[ExI] Fwd: [tt] The Habitable Epoch of the Early Universe

[Eugen Leitl]

On Thu, Dec 12, 2013 at 02:13:36PM +0000, Anders Sandberg wrote:

> Exactly. And now the diadem needs to think about what probability it
> should assign to the existence of other diadems. The diadem using

If the diadem is honest, it cannot assign any probabilities.

> the SSA should think there are a lot of diadems, while the

The SSA diadem has no basis for that assumption. (It happens
to be the only one, I'm God, and I put it there because
I'm evil that way).

> SIA-believer diadem should favour theories where there are loads of
> observers (but not necessarily diadems). However, the unique diadem

The SIA diadem has no basis for that assumption either. 

> observer is also an "anomalous observer" - most observers are by
> definition common, and they would get things more right when

This is circular logic. You have no idea how common your class is,
until you have an unbiased sample. You do not have an unbiased sample,
hence you have no idea how common you are. Other than there is at least 
one instance of your class, at which point stochastics and probability 
goes down the toilet. No observer-moments for you.

> reasoning with the SSA.
> 
> Reasoning from no data or a single, biased data point will of course
> on average produce much worse fits to reality than reasoning from

But you cannot fit for reality, because you do not know what 
reality is. Circular logic, again. Everything changes with
the second sample. It only changes very little with the third
sample. 

> more data. But that doesn't mean it is irrelevant - if you have no
> data. It is better to make the argument clear and the assumptions
> overt.

I'd wish the arbitrary assumptions would be made very clear.
 
> Same thing with Bayesian probability: yes, it involves subjective
> judgements (constrained by logic, data and  probability theory), but
> it allows you to think about somewhat important things like
> Pr(humanity going extinct|current actions) that frequentism cannot
> handle at all.

I can think about ten impossible things before breakfast.
Just because I can does not make them any more real.