Which is obviously a bad argument.
No, because reference classes that are identical with regard to the present, ie. Humans and Cyborgs. Humans. Humans who live their entire life on Earth. Can be very different. And hypothetical ignorant me would be able to come up with such reference classes, unless hypothetical ignorant me lives in a very very simplified world.
In an extremely simplified world, with my only knowledge being that I am Mr. 989,954,292,132, I might buy into the doomsday argument as regards Mr.s
True, my apologies, that was an obviously bad argument, and I missed it.
[comment deleted]
Really? I’m not a Truther but I could come up with a just so story at the drop of a hat.
As could I. However the average truther has been convinced that it was done as an excuse to go to war.
But I deleted that part of the post for a reason. Politics is the mindkiller and all.
… Lost me. That sounds like a concept as to why to me. (Which is not to say that it is a likely possibility.)
There’s no need to bomb the towers, risking discovery, when simply having the smouldering towers standing there will be sufficient excuse.
The planes, on their own, accomplish the “give the politicians an excuse” goal. Bombing the towers as well can’t be explained by a goal that’s already achieved.