The sky tends to be blue in worlds that have had less catastrophic events
C: Catastrophic events are less likely
Is identical in form to,
The historical record lacks catastrophic events
The historical record will tend to lack catastrophic events in worlds that have less catastrophic events
C: Catastrophic events are less likely
However, there is the other argument
The historical record lacks catastrophic events
The historical record will tend to lack catastrophic events in worlds that have less catastrophic events
C: This world will have had fewer catastrophic events than average
These can’t perfectly cancel out or we could never know anything, the net result of these two arguments must still be a decrease in how likely we take catastrophic risks. I do think it’s because we can’t discover we don’t exist that is the relevant distinction.
If I can only exist in a world with a blue sky then the fact that the sky is blue should not make me think it is more likely for worlds to have a blue sky. This is why the argument, that life is likely to exist throughout the universe because it happened here doesn’t work. If I can only exist in a world with life then the fact that life exists in this world shouldn’t influence how likely I think it is to be in another world, other than me knowing it is possible.
I responded to your comment on the other post I am happy to continue chatting in DMs if you like.
I am very confident that the arguments do perfectly cancel out in the sky-colour case. There is nothing philosophically confusing about the sky-colour case, it’s just an application of conditional probability.
That doesn’t mean we can never learn anything. It just means that if X and Y are independent after controlling for a third variable Z, then learning X can give you no additional information about Y if you already know Z. That’s true in general. Here X is the colour of the sky, Y is the probability of a catastrophic event occurring, and Z is the number of times the catastrophic event has occurred in the past.
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In the Russian roulette example, you can only exist if the gun doesn’t fire, but you can still use your existence to conclude that it is more likely that the gun won’t fire (i.e. that you picked up the safer gun). The same should be true in anthropic shadow, at least in the one world case.
Fine tuning is helpful to think about here too. Fine tuning can be explained anthropically, but only if a large number of worlds actually exist. If there was only one solar system, with only one planet, then the fine tuning of conditions on that planet for life would be surprising. Saying that we couldn’t have existed otherwise does not explain it away (at least in my opinion, for reasons I tried to justify in the ‘possible solution #1’ section).
In analogy with the anthropic explanation of fine-tuning, anthropic shadow might come back if there are many observer-containing worlds. You learn less from your existence in that case, so there’s not necessarily a neat cancellation of the two arguments. But I explored that potential justification for anthropic shadow in the second section, and couldn’t make that work either.
These arguments don’t cancel out. The argument
The sky is blue
The sky tends to be blue in worlds that have had less catastrophic events
C: Catastrophic events are less likely
Is identical in form to,
The historical record lacks catastrophic events
The historical record will tend to lack catastrophic events in worlds that have less catastrophic events
C: Catastrophic events are less likely
However, there is the other argument
The historical record lacks catastrophic events
The historical record will tend to lack catastrophic events in worlds that have less catastrophic events
C: This world will have had fewer catastrophic events than average
These can’t perfectly cancel out or we could never know anything, the net result of these two arguments must still be a decrease in how likely we take catastrophic risks. I do think it’s because we can’t discover we don’t exist that is the relevant distinction.
If I can only exist in a world with a blue sky then the fact that the sky is blue should not make me think it is more likely for worlds to have a blue sky. This is why the argument, that life is likely to exist throughout the universe because it happened here doesn’t work. If I can only exist in a world with life then the fact that life exists in this world shouldn’t influence how likely I think it is to be in another world, other than me knowing it is possible.
I responded to your comment on the other post I am happy to continue chatting in DMs if you like.
I am very confident that the arguments do perfectly cancel out in the sky-colour case. There is nothing philosophically confusing about the sky-colour case, it’s just an application of conditional probability.
That doesn’t mean we can never learn anything. It just means that if X and Y are independent after controlling for a third variable Z, then learning X can give you no additional information about Y if you already know Z. That’s true in general. Here X is the colour of the sky, Y is the probability of a catastrophic event occurring, and Z is the number of times the catastrophic event has occurred in the past.
---
In the Russian roulette example, you can only exist if the gun doesn’t fire, but you can still use your existence to conclude that it is more likely that the gun won’t fire (i.e. that you picked up the safer gun). The same should be true in anthropic shadow, at least in the one world case.
Fine tuning is helpful to think about here too. Fine tuning can be explained anthropically, but only if a large number of worlds actually exist. If there was only one solar system, with only one planet, then the fine tuning of conditions on that planet for life would be surprising. Saying that we couldn’t have existed otherwise does not explain it away (at least in my opinion, for reasons I tried to justify in the ‘possible solution #1’ section).
In analogy with the anthropic explanation of fine-tuning, anthropic shadow might come back if there are many observer-containing worlds. You learn less from your existence in that case, so there’s not necessarily a neat cancellation of the two arguments. But I explored that potential justification for anthropic shadow in the second section, and couldn’t make that work either.